Marek Mirski - Academia.edu (original) (raw)
Papers by Marek Mirski
EEG and field potential rhythms established in the cortex and thalamus may accommodate the propag... more EEG and field potential rhythms established in the cortex and thalamus may accommodate the propagation of seizures. This article describes the interaction between thalamus and cortex during pentylenetetrazol (PTZ) seizures in rats with and without prior treatment with ethosuximide (ESM), a well-known antiepileptic drug (AED) that raises the threshold for seizures, was given before PTZ. The AED was given before PTZ convulsant administration. We track this thalamo-cortical association with a novel measure we have called the cross-bicoherence gain, or BISCOH. This quantity allows us to measure the spectral coherence in a purely higher order spectralmethodology. BISCOH is able to track the formation of nonlinearities at specific frequencies in the recorded EEG. BISCOH showed a strong increase in low alpha wave harmonic generationat 10 and 12.5 Hz after ESM treatment (p < 0.02 and p < 0.007, respectively). Conventional coherence failed to show distinctive and significant changes in thalamo-cortical coupling after ESM treatment at those frequencies and instead showed changes at 5 Hz. This rise in cortical rhythms is evidence of harmonic generation or new frequency formation in the thalamo-cortical system withAED therapy. BISCOH could become a powerful tool in unraveling changes in coherence due to neuroelectric modulation resulting from drug treatment or electrical stimulation.
Seminars in Spine Surgery, 2011
Journal of medical speech-language pathology, 2014
To describe the types of talking tracheostomy tubes available, present four case studies of criti... more To describe the types of talking tracheostomy tubes available, present four case studies of critically ill patients who used a specialized tracheostomy tube to improve speech, discuss their advantages and disadvantages, propose patient selection criteria, and provide practical recommendations for medical care providers. Retrospective chart review of patients who underwent tracheostomy in 2010. Of the 220 patients who received a tracheostomy in 2010, 164 (74.55%) received a percutaneous tracheostomy and 56 (25.45%) received an open tracheostomy. Among the percutaneous tracheostomy patients, speech-language pathologists were consulted on 113 patients, 74 of whom were on a ventilator. Four of these 74 patients received a talking tracheostomy tube, and all four were able to speak successfully while on the mechanical ventilator even though they were unable to tolerate cuff deflation. Talking tracheostomy tubes allow patients who are unable to tolerate-cuff deflation to achieve phonation....
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
The early detection of epileptic seizures requires computing relevant statistics from multivariat... more The early detection of epileptic seizures requires computing relevant statistics from multivariate data and defining a robust decision strategy as a function of these statistics that accurately detects the transition from the normal to the peri-ictal (problematic) state. We model the afflicted brain as a hidden Markov model (HMM) with two hidden clinical states (normal and peri-ictal). The output of the HMM is a statistic computed from multivariate neural measurements. A Bayesian framework is developed to analyze the a posteriori conditional probability of being in peri-ictal state given current and past output measurements. We apply this method to multichannel intracortical EEGs (iEEGs) from the thalamo-cortical ictal pathway in an epilepsy rat model. We first define the output statistic as the max singular value of a connectivity matrix computed on the EEG channels with spectral techniques Then, we estimate the HMM transition probabilities from this statistic and track the a poste...
The Laryngoscope, 2007
Introduction: Percutaneous dilation tracheotomy (PDT) is now an accepted alternative to surgical ... more Introduction: Percutaneous dilation tracheotomy (PDT) is now an accepted alternative to surgical tracheotomy in certain patients. We began performing these procedures in 2000 and use it regularly in select intensive care unit patients requiring prolonged intubation and mechanical ventilation. Materials and Methods: A retrospective chart review of consecutive PDTs performed in the Department of Otolaryngology-Head and Neck Surgery at the John Hopkins Hospital between 2002 and 2005 was undertaken. Procedural and postoperative complications in an earlier group were compared with those in the later group for both frequency and severity. Results: Three hundred eighteen PDTs were performed on intensive care patients during this time period. All were performed using the Ciaglia method and the Cook Blue Rhino (Cook Medical Products, Bloomington, IN) set under direct bronchoscopic visualization. In group A (first 159 patients), there were a total of 12 complications (7.5%), including six cases of perioperative hemorrhage, whereas in group B (second 159 PDTs), there were seven complications (4.4%) with no cases of perioperative hemorrhage. Conclusions: PDT provides an easy and convenient alternative to open tracheotomy (OT) and should be added to the otolaryngologist's armamentarium of surgical airway procedures. The complication rate of PDT is low and similar to that of open operative tracheotomy. However, with experience and the use of strict protocols in both patient selection and PDT procedure, the complication rate can be significantly reduced further both in frequency and severity, making it even safer than an open operative tracheotomy.
Respiration, 2012
40.2%) were performed by the ST and 64 procedures (59.8%) were performed by IP. There was no stat... more 40.2%) were performed by the ST and 64 procedures (59.8%) were performed by IP. There was no statistical difference between the incidence of airway injury and infection between the two procedural groups. There were no deaths related to the performance of PDT in our series. PDT was completed within 48 h of request in 100% of IP patients and 95% of ST patients (p = 0.08). Conclusions: There were no statistical differences in PDT between the ST and IP groups when comparing complications. There was a trend towards an increased efficiency in time to PDT after consultation within the IP PDT group. Trained IP can safely and effectively perform PDT.
Otolaryngology - Head and Neck Surgery, 2007
Conclusion: Several lessons have been learned. Apparently minor superficial-appearing wounds are ... more Conclusion: Several lessons have been learned. Apparently minor superficial-appearing wounds are frequently associated with devastating deep head and neck pathology. Also, our high rate of intraoperative pathology discovered with high velocity penetrating neck trauma mandates surgical exploration for all symptomatic and asymptomatic neck wounds with the rare exception of asymptomatic zone three injuries. Finally, limited resources during the treatment of a mass casualty often means that surgery needs to be reserved for those patients with a reasonable expectation of survival.
Neurology, 2009
Objective: To evaluate the role of 23.4% saline in the management of transtentorial herniation (T... more Objective: To evaluate the role of 23.4% saline in the management of transtentorial herniation (TTH) in patients with supratentorial lesions.
Neurocritical Care, 2012
Neurocritical care is a new subspecialty field in medicine that intersects with many of the neuro... more Neurocritical care is a new subspecialty field in medicine that intersects with many of the neuroscience and critical care specialties, and continues to evolve in its scope of practice and practitioners. The objective of this study was to assess the perceived need for and roles of neurocritical care intensivists and neurointensive care units among physicians involved with intensive care and the neurosciences. An online survey of physicians practicing critical care medicine, and neurology was performed during the 2008 Leapfrog initiative to formally recognize neurocritical care training. The survey closed in July 2009 and achieved a 13% response rate (980/7524 physicians surveyed). Survey respondents (mostly from North America) included 362 (41.4%) neurologists, 164 (18.8%) internists, 104 (11.9%) pediatric intensivists, 82 (9.4%) anesthesiologists, and 162 (18.5%) from other specialties. Over 70% of respondents reported that the availability of neurocritical care units staffed with neurointensivists would improve the quality of care of critically ill neurological/neurosurgical patients. Neurologists were reported as the most appropriate specialty for training in neurointensive care by 53.3%, and 57% of respondents responded positively that neurology residency programs should offer a separate training track for those interested in neurocritical care. Broad level of support exists among the survey respondents (mostly neurologists and intensivists) for the establishment of neurological critical care units. Since neurology remains the predominant career path from which to draw neurointensivists, there may be a role for more comprehensive neurointensive care training within neurology residencies or an alternative training track for interested residents.
Neurocritical Care, 2008
To investigate the impact of statins on perihematomal edema following spontaneous supratentorial ... more To investigate the impact of statins on perihematomal edema following spontaneous supratentorial intracerebral hemorrhage (ICH). Hematoma expansion and evolution of perihematomal edema are most commonly responsible for neurological deterioration following ICH. A possible role of statins in reducing perihematomal edema has been suggested based on studies in animal models. Records of consecutive ICH patients admitted to The Johns Hopkins Hospital from 1999 to 2006 were reviewed. Patients with ICH related to trauma or underlying lesions (e.g., brain tumors, aneurysms, and arterio-venous malformations) and of infratentorial location were excluded. Absolute and relative perihematomal edema were assessed on initial head CT. Using regression analysis, the impact of prior statin use on absolute and relative edema at presentation was assessed correcting for other factors possibly impacting perihematomal edema, such as age, coagulopathy, aspirin use, admission mean arterial pressure (MAP), and blood glucose. A total of 125 consecutive ICH patients were studied. Patients with prior statin exposure had a mean edema volume of 13.2 +/- 9.2 cc compared to 22.3 +/- 18.3 cc in patients who were not using statins at the time of ICH. Following multiple linear regression analysis, we have identified a statistically significant association between prior statin use with reduced early absolute perihematomal edema (P = 0.035). Mean relative perihematomal edema was significantly lower in patients on statins at presentation (0.44) as opposed to 0.81 in patients with no prior statin use. This difference remained statistically significant (P = 0.021) after correcting for other variables. We report the association between statin use prior to ICH and decreased absolute and relative perihematomal edema. A prospective study analyzing the role of statins in perihematomal edema reduction and the resultant effect on mortality and functional outcomes following ICH is warranted.
Neurocritical Care, 2008
To assess the impact of blood glucose, coagulopathy, seizures and prior statin and aspirin use on... more To assess the impact of blood glucose, coagulopathy, seizures and prior statin and aspirin use on clinical outcome following intracerebral hemorrhage (ICH). Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes with mortality rates approaching 50%. Glasgow Coma Scale (GCS), ICH volume, age, pulse pressure, ICH location, intraventricular hemorrhage (IVH) and hydrocephalus are known to impact 30-day survival following ICH and are included in various prediction models. The role of other clinical variables in the long-term outcome of these patients is less clear. Records of consecutive ICH patients admitted to The Johns Hopkins Hospital from 1999 to 2006 were reviewed. Patients with ICH related to trauma or underlying lesions (e.g. brain tumors, aneurysms, arterio-venous malformations) and of infratentorial location were excluded. The impact of admission blood glucose, coagulopathy, seizures on presentation and prior statin and aspirin use on 30-day mortality and functional outcomes at discharge was assessed using dichotomized Modified Rankin Scale (dMRS) and Glasgow Outcomes scale (dGOS). Other variables known to impact outcomes that were included in the multiple logistic regression analysis were age, admission GCS, pulse pressure, ICH volume, ICH location, volume of IVH and hydrocephalus. A total of 314 patients with ICH were identified, 125 met inclusion criteria. Patients&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; age ranged from 34 to 90 years (mean 63.5), 57.6 % were male. Mean ICH volume was 32.09 cc (range 1-214 cc). Following multiple logistic regression analysis, prior statin use (P = 0.05) was found to be associated with decreased mortality with a greater than 12-fold odds of survival while admission blood glucose (P = 0.023) was associated with increased 30-day mortality. Coagulopathy, seizures on presentation, and prior aspirin use had no significant impact on 30-day mortality or outcomes at discharge in our study cohort. The significant association of prior statin use with decreased mortality warrants prospective evaluation of the use of statins following ICH.
Journal of Neurosurgical Anesthesiology, 2003
Traumatic spinal cord injury is frequently associated with brain injury and with alterations in r... more Traumatic spinal cord injury is frequently associated with brain injury and with alterations in respiratory and cardiovascular function that require critical care management. Complications include respiratory failure, atelectasis, pneumonia, neurogenic shock, autonomic dysreflexia, venous thromboembolism, and sepsis. While complications may be managed with supportive care, the goal of ameliorating neurologic outcome has proved elusive. Methylprednisolone, when instituted <8 hours after traumatic spinal cord injury, was associated in two clinical trials with statistically significant improvements in motor scores at 6 months and 1 year; however, critical reappraisal of these data raises questions about their validity and clinical relevance. Until more evidence of clinically effective therapies is available, acute management must be driven by pathophysiologic principles, with emphasis on interventions that attenuate secondary neurologic injury; these include the rational use of immobilization, cautious airway management, and promotion of cord perfusion and oxygenation with the appropriate level of hemodynamic and respiratory support. Clinical trials of pharmacologic neuroprotection have yielded disappointing results, but the ongoing elucidation of spinal cord repair and regenerative mechanisms suggests new therapeutic prospects.
Journal of Neurosurgical Anesthesiology, 2001
Analysis of patient data from a new neuroscience intensive care unit (NSICU) permitted evaluation... more Analysis of patient data from a new neuroscience intensive care unit (NSICU) permitted evaluation of whether such a specialty ICU favorably altered clinical outcomes in critically ill neuroscience patients, and whether such a care model produced an efficient use of resources. A retrospective review was performed to compare (1) the clinical outcomes, as defined by percent mortality and disposition at discharge, between patients with a primary diagnosis of intracerebral hemorrhage treated in 1995 in medical or surgical ICUs and those treated in the same medical facility in an NSICU in 1997; and (2) the efficiency of care, as defined by length of ICU stay, total cost of care, and specific resource use, between patients treated in the NSICU and national benchmark standards for general ICUs during the 1997 fiscal year (FY). In the latter, extracted patient population data on neurosurgery patients requiring ICU treatment during FY 1997 were used with the following adjacent-disease related group (A-DRG)-coded diseases: craniotomy with and without coma or intracerebral hemorrhage, and skull fracture with and without coma lasting longer than 1 hour. Outcome measures of percent mortality and disposition at discharge in patients with intracerebral hemorrhage were significantly improved (P < .05), compared with those in a similar cohort treated 2 years earlier in a general ICU setting. Also, patients treated in the NSICU had shorter hospital stays (P < .01 ) and lower total costs of care (P < .01) than a national benchmark. The data suggest that a neuroscience specialty ICU arena staffed by specialty-trained intensivists and nurses is beneficial.
Journal of Neurosurgery, 2007
Opioid administration after major intracranial surgery is often limited by a presumed lack of nee... more Opioid administration after major intracranial surgery is often limited by a presumed lack of need and a concern that opioids will adversely affect the postoperative neurological examination. The authors conducted a prospective study to evaluate the incidence, severity, and treatment of postoperative pain in patients who underwent major intracranial surgery. One hundred eighty-seven patients (77 men and 110 women, mean age 52 +/- 15 years, mean weight 78.1 +/- 19.9 kg) underwent either supratentorial (129 patients) or infratentorial (58 patients) procedures. Sixty-nine percent of the patients reported experiencing moderate to severe pain (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; or =4 on a 0-10 scale) during the 1st postoperative day. Pain scores greater than or equal to 4 persisted in 48% on the 2nd postoperative day. Approximately 80% of patients were treated with acetaminophen on the 1st postoperative day, whereas opioids (primarily intravenous fentanyl) were administered to 58%. Compared with patients who underwent supratentorial procedures, those who underwent infratentorial procedures reported more severe pain at rest (mean score 4.9 +/- 2.2 compared with 3.8 +/- 2.6; p = 0.015) and with movement (mean score 6.3 +/- 2.6 compared with 4.5 +/- 2.7; p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) on the 1st postoperative day. On both the 1st and 2nd postoperative days, patients who underwent infratentorial procedures received greater quantities of opioid (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 0.019) and nonopioid (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 0.013) analgesics than those who underwent supratentorial procedures. Patients&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; dissatisfaction with analgesic therapy was significantly associated with elevated pain levels on the first 2 postoperative days (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). In contrast to prevailing assumptions, the study findings reveal that most patients undergoing elective major intracranial surgery will experience moderate to severe pain for the first 2 days after surgery and that this pain is often inadequately treated.
Journal of Clinical Anesthesia, 2006
To evaluate the effect of 0.25% bupivacaine scalp block on alterations in hemodynamics and plasma... more To evaluate the effect of 0.25% bupivacaine scalp block on alterations in hemodynamics and plasma catecholamine metabolites during general anesthesia in patients undergoing frontotemporal craniotomy. Prospective, clinical study. Operating room of a university hospital. 16 ASA physical status II and III patients who were scheduled for frontotemporal craniotomy. Patients were prospectively randomized to receive a saline control (C group) or bupivacaine scalp block (SB group) as an adjuvant to general anesthesia using isoflurane in 50% N(2)O-O(2). Routine monitoring of electrocardiogram, heart rate (HR), and mean arterial blood pressure (MAP) were recorded at two-minute intervals from the beginning of anesthesia until 10 minutes after incision, followed by 5-minute intervals throughout the remaining course of the surgery. By prospective design, increases in MAP or HR by 20% above the mean baseline values were treated with 2.5 mg/kg of thiopental combined with 2 mug/kg of fentanyl. Arterial blood was sampled at 5 minutes before and after skin incision and at the start of dural opening for measuring serum catecholamine metabolites by high-performance liquid chromatography. Only two patients in the SB group needed additional anesthetics for stabilizing their hemodynamics during the course of anesthesia. In contrast, all C group patients required supplemental anesthesia for controlling the abrupt rise in hemodynamic parameters. In addition, absolute MAP and HR values were significantly higher in the C group than in the SB group during the surgical period between incision and dural opening. The differences in hemodynamics observed between the two groups were, however, not accompanied with a significant change in plasma catecholamine metabolites at each predetermined time interval measured. Pretreatment with 0.25% bupivacaine scalp block appeared to be an effective adjuvant treatment for maintaining stable hemodynamics for patients undergoing craniotomy during general anesthesia especially at the time of skin incision and dural opening. This study design was unable to discern any correlation between elevation in hemodynamic parameters and a rise in serum catecholamine levels.
Intensive Care Medicine, 2010
DEX may be a consequence of the intellect-sparing yet calming effect of this drug.
Intensive Care Medicine, 2009
IEEE Transactions on Biomedical Engineering, 2003
Our proposed algorithm for seizure prediction is based on the principle that seizure build-up is ... more Our proposed algorithm for seizure prediction is based on the principle that seizure build-up is always preceded by constantly changing bursting levels. We use a novel measure of residual subband wavelet entropy (RSWE) to directly estimate the entropy of bursts, which is otherwise obscured by the ongoing background activity. Our results are obtained using a slow infusion anesthetized pentylenetetrazol (PTZ) rat model in which we record field potentials (FPs) from frontal cortex and two thalamic areas (anterior and posterior nuclei). In each frequency band, except for the theta-delta frequency bands, we observed a significant build-up of RSWE from the preictal period to the first ictal event (p 0.05) in cortex. Significant differences were observed between cortical and thalamic RSWE (p 0.05) subsequent to seizure development. A key observation is the twofold increase in mean cortical RSWE from the preictal to interictal period. Exploiting this increase, we develop a slope change detector to discern early acceleration of entropy and predict the approaching seizure. We use multiple observations through sequential detection of slope changes to enhance the sensitivity of our prediction. Using the proposed method applied to a cohort of four rats subjected to PTZ infusion, we were able to predict the first seizure episode 28 min prior to its occurrence.
Epilepsy Research, 1997
Evidence suggests that a specific subcortical pathway synaptically linking the anterior thalamic ... more Evidence suggests that a specific subcortical pathway synaptically linking the anterior thalamic nuclear complex (AN) to the hypothalamus and midbrain is important in the expression of pentylenetetrazol (PTZ) seizures. Perturbation of neuronal activity along this path via focal disruption or chemical inhibition significantly raises seizure threshold. Recent data has demonstrated that focal electrical stimulation within the hypothalamic component of this pathway inhibited seizure expression in a current and frequency dependent fashion. Similar experiments were conducted in the AN to investigate the hypothesis that stimulation of this thalamic nuclear region can prevent the propagation of PTZ seizures between cortical and subcortical regions. Our results indicate that high frequency (100 Hz) stimulation of AN did not alter the expression of low dose PTZ induced cortical bursting but did raise the clonic seizure threshold compared to naive animals or those stimulated at sites near, but not in AN (P < 0.01). Low frequency stimulation (8 Hz) was in contrast, proconvulsant and could induce behavioral arrest responses accompanied by rhythmic high voltage EEG even without PTZ challenge. This data further highlights the role of AN in mediating the expression of seizures and provides experimental support for the concept that this thalamic region may be a promising target for focal stimulation to treat intractable seizures in humans.
EEG and field potential rhythms established in the cortex and thalamus may accommodate the propag... more EEG and field potential rhythms established in the cortex and thalamus may accommodate the propagation of seizures. This article describes the interaction between thalamus and cortex during pentylenetetrazol (PTZ) seizures in rats with and without prior treatment with ethosuximide (ESM), a well-known antiepileptic drug (AED) that raises the threshold for seizures, was given before PTZ. The AED was given before PTZ convulsant administration. We track this thalamo-cortical association with a novel measure we have called the cross-bicoherence gain, or BISCOH. This quantity allows us to measure the spectral coherence in a purely higher order spectralmethodology. BISCOH is able to track the formation of nonlinearities at specific frequencies in the recorded EEG. BISCOH showed a strong increase in low alpha wave harmonic generationat 10 and 12.5 Hz after ESM treatment (p < 0.02 and p < 0.007, respectively). Conventional coherence failed to show distinctive and significant changes in thalamo-cortical coupling after ESM treatment at those frequencies and instead showed changes at 5 Hz. This rise in cortical rhythms is evidence of harmonic generation or new frequency formation in the thalamo-cortical system withAED therapy. BISCOH could become a powerful tool in unraveling changes in coherence due to neuroelectric modulation resulting from drug treatment or electrical stimulation.
Seminars in Spine Surgery, 2011
Journal of medical speech-language pathology, 2014
To describe the types of talking tracheostomy tubes available, present four case studies of criti... more To describe the types of talking tracheostomy tubes available, present four case studies of critically ill patients who used a specialized tracheostomy tube to improve speech, discuss their advantages and disadvantages, propose patient selection criteria, and provide practical recommendations for medical care providers. Retrospective chart review of patients who underwent tracheostomy in 2010. Of the 220 patients who received a tracheostomy in 2010, 164 (74.55%) received a percutaneous tracheostomy and 56 (25.45%) received an open tracheostomy. Among the percutaneous tracheostomy patients, speech-language pathologists were consulted on 113 patients, 74 of whom were on a ventilator. Four of these 74 patients received a talking tracheostomy tube, and all four were able to speak successfully while on the mechanical ventilator even though they were unable to tolerate cuff deflation. Talking tracheostomy tubes allow patients who are unable to tolerate-cuff deflation to achieve phonation....
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
The early detection of epileptic seizures requires computing relevant statistics from multivariat... more The early detection of epileptic seizures requires computing relevant statistics from multivariate data and defining a robust decision strategy as a function of these statistics that accurately detects the transition from the normal to the peri-ictal (problematic) state. We model the afflicted brain as a hidden Markov model (HMM) with two hidden clinical states (normal and peri-ictal). The output of the HMM is a statistic computed from multivariate neural measurements. A Bayesian framework is developed to analyze the a posteriori conditional probability of being in peri-ictal state given current and past output measurements. We apply this method to multichannel intracortical EEGs (iEEGs) from the thalamo-cortical ictal pathway in an epilepsy rat model. We first define the output statistic as the max singular value of a connectivity matrix computed on the EEG channels with spectral techniques Then, we estimate the HMM transition probabilities from this statistic and track the a poste...
The Laryngoscope, 2007
Introduction: Percutaneous dilation tracheotomy (PDT) is now an accepted alternative to surgical ... more Introduction: Percutaneous dilation tracheotomy (PDT) is now an accepted alternative to surgical tracheotomy in certain patients. We began performing these procedures in 2000 and use it regularly in select intensive care unit patients requiring prolonged intubation and mechanical ventilation. Materials and Methods: A retrospective chart review of consecutive PDTs performed in the Department of Otolaryngology-Head and Neck Surgery at the John Hopkins Hospital between 2002 and 2005 was undertaken. Procedural and postoperative complications in an earlier group were compared with those in the later group for both frequency and severity. Results: Three hundred eighteen PDTs were performed on intensive care patients during this time period. All were performed using the Ciaglia method and the Cook Blue Rhino (Cook Medical Products, Bloomington, IN) set under direct bronchoscopic visualization. In group A (first 159 patients), there were a total of 12 complications (7.5%), including six cases of perioperative hemorrhage, whereas in group B (second 159 PDTs), there were seven complications (4.4%) with no cases of perioperative hemorrhage. Conclusions: PDT provides an easy and convenient alternative to open tracheotomy (OT) and should be added to the otolaryngologist's armamentarium of surgical airway procedures. The complication rate of PDT is low and similar to that of open operative tracheotomy. However, with experience and the use of strict protocols in both patient selection and PDT procedure, the complication rate can be significantly reduced further both in frequency and severity, making it even safer than an open operative tracheotomy.
Respiration, 2012
40.2%) were performed by the ST and 64 procedures (59.8%) were performed by IP. There was no stat... more 40.2%) were performed by the ST and 64 procedures (59.8%) were performed by IP. There was no statistical difference between the incidence of airway injury and infection between the two procedural groups. There were no deaths related to the performance of PDT in our series. PDT was completed within 48 h of request in 100% of IP patients and 95% of ST patients (p = 0.08). Conclusions: There were no statistical differences in PDT between the ST and IP groups when comparing complications. There was a trend towards an increased efficiency in time to PDT after consultation within the IP PDT group. Trained IP can safely and effectively perform PDT.
Otolaryngology - Head and Neck Surgery, 2007
Conclusion: Several lessons have been learned. Apparently minor superficial-appearing wounds are ... more Conclusion: Several lessons have been learned. Apparently minor superficial-appearing wounds are frequently associated with devastating deep head and neck pathology. Also, our high rate of intraoperative pathology discovered with high velocity penetrating neck trauma mandates surgical exploration for all symptomatic and asymptomatic neck wounds with the rare exception of asymptomatic zone three injuries. Finally, limited resources during the treatment of a mass casualty often means that surgery needs to be reserved for those patients with a reasonable expectation of survival.
Neurology, 2009
Objective: To evaluate the role of 23.4% saline in the management of transtentorial herniation (T... more Objective: To evaluate the role of 23.4% saline in the management of transtentorial herniation (TTH) in patients with supratentorial lesions.
Neurocritical Care, 2012
Neurocritical care is a new subspecialty field in medicine that intersects with many of the neuro... more Neurocritical care is a new subspecialty field in medicine that intersects with many of the neuroscience and critical care specialties, and continues to evolve in its scope of practice and practitioners. The objective of this study was to assess the perceived need for and roles of neurocritical care intensivists and neurointensive care units among physicians involved with intensive care and the neurosciences. An online survey of physicians practicing critical care medicine, and neurology was performed during the 2008 Leapfrog initiative to formally recognize neurocritical care training. The survey closed in July 2009 and achieved a 13% response rate (980/7524 physicians surveyed). Survey respondents (mostly from North America) included 362 (41.4%) neurologists, 164 (18.8%) internists, 104 (11.9%) pediatric intensivists, 82 (9.4%) anesthesiologists, and 162 (18.5%) from other specialties. Over 70% of respondents reported that the availability of neurocritical care units staffed with neurointensivists would improve the quality of care of critically ill neurological/neurosurgical patients. Neurologists were reported as the most appropriate specialty for training in neurointensive care by 53.3%, and 57% of respondents responded positively that neurology residency programs should offer a separate training track for those interested in neurocritical care. Broad level of support exists among the survey respondents (mostly neurologists and intensivists) for the establishment of neurological critical care units. Since neurology remains the predominant career path from which to draw neurointensivists, there may be a role for more comprehensive neurointensive care training within neurology residencies or an alternative training track for interested residents.
Neurocritical Care, 2008
To investigate the impact of statins on perihematomal edema following spontaneous supratentorial ... more To investigate the impact of statins on perihematomal edema following spontaneous supratentorial intracerebral hemorrhage (ICH). Hematoma expansion and evolution of perihematomal edema are most commonly responsible for neurological deterioration following ICH. A possible role of statins in reducing perihematomal edema has been suggested based on studies in animal models. Records of consecutive ICH patients admitted to The Johns Hopkins Hospital from 1999 to 2006 were reviewed. Patients with ICH related to trauma or underlying lesions (e.g., brain tumors, aneurysms, and arterio-venous malformations) and of infratentorial location were excluded. Absolute and relative perihematomal edema were assessed on initial head CT. Using regression analysis, the impact of prior statin use on absolute and relative edema at presentation was assessed correcting for other factors possibly impacting perihematomal edema, such as age, coagulopathy, aspirin use, admission mean arterial pressure (MAP), and blood glucose. A total of 125 consecutive ICH patients were studied. Patients with prior statin exposure had a mean edema volume of 13.2 +/- 9.2 cc compared to 22.3 +/- 18.3 cc in patients who were not using statins at the time of ICH. Following multiple linear regression analysis, we have identified a statistically significant association between prior statin use with reduced early absolute perihematomal edema (P = 0.035). Mean relative perihematomal edema was significantly lower in patients on statins at presentation (0.44) as opposed to 0.81 in patients with no prior statin use. This difference remained statistically significant (P = 0.021) after correcting for other variables. We report the association between statin use prior to ICH and decreased absolute and relative perihematomal edema. A prospective study analyzing the role of statins in perihematomal edema reduction and the resultant effect on mortality and functional outcomes following ICH is warranted.
Neurocritical Care, 2008
To assess the impact of blood glucose, coagulopathy, seizures and prior statin and aspirin use on... more To assess the impact of blood glucose, coagulopathy, seizures and prior statin and aspirin use on clinical outcome following intracerebral hemorrhage (ICH). Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes with mortality rates approaching 50%. Glasgow Coma Scale (GCS), ICH volume, age, pulse pressure, ICH location, intraventricular hemorrhage (IVH) and hydrocephalus are known to impact 30-day survival following ICH and are included in various prediction models. The role of other clinical variables in the long-term outcome of these patients is less clear. Records of consecutive ICH patients admitted to The Johns Hopkins Hospital from 1999 to 2006 were reviewed. Patients with ICH related to trauma or underlying lesions (e.g. brain tumors, aneurysms, arterio-venous malformations) and of infratentorial location were excluded. The impact of admission blood glucose, coagulopathy, seizures on presentation and prior statin and aspirin use on 30-day mortality and functional outcomes at discharge was assessed using dichotomized Modified Rankin Scale (dMRS) and Glasgow Outcomes scale (dGOS). Other variables known to impact outcomes that were included in the multiple logistic regression analysis were age, admission GCS, pulse pressure, ICH volume, ICH location, volume of IVH and hydrocephalus. A total of 314 patients with ICH were identified, 125 met inclusion criteria. Patients&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; age ranged from 34 to 90 years (mean 63.5), 57.6 % were male. Mean ICH volume was 32.09 cc (range 1-214 cc). Following multiple logistic regression analysis, prior statin use (P = 0.05) was found to be associated with decreased mortality with a greater than 12-fold odds of survival while admission blood glucose (P = 0.023) was associated with increased 30-day mortality. Coagulopathy, seizures on presentation, and prior aspirin use had no significant impact on 30-day mortality or outcomes at discharge in our study cohort. The significant association of prior statin use with decreased mortality warrants prospective evaluation of the use of statins following ICH.
Journal of Neurosurgical Anesthesiology, 2003
Traumatic spinal cord injury is frequently associated with brain injury and with alterations in r... more Traumatic spinal cord injury is frequently associated with brain injury and with alterations in respiratory and cardiovascular function that require critical care management. Complications include respiratory failure, atelectasis, pneumonia, neurogenic shock, autonomic dysreflexia, venous thromboembolism, and sepsis. While complications may be managed with supportive care, the goal of ameliorating neurologic outcome has proved elusive. Methylprednisolone, when instituted <8 hours after traumatic spinal cord injury, was associated in two clinical trials with statistically significant improvements in motor scores at 6 months and 1 year; however, critical reappraisal of these data raises questions about their validity and clinical relevance. Until more evidence of clinically effective therapies is available, acute management must be driven by pathophysiologic principles, with emphasis on interventions that attenuate secondary neurologic injury; these include the rational use of immobilization, cautious airway management, and promotion of cord perfusion and oxygenation with the appropriate level of hemodynamic and respiratory support. Clinical trials of pharmacologic neuroprotection have yielded disappointing results, but the ongoing elucidation of spinal cord repair and regenerative mechanisms suggests new therapeutic prospects.
Journal of Neurosurgical Anesthesiology, 2001
Analysis of patient data from a new neuroscience intensive care unit (NSICU) permitted evaluation... more Analysis of patient data from a new neuroscience intensive care unit (NSICU) permitted evaluation of whether such a specialty ICU favorably altered clinical outcomes in critically ill neuroscience patients, and whether such a care model produced an efficient use of resources. A retrospective review was performed to compare (1) the clinical outcomes, as defined by percent mortality and disposition at discharge, between patients with a primary diagnosis of intracerebral hemorrhage treated in 1995 in medical or surgical ICUs and those treated in the same medical facility in an NSICU in 1997; and (2) the efficiency of care, as defined by length of ICU stay, total cost of care, and specific resource use, between patients treated in the NSICU and national benchmark standards for general ICUs during the 1997 fiscal year (FY). In the latter, extracted patient population data on neurosurgery patients requiring ICU treatment during FY 1997 were used with the following adjacent-disease related group (A-DRG)-coded diseases: craniotomy with and without coma or intracerebral hemorrhage, and skull fracture with and without coma lasting longer than 1 hour. Outcome measures of percent mortality and disposition at discharge in patients with intracerebral hemorrhage were significantly improved (P < .05), compared with those in a similar cohort treated 2 years earlier in a general ICU setting. Also, patients treated in the NSICU had shorter hospital stays (P < .01 ) and lower total costs of care (P < .01) than a national benchmark. The data suggest that a neuroscience specialty ICU arena staffed by specialty-trained intensivists and nurses is beneficial.
Journal of Neurosurgery, 2007
Opioid administration after major intracranial surgery is often limited by a presumed lack of nee... more Opioid administration after major intracranial surgery is often limited by a presumed lack of need and a concern that opioids will adversely affect the postoperative neurological examination. The authors conducted a prospective study to evaluate the incidence, severity, and treatment of postoperative pain in patients who underwent major intracranial surgery. One hundred eighty-seven patients (77 men and 110 women, mean age 52 +/- 15 years, mean weight 78.1 +/- 19.9 kg) underwent either supratentorial (129 patients) or infratentorial (58 patients) procedures. Sixty-nine percent of the patients reported experiencing moderate to severe pain (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; or =4 on a 0-10 scale) during the 1st postoperative day. Pain scores greater than or equal to 4 persisted in 48% on the 2nd postoperative day. Approximately 80% of patients were treated with acetaminophen on the 1st postoperative day, whereas opioids (primarily intravenous fentanyl) were administered to 58%. Compared with patients who underwent supratentorial procedures, those who underwent infratentorial procedures reported more severe pain at rest (mean score 4.9 +/- 2.2 compared with 3.8 +/- 2.6; p = 0.015) and with movement (mean score 6.3 +/- 2.6 compared with 4.5 +/- 2.7; p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) on the 1st postoperative day. On both the 1st and 2nd postoperative days, patients who underwent infratentorial procedures received greater quantities of opioid (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 0.019) and nonopioid (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 0.013) analgesics than those who underwent supratentorial procedures. Patients&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; dissatisfaction with analgesic therapy was significantly associated with elevated pain levels on the first 2 postoperative days (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). In contrast to prevailing assumptions, the study findings reveal that most patients undergoing elective major intracranial surgery will experience moderate to severe pain for the first 2 days after surgery and that this pain is often inadequately treated.
Journal of Clinical Anesthesia, 2006
To evaluate the effect of 0.25% bupivacaine scalp block on alterations in hemodynamics and plasma... more To evaluate the effect of 0.25% bupivacaine scalp block on alterations in hemodynamics and plasma catecholamine metabolites during general anesthesia in patients undergoing frontotemporal craniotomy. Prospective, clinical study. Operating room of a university hospital. 16 ASA physical status II and III patients who were scheduled for frontotemporal craniotomy. Patients were prospectively randomized to receive a saline control (C group) or bupivacaine scalp block (SB group) as an adjuvant to general anesthesia using isoflurane in 50% N(2)O-O(2). Routine monitoring of electrocardiogram, heart rate (HR), and mean arterial blood pressure (MAP) were recorded at two-minute intervals from the beginning of anesthesia until 10 minutes after incision, followed by 5-minute intervals throughout the remaining course of the surgery. By prospective design, increases in MAP or HR by 20% above the mean baseline values were treated with 2.5 mg/kg of thiopental combined with 2 mug/kg of fentanyl. Arterial blood was sampled at 5 minutes before and after skin incision and at the start of dural opening for measuring serum catecholamine metabolites by high-performance liquid chromatography. Only two patients in the SB group needed additional anesthetics for stabilizing their hemodynamics during the course of anesthesia. In contrast, all C group patients required supplemental anesthesia for controlling the abrupt rise in hemodynamic parameters. In addition, absolute MAP and HR values were significantly higher in the C group than in the SB group during the surgical period between incision and dural opening. The differences in hemodynamics observed between the two groups were, however, not accompanied with a significant change in plasma catecholamine metabolites at each predetermined time interval measured. Pretreatment with 0.25% bupivacaine scalp block appeared to be an effective adjuvant treatment for maintaining stable hemodynamics for patients undergoing craniotomy during general anesthesia especially at the time of skin incision and dural opening. This study design was unable to discern any correlation between elevation in hemodynamic parameters and a rise in serum catecholamine levels.
Intensive Care Medicine, 2010
DEX may be a consequence of the intellect-sparing yet calming effect of this drug.
Intensive Care Medicine, 2009
IEEE Transactions on Biomedical Engineering, 2003
Our proposed algorithm for seizure prediction is based on the principle that seizure build-up is ... more Our proposed algorithm for seizure prediction is based on the principle that seizure build-up is always preceded by constantly changing bursting levels. We use a novel measure of residual subband wavelet entropy (RSWE) to directly estimate the entropy of bursts, which is otherwise obscured by the ongoing background activity. Our results are obtained using a slow infusion anesthetized pentylenetetrazol (PTZ) rat model in which we record field potentials (FPs) from frontal cortex and two thalamic areas (anterior and posterior nuclei). In each frequency band, except for the theta-delta frequency bands, we observed a significant build-up of RSWE from the preictal period to the first ictal event (p 0.05) in cortex. Significant differences were observed between cortical and thalamic RSWE (p 0.05) subsequent to seizure development. A key observation is the twofold increase in mean cortical RSWE from the preictal to interictal period. Exploiting this increase, we develop a slope change detector to discern early acceleration of entropy and predict the approaching seizure. We use multiple observations through sequential detection of slope changes to enhance the sensitivity of our prediction. Using the proposed method applied to a cohort of four rats subjected to PTZ infusion, we were able to predict the first seizure episode 28 min prior to its occurrence.
Epilepsy Research, 1997
Evidence suggests that a specific subcortical pathway synaptically linking the anterior thalamic ... more Evidence suggests that a specific subcortical pathway synaptically linking the anterior thalamic nuclear complex (AN) to the hypothalamus and midbrain is important in the expression of pentylenetetrazol (PTZ) seizures. Perturbation of neuronal activity along this path via focal disruption or chemical inhibition significantly raises seizure threshold. Recent data has demonstrated that focal electrical stimulation within the hypothalamic component of this pathway inhibited seizure expression in a current and frequency dependent fashion. Similar experiments were conducted in the AN to investigate the hypothesis that stimulation of this thalamic nuclear region can prevent the propagation of PTZ seizures between cortical and subcortical regions. Our results indicate that high frequency (100 Hz) stimulation of AN did not alter the expression of low dose PTZ induced cortical bursting but did raise the clonic seizure threshold compared to naive animals or those stimulated at sites near, but not in AN (P < 0.01). Low frequency stimulation (8 Hz) was in contrast, proconvulsant and could induce behavioral arrest responses accompanied by rhythmic high voltage EEG even without PTZ challenge. This data further highlights the role of AN in mediating the expression of seizures and provides experimental support for the concept that this thalamic region may be a promising target for focal stimulation to treat intractable seizures in humans.