Ramez Kirollos - Academia.edu (original) (raw)

Papers by Ramez Kirollos

British Journal of Neurosurgery, 1998

As surgery alone may prove inadequate to effect a cure for invasive pituitary adenomas, photodyna... more As surgery alone may prove inadequate to effect a cure for invasive pituitary adenomas, photodynamic therapy (PDT) was investigated as a possible adjuvant treatment for this group of tumours. Different subtypes of human pituitary adenoma cells were implanted subcutaneously into nude mice to study the in vivo effect of PDT on such lesions. The photosensitizer used in this study was polyhaematoporphyrin at a dose of 10 mg/kg b.w., followed by light irradiation at a wavelength of 630 nm with varying light doses between 10 and 75 J/cm2. Histopathological examination of the treated implants consistently showed tumour vascular changes with acute inflammatory reaction, interstitial haemorrhage, and evidence of cell death at higher doses of light. These changes were absent in the control groups. These findings indicate that the cytotoxic effect of PDT demonstrated in vitro in previous studies, is also present in vivo.

CRC Press eBooks, Feb 17, 2023

CRC Press eBooks, Feb 17, 2023

CRC Press eBooks, Feb 17, 2023

Operative Neurosurgery, Nov 29, 2021

Upper cervical schwannomas are rare lesions and together with meningiomas constitute around 5% of... more Upper cervical schwannomas are rare lesions and together with meningiomas constitute around 5% of spinal tumors. The approach to these lesions is difficult because of the close proximity of the medulla and cervical spinal cord, lower cranial nerves, and the vertebral artery. Schwannomas in the upper cervical area typically arise from the dorsal roots and are located posterior to the dentate ligament. Nevertheless, a far lateral approach is often required for these lesions because of their lateral extent through the neural foramen and the proximity of both the V3 and V4 segments of the vertebral artery. With these lesions, an extensive condylectomy is rarely required. We present a case of a 40-yr-old woman who presented with an 8-mo history of deteriorating mobility and feeling of heaviness in the lower limbs with a further acute deterioration 1 wk before admission. She had a dissociated sensory loss and myelopathy in keeping with a partial hemicord syndrome. Imaging revealed a right-sided C2 intradural lesion extending through the C2 foramen in keeping with a C2 schwannoma. The patient was counseled on the treatment options, and informed consent for surgery was obtained. We describe a right-sided far lateral approach with minimal condylectomy for gross total resection of this lesion. We demonstrate the relationship of the tumor with the C2 nerve root, the spinal accessory nerve, and the cervical cord. We supplement the discussion with a 3D surgical video.

World Neurosurgery, Jun 1, 2020

Operative Neurosurgery, Jun 4, 2019

Cavernous malformations (cavernomas) of the brain stem with recurrent hemorrhage may be amenable ... more Cavernous malformations (cavernomas) of the brain stem with recurrent hemorrhage may be amenable to microsurgical resection if they are present close to the surface. The risks of surgery need to be balanced with the natural history of the lesion and the accumulation of neurological deficits and risk to life with multiple hemorrhages. In this 3D operative video, we illustrate the technique for the resection of a dorsally located midbrain cavernous malformation. Informed consent was obtained for this procedure. The cavernoma is accessed with the use of a supracerebellar infratentorial approach. The infratentorial craniotomy and coagulation of the superior vermian veins is shown. A description is provided of the use of hemosiderin staining and the intercollicular relative “safe zone” 1 as landmarks for the neurotomy. The technique of cavernoma dissection from the surrounding gliotic plane is shown and described. In this case, the patient required prolonged rehabilitation but fully recovered without residual deficit 1 yr following surgery.

British Journal of Neurosurgery, 1995

We report an 18-year-old patient who presented with delayed neurological deterioration secondary ... more We report an 18-year-old patient who presented with delayed neurological deterioration secondary to posttraumatic cerebellar infarction. Management by ventricular drainage and posterior fossa decompression resulted in a good outcome. The absence of a demonstrable structural vascular lesion makes this case apparently unique. The possible aetiology, pathogenesis and management of this condition are discussed.

CRC Press eBooks, Feb 17, 2023

CRC Press eBooks, Feb 17, 2023

Journal of Neurology and Neurophysiology, Sep 4, 2017

Objective: Primary pontine haemorrhage is the most devastating form of haemorrhagic stroke accoun... more Objective: Primary pontine haemorrhage is the most devastating form of haemorrhagic stroke accounting for about 10% of intracerebral haemorrhages with an overall mortality rate of 40-50% as reported in the literature. There are various factors reported to have an association with outcome such[for full text, please go to the a.m. URL]

Anesthesiology, 2010

Background Although hypothermia and barbiturates improve neurologic outcomes in animal temporary ... more Background Although hypothermia and barbiturates improve neurologic outcomes in animal temporary focal ischemia models, the clinical efficacy of these interventions during temporary occlusion of the cerebral vasculature during intracranial aneurysm surgery (temporary clipping) is not established. Methods A post hoc analysis of patients from the Intraoperative Hypothermia for Aneurysm Surgery Trial who underwent temporary clipping was performed. Univariate and multivariate logistic regression methods were used to test for associations between hypothermia, supplemental protective drug, and short- (24-h) and long-term (3-month) neurologic outcomes. An odds ratio more than 1 denotes better outcome. Results Patients undergoing temporary clipping (n = 441) were assigned to intraoperative hypothermia (33.3 degrees +/- 0.8 degrees C, n = 208) or normothermia (36.7 degrees +/- 0.5 degrees C, n = 233), with 178 patients also receiving supplemental protective drug (thiopental or etomidate) dur...

World Neurosurgery, Aug 1, 2023

Operative Neurosurgery, Dec 1, 2013

BACKGROUND: The aqueduct of Sylvius (AqSylv) is a structure of increasing importance in neuroendo... more BACKGROUND: The aqueduct of Sylvius (AqSylv) is a structure of increasing importance in neuroendoscopic procedures. However, there is currently no clear and adequate description of the normal anatomy of the AqSylv. OBJECTIVE: To study in detail hitherto unavailable normal magnetic resonance imaging morphometry and anatomic variants of the AqSylv. METHODS: We retrospectively studied normal midsagittal T1-weighted 3-T magnetic resonance images in 100 patients. We measured widths of the AqSylv pars anterior, ampulla, and pars posterior; its narrowest point; and its length. We recorded angulation of the AqSylv relative to the third ventricle as multiple deviations of the long axis of the AqSylv from the Talairach bicommissural line. We statistically determined age- and sex-related changes in AqSylv morphometry using the Pearson correlation coefficient. We measured angulation of the AqSylv relative to the fourth ventricle and correlated this to the cervicomedullary angle (a surrogate for head position). RESULTS: Patients were 13 to 83 years of age (45% male, 55% female). Mean morphometrics were as follows: pars anterior width, 1.1 mm; ampulla width, 1.2 mm; pars posterior width, 1.4 mm; length, 14.1 mm; narrowest point, 0.9 mm; and angulation in relation to the third and fourth ventricles, 26° and 18°, respectively. Age correlated positively with width and negatively with length of the AqSylv. There was no correlation between AqSylv alignment relative to the foramen magnum and the cervicomedullary angle. CONCLUSION: Normative dimensions of the AqSylv in vivo are at variance with published cadaveric morphometrics. The AqSylv widens and shortens with cerebral involution. Awareness of these normal morphometrics is highly useful when stent placement is an option during aqueductoplasty. Reported data are valuable in guiding neuroendoscopic management of hydrocephalus and aqueductal stenosis.

CRC Press eBooks, Nov 10, 2014

European Spine Journal, Jun 2, 1999

British Journal of Neurosurgery, 1996

A new grading system is presented to assess the degree of untethering achieved at surgery for the... more A new grading system is presented to assess the degree of untethering achieved at surgery for the 'tethered cord syndrome' based on intraoperative observation at the end of the procedure. Various pathophysiological mechanisms responsible for the 'tethered cord syndrome', as well as possible factors causing retethering were considered in developing this grading system. In Grade I the cord is considered to be fully untethered and the factors potentially responsible for retethering are eliminated, in Grade II partial untethering is performed and in Grade III untethering is unsuccessful. This grading system was used to assess the results of 22 consecutive operations performed to release a tethered cord between June 1991 and February 1995. The tethering factors encountered at surgery were: spinal lipoma in 14, diastematomyelia in five, a tight filum terminale in 10 and intradural adhesions in three instances. The grade of untethering was correlated with the type of pathology encountered, postoperative results, and whether previous surgery was performed or not. Previous surgery was found not to affect the rate of subsequent successful untethering.

British Journal of Neurosurgery, 1998

As surgery alone may prove inadequate to effect a cure for invasive pituitary adenomas, photodyna... more As surgery alone may prove inadequate to effect a cure for invasive pituitary adenomas, photodynamic therapy (PDT) was investigated as a possible adjuvant treatment for this group of tumours. Different subtypes of human pituitary adenoma cells were implanted subcutaneously into nude mice to study the in vivo effect of PDT on such lesions. The photosensitizer used in this study was polyhaematoporphyrin at a dose of 10 mg/kg b.w., followed by light irradiation at a wavelength of 630 nm with varying light doses between 10 and 75 J/cm2. Histopathological examination of the treated implants consistently showed tumour vascular changes with acute inflammatory reaction, interstitial haemorrhage, and evidence of cell death at higher doses of light. These changes were absent in the control groups. These findings indicate that the cytotoxic effect of PDT demonstrated in vitro in previous studies, is also present in vivo.

CRC Press eBooks, Feb 17, 2023

CRC Press eBooks, Feb 17, 2023

CRC Press eBooks, Feb 17, 2023

Operative Neurosurgery, Nov 29, 2021

Upper cervical schwannomas are rare lesions and together with meningiomas constitute around 5% of... more Upper cervical schwannomas are rare lesions and together with meningiomas constitute around 5% of spinal tumors. The approach to these lesions is difficult because of the close proximity of the medulla and cervical spinal cord, lower cranial nerves, and the vertebral artery. Schwannomas in the upper cervical area typically arise from the dorsal roots and are located posterior to the dentate ligament. Nevertheless, a far lateral approach is often required for these lesions because of their lateral extent through the neural foramen and the proximity of both the V3 and V4 segments of the vertebral artery. With these lesions, an extensive condylectomy is rarely required. We present a case of a 40-yr-old woman who presented with an 8-mo history of deteriorating mobility and feeling of heaviness in the lower limbs with a further acute deterioration 1 wk before admission. She had a dissociated sensory loss and myelopathy in keeping with a partial hemicord syndrome. Imaging revealed a right-sided C2 intradural lesion extending through the C2 foramen in keeping with a C2 schwannoma. The patient was counseled on the treatment options, and informed consent for surgery was obtained. We describe a right-sided far lateral approach with minimal condylectomy for gross total resection of this lesion. We demonstrate the relationship of the tumor with the C2 nerve root, the spinal accessory nerve, and the cervical cord. We supplement the discussion with a 3D surgical video.

World Neurosurgery, Jun 1, 2020

Operative Neurosurgery, Jun 4, 2019

Cavernous malformations (cavernomas) of the brain stem with recurrent hemorrhage may be amenable ... more Cavernous malformations (cavernomas) of the brain stem with recurrent hemorrhage may be amenable to microsurgical resection if they are present close to the surface. The risks of surgery need to be balanced with the natural history of the lesion and the accumulation of neurological deficits and risk to life with multiple hemorrhages. In this 3D operative video, we illustrate the technique for the resection of a dorsally located midbrain cavernous malformation. Informed consent was obtained for this procedure. The cavernoma is accessed with the use of a supracerebellar infratentorial approach. The infratentorial craniotomy and coagulation of the superior vermian veins is shown. A description is provided of the use of hemosiderin staining and the intercollicular relative “safe zone” 1 as landmarks for the neurotomy. The technique of cavernoma dissection from the surrounding gliotic plane is shown and described. In this case, the patient required prolonged rehabilitation but fully recovered without residual deficit 1 yr following surgery.

British Journal of Neurosurgery, 1995

We report an 18-year-old patient who presented with delayed neurological deterioration secondary ... more We report an 18-year-old patient who presented with delayed neurological deterioration secondary to posttraumatic cerebellar infarction. Management by ventricular drainage and posterior fossa decompression resulted in a good outcome. The absence of a demonstrable structural vascular lesion makes this case apparently unique. The possible aetiology, pathogenesis and management of this condition are discussed.

CRC Press eBooks, Feb 17, 2023

CRC Press eBooks, Feb 17, 2023

Journal of Neurology and Neurophysiology, Sep 4, 2017

Objective: Primary pontine haemorrhage is the most devastating form of haemorrhagic stroke accoun... more Objective: Primary pontine haemorrhage is the most devastating form of haemorrhagic stroke accounting for about 10% of intracerebral haemorrhages with an overall mortality rate of 40-50% as reported in the literature. There are various factors reported to have an association with outcome such[for full text, please go to the a.m. URL]

Anesthesiology, 2010

Background Although hypothermia and barbiturates improve neurologic outcomes in animal temporary ... more Background Although hypothermia and barbiturates improve neurologic outcomes in animal temporary focal ischemia models, the clinical efficacy of these interventions during temporary occlusion of the cerebral vasculature during intracranial aneurysm surgery (temporary clipping) is not established. Methods A post hoc analysis of patients from the Intraoperative Hypothermia for Aneurysm Surgery Trial who underwent temporary clipping was performed. Univariate and multivariate logistic regression methods were used to test for associations between hypothermia, supplemental protective drug, and short- (24-h) and long-term (3-month) neurologic outcomes. An odds ratio more than 1 denotes better outcome. Results Patients undergoing temporary clipping (n = 441) were assigned to intraoperative hypothermia (33.3 degrees +/- 0.8 degrees C, n = 208) or normothermia (36.7 degrees +/- 0.5 degrees C, n = 233), with 178 patients also receiving supplemental protective drug (thiopental or etomidate) dur...

World Neurosurgery, Aug 1, 2023

Operative Neurosurgery, Dec 1, 2013

BACKGROUND: The aqueduct of Sylvius (AqSylv) is a structure of increasing importance in neuroendo... more BACKGROUND: The aqueduct of Sylvius (AqSylv) is a structure of increasing importance in neuroendoscopic procedures. However, there is currently no clear and adequate description of the normal anatomy of the AqSylv. OBJECTIVE: To study in detail hitherto unavailable normal magnetic resonance imaging morphometry and anatomic variants of the AqSylv. METHODS: We retrospectively studied normal midsagittal T1-weighted 3-T magnetic resonance images in 100 patients. We measured widths of the AqSylv pars anterior, ampulla, and pars posterior; its narrowest point; and its length. We recorded angulation of the AqSylv relative to the third ventricle as multiple deviations of the long axis of the AqSylv from the Talairach bicommissural line. We statistically determined age- and sex-related changes in AqSylv morphometry using the Pearson correlation coefficient. We measured angulation of the AqSylv relative to the fourth ventricle and correlated this to the cervicomedullary angle (a surrogate for head position). RESULTS: Patients were 13 to 83 years of age (45% male, 55% female). Mean morphometrics were as follows: pars anterior width, 1.1 mm; ampulla width, 1.2 mm; pars posterior width, 1.4 mm; length, 14.1 mm; narrowest point, 0.9 mm; and angulation in relation to the third and fourth ventricles, 26° and 18°, respectively. Age correlated positively with width and negatively with length of the AqSylv. There was no correlation between AqSylv alignment relative to the foramen magnum and the cervicomedullary angle. CONCLUSION: Normative dimensions of the AqSylv in vivo are at variance with published cadaveric morphometrics. The AqSylv widens and shortens with cerebral involution. Awareness of these normal morphometrics is highly useful when stent placement is an option during aqueductoplasty. Reported data are valuable in guiding neuroendoscopic management of hydrocephalus and aqueductal stenosis.

CRC Press eBooks, Nov 10, 2014

European Spine Journal, Jun 2, 1999

British Journal of Neurosurgery, 1996

A new grading system is presented to assess the degree of untethering achieved at surgery for the... more A new grading system is presented to assess the degree of untethering achieved at surgery for the 'tethered cord syndrome' based on intraoperative observation at the end of the procedure. Various pathophysiological mechanisms responsible for the 'tethered cord syndrome', as well as possible factors causing retethering were considered in developing this grading system. In Grade I the cord is considered to be fully untethered and the factors potentially responsible for retethering are eliminated, in Grade II partial untethering is performed and in Grade III untethering is unsuccessful. This grading system was used to assess the results of 22 consecutive operations performed to release a tethered cord between June 1991 and February 1995. The tethering factors encountered at surgery were: spinal lipoma in 14, diastematomyelia in five, a tight filum terminale in 10 and intradural adhesions in three instances. The grade of untethering was correlated with the type of pathology encountered, postoperative results, and whether previous surgery was performed or not. Previous surgery was found not to affect the rate of subsequent successful untethering.