Tahani Ahmad | Dalhousie University (original) (raw)
Papers by Tahani Ahmad
Pediatric brain tumors are the most common type of solid childhood cancer and only second to leuk... more Pediatric brain tumors are the most common type of solid childhood cancer and only second to leukemia as a cause of pediatric malignancies. They are classified into supra and infratentorial tumors. They could also be classified according to the age of diagnosis into congenital brain tumors (CBT) (diagnosed antenatally in the first 60 days of life), tumors of the infancy (younger than 1 year of age), and older children. The prognosis of pediatric brain tumors depends on the age at presentation, histological type, and extent of resection. CBT behaves in different ways than pathologically similar tumors in older children. For example, high-grade gliomas exhibit sightly better prognosis in very young children compared to their older counterparts. With the advances in imaging techniques, molecular biology, and genetics, pediatric brain tumors are increasingly being diagnosed early in the disease course, sub-grouped, and treated with more targeted strategies.Among all childhood cancers, brain tumors are the leading cause of death.This article highlights the congenital group with an emphasis on the most common types in this category, specifically; teratoma, choroid plexus papilloma, desmoplastic infantile tumors (DIA/DIG), glioblastoma multiforme (GBM), and medulloblastoma.
Neuro-oncology advances, 2022
StatPearls Publishing, Aug 12, 2021
StatPearls Publishing, Dec 4, 2020
There are two varieties of polycystic kidney disease based on inheritance: autosomal dominant (AD... more There are two varieties of polycystic kidney disease based on inheritance: autosomal dominant (ADPKD) and autosomal recessive (ARPKD) types. These two forms have distinct clinical and genetic features. ADPKD is a multisystem progressive cystic disorder. It is characterized by bilateral renal cysts, which progressively leads to fibrosis and architectural distortion of kidneys and progressive renal failure.[[1] Other organs such as the liver, pancreas, and spleen can also be involved. These patients also have a higher risk of developing aneurysms along the circle of Willis than the general populations. In adult patients, it is the most frequent genetic cause of renal failure. It accounts for 5% of patients on dialysis in the United States.[[2] Nearly 50% of patients with ADPKD progresses to end-stage renal disease by the age of 65 years.[3] ARPKD primarily involves kidney and liver. Historically, referred to as infantile polycystic kidney disease, however, with the current knowledge a...
Pediatric brain tumors are the most common type of solid childhood cancer and only second to leuk... more Pediatric brain tumors are the most common type of solid childhood cancer and only second to leukemia as a cause of pediatric malignancies. They are classified into supra and infratentorial tumors. They could also be classified according to the age of diagnosis into congenital brain tumors (CBT) (diagnosed antenatally in the first 60 days of life), tumors of the infancy (younger than 1 year of age), and older children. The prognosis of pediatric brain tumors depends on the age at presentation, histological type, and extent of resection. CBT behaves in different ways than pathologically similar tumors in older children. For example, high-grade gliomas exhibit sightly better prognosis in very young children compared to their older counterparts. With the advances in imaging techniques, molecular biology, and genetics, pediatric brain tumors are increasingly being diagnosed early in the disease course, sub-grouped, and treated with more targeted strategies.Among all childhood cancers, b...
There are two varieties of polycystic kidney disease based on inheritance: autosomal dominant (AD... more There are two varieties of polycystic kidney disease based on inheritance: autosomal dominant (ADPKD) and autosomal recessive (ARPKD) types. These two forms have distinct clinical and genetic features. ADPKD is a multisystem progressive cystic disorder. It is characterized by bilateral renal cysts, which progressively leads to fibrosis and architectural distortion of kidneys and progressive renal failure.[[1] Other organs such as the liver, pancreas, and spleen can also be involved. These patients also have a higher risk of developing aneurysms along the circle of Willis than the general populations. In adult patients, it is the most frequent genetic cause of renal failure. It accounts for 5% of patients on dialysis in the United States.[[2] Nearly 50% of patients with ADPKD progresses to end-stage renal disease by the age of 65 years.[3] ARPKD primarily involves kidney and liver. Historically, referred to as infantile polycystic kidney disease, however, with the current knowledge about the genetic basis of disease and clinical manifestation, it can present as infantile, juvenile or even in the adult population. Hence old nomenclature of adult and infantile polycystic kidney disease is not used anymore.[4] It is characterized by renal collecting duct ectasia, hepatic biliary duct ectasia/malformation, and fibrosis involving both liver and kidney. Cystic dilatation of renal tubules characterizes both ADPKD and ARPKD. ADPKD shows cysts of varying sizes which may show coarse calcifications and renal calculi. Cysts in ARPKD are mostly microcystic. Cysts in ADPKD can arise from anywhere along the nephron, most commonly from collecting tube. However, cysts in ARPKD arise exclusively in the collecting tubule.
Dandy-Walker malformation (DWM) or syndrome is a posterior fossa anomaly characterized by agenesi... more Dandy-Walker malformation (DWM) or syndrome is a posterior fossa anomaly characterized by agenesis or hypoplasia of the vermis and cystic enlargement of the fourth ventricle causing upward displacement of tentorium and torcula. Most patients have hydrocephalus at the time of diagnosis. DMW is the most common posterior fossa malformation, and it typically occurs sporadically.Many patients remain clinically asymptomatic for years, while others may present with a variety of comorbidities leading to earlier diagnosis. Treatment is generally focused on alleviating hydrocephalus and posterior fossa symptoms, often including surgical interventions like ventriculoperitoneal and cystoperitoneal shunting.
Paediatrics & Child Health
Objective The goal of this study was to obtain population-based data on the incidence, clinical p... more Objective The goal of this study was to obtain population-based data on the incidence, clinical presentation, management, imaging features, and long-term outcomes of patients with all types of neonatal stroke (NS). Methods Full-term neonates with NS born between January 2007 and December 2013 were identified through the Nova Scotia Provincial Perinatal Follow-up Program Database. Perinatal data and neonatal course were reviewed. Neurodevelopmental outcomes were assessed at 18 and 36 months of age using standardized testing. Results Twenty-nine neonates with NS were identified during the study period, giving an incidence of 47 per 100,000 live births in Nova Scotia. Arterial ischemic stroke was the most common stroke type (76%), followed by neonatal hemorrhagic stroke (17%), then cerebral sinovenous thrombosis (7%). The majority of neonates presented with seizures (86%) on the first day of life (76%). At 36 months of age, 23 (79%) of the children had a normal outcome, while 3 (10%) w...
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques
American Journal of Roentgenology
Pe d i a t r ic I m ag i ng • O r ig i n a l R e s e a rc h This article is available for credit.
Pediatric Neurosurgery
Arachnoid cysts (ACs) are frequently encountered in pediatric neurosurgical practice. Their natur... more Arachnoid cysts (ACs) are frequently encountered in pediatric neurosurgical practice. Their natural history and optimum treatment are not well determined. The authors describe a resolution of asymptomatic middle fossa AC after trivial head trauma in a 7-year-old child. Intracystic bleeding was noticed on interval MRI. Serial MRI follow-up demonstrates stages of resolution of the AC that did not require surgical intervention. Few cases of nonsurgical AC disappearance have been reported, much fewer with trauma as a triggering factor. Here, we present the stages of resolution in images.
Jordan Medical Journal, Jul 22, 2010
Pediatric neurosurgery, Jan 16, 2016
Dysembryoplastic neuroepithelial tumors (DNETs) are generally considered benign, slow-growing epi... more Dysembryoplastic neuroepithelial tumors (DNETs) are generally considered benign, slow-growing epilepsy-associated lesions. While rare cases of malignant transformation of DNET to high-grade glial tumors have been reported, to our knowledge there have been no reports of transformation/emergence of DNET to atypical teratoid rhabdoid tumor (AT/RT), a highly aggressive embryonal brain tumor. Here, we report the case of an 8-year-old boy who presented with an incidental finding of a small right insular lesion which grew slowly over 3 years. The patient first underwent surgery with subtotal tumor resection at age 11. Pathology was consistent with DNET. Following surgery, further tumor growth was evident, requiring fractionated radiotherapy and eventually chemotherapy, but continued tumor growth was witnessed. Three years after radiation, imaging showed dramatic further tumor growth, and the patient underwent a second debulking surgery. The pathology revealed a malignant tumor with BAF47-n...
American Journal of Roentgenology, 2016
The objective of this study was to assess the diagnostic agreement between bowel sonography and M... more The objective of this study was to assess the diagnostic agreement between bowel sonography and MR enterography in children with suspected or confirmed inflammatory bowel disease (IBD). We prospectively studied 33 children undergoing clinically indicated MR enterography. Bowel sonography was performed within 2 hours before MR enterography. The reliability of each modality was assessed by computing the interreader kappa agreement on nine inflammatory markers in eight bowel segments and the interreader intraclass correlation coefficients (ICC) in each bowel segment. The agreement between both modalities in each bowel segment was also calculated using the Kendall coefficient of concordance (KCC) in addition to the sensitivity and specificity of sonography using those of MR enterography as the reference standard. Sonographic readings are substantially reliable in the colon and terminal and distal ileum (ICC = 0.79-0.88) but are highly unreliable in the mid and proximal small bowel. MR enterography has moderate to almost perfect reliability for all bowel segments (ICC = 0.43-0.96). Sonography was in substantial agreement with MR enterography in most of the large bowel (KCC = 0.67-0.83) and terminal and distal ileum (KCC = 0.75) and in moderate agreement in the remaining bowel segments (KCC = 0.45-0.48). Sonographic findings are specific for disease using MR enterography as the reference standard in all bowel segments (0.83-1.00), but sensitivity markedly varies according to disease location. Sonography is highly specific and shows substantial agreement with MR enterography in detecting inflammatory and damage changes in the colon and terminal and distal ileum, the segments most likely to be affected by IBD. Therefore, sonography can be a good complement to MR enterography in evaluations of patients with known or suspected IBD, particularly if MR enterography access is limited.
Pediatric brain tumors are the most common type of solid childhood cancer and only second to leuk... more Pediatric brain tumors are the most common type of solid childhood cancer and only second to leukemia as a cause of pediatric malignancies. They are classified into supra and infratentorial tumors. They could also be classified according to the age of diagnosis into congenital brain tumors (CBT) (diagnosed antenatally in the first 60 days of life), tumors of the infancy (younger than 1 year of age), and older children. The prognosis of pediatric brain tumors depends on the age at presentation, histological type, and extent of resection. CBT behaves in different ways than pathologically similar tumors in older children. For example, high-grade gliomas exhibit sightly better prognosis in very young children compared to their older counterparts. With the advances in imaging techniques, molecular biology, and genetics, pediatric brain tumors are increasingly being diagnosed early in the disease course, sub-grouped, and treated with more targeted strategies.Among all childhood cancers, brain tumors are the leading cause of death.This article highlights the congenital group with an emphasis on the most common types in this category, specifically; teratoma, choroid plexus papilloma, desmoplastic infantile tumors (DIA/DIG), glioblastoma multiforme (GBM), and medulloblastoma.
Neuro-oncology advances, 2022
StatPearls Publishing, Aug 12, 2021
StatPearls Publishing, Dec 4, 2020
There are two varieties of polycystic kidney disease based on inheritance: autosomal dominant (AD... more There are two varieties of polycystic kidney disease based on inheritance: autosomal dominant (ADPKD) and autosomal recessive (ARPKD) types. These two forms have distinct clinical and genetic features. ADPKD is a multisystem progressive cystic disorder. It is characterized by bilateral renal cysts, which progressively leads to fibrosis and architectural distortion of kidneys and progressive renal failure.[[1] Other organs such as the liver, pancreas, and spleen can also be involved. These patients also have a higher risk of developing aneurysms along the circle of Willis than the general populations. In adult patients, it is the most frequent genetic cause of renal failure. It accounts for 5% of patients on dialysis in the United States.[[2] Nearly 50% of patients with ADPKD progresses to end-stage renal disease by the age of 65 years.[3] ARPKD primarily involves kidney and liver. Historically, referred to as infantile polycystic kidney disease, however, with the current knowledge a...
Pediatric brain tumors are the most common type of solid childhood cancer and only second to leuk... more Pediatric brain tumors are the most common type of solid childhood cancer and only second to leukemia as a cause of pediatric malignancies. They are classified into supra and infratentorial tumors. They could also be classified according to the age of diagnosis into congenital brain tumors (CBT) (diagnosed antenatally in the first 60 days of life), tumors of the infancy (younger than 1 year of age), and older children. The prognosis of pediatric brain tumors depends on the age at presentation, histological type, and extent of resection. CBT behaves in different ways than pathologically similar tumors in older children. For example, high-grade gliomas exhibit sightly better prognosis in very young children compared to their older counterparts. With the advances in imaging techniques, molecular biology, and genetics, pediatric brain tumors are increasingly being diagnosed early in the disease course, sub-grouped, and treated with more targeted strategies.Among all childhood cancers, b...
There are two varieties of polycystic kidney disease based on inheritance: autosomal dominant (AD... more There are two varieties of polycystic kidney disease based on inheritance: autosomal dominant (ADPKD) and autosomal recessive (ARPKD) types. These two forms have distinct clinical and genetic features. ADPKD is a multisystem progressive cystic disorder. It is characterized by bilateral renal cysts, which progressively leads to fibrosis and architectural distortion of kidneys and progressive renal failure.[[1] Other organs such as the liver, pancreas, and spleen can also be involved. These patients also have a higher risk of developing aneurysms along the circle of Willis than the general populations. In adult patients, it is the most frequent genetic cause of renal failure. It accounts for 5% of patients on dialysis in the United States.[[2] Nearly 50% of patients with ADPKD progresses to end-stage renal disease by the age of 65 years.[3] ARPKD primarily involves kidney and liver. Historically, referred to as infantile polycystic kidney disease, however, with the current knowledge about the genetic basis of disease and clinical manifestation, it can present as infantile, juvenile or even in the adult population. Hence old nomenclature of adult and infantile polycystic kidney disease is not used anymore.[4] It is characterized by renal collecting duct ectasia, hepatic biliary duct ectasia/malformation, and fibrosis involving both liver and kidney. Cystic dilatation of renal tubules characterizes both ADPKD and ARPKD. ADPKD shows cysts of varying sizes which may show coarse calcifications and renal calculi. Cysts in ARPKD are mostly microcystic. Cysts in ADPKD can arise from anywhere along the nephron, most commonly from collecting tube. However, cysts in ARPKD arise exclusively in the collecting tubule.
Dandy-Walker malformation (DWM) or syndrome is a posterior fossa anomaly characterized by agenesi... more Dandy-Walker malformation (DWM) or syndrome is a posterior fossa anomaly characterized by agenesis or hypoplasia of the vermis and cystic enlargement of the fourth ventricle causing upward displacement of tentorium and torcula. Most patients have hydrocephalus at the time of diagnosis. DMW is the most common posterior fossa malformation, and it typically occurs sporadically.Many patients remain clinically asymptomatic for years, while others may present with a variety of comorbidities leading to earlier diagnosis. Treatment is generally focused on alleviating hydrocephalus and posterior fossa symptoms, often including surgical interventions like ventriculoperitoneal and cystoperitoneal shunting.
Paediatrics & Child Health
Objective The goal of this study was to obtain population-based data on the incidence, clinical p... more Objective The goal of this study was to obtain population-based data on the incidence, clinical presentation, management, imaging features, and long-term outcomes of patients with all types of neonatal stroke (NS). Methods Full-term neonates with NS born between January 2007 and December 2013 were identified through the Nova Scotia Provincial Perinatal Follow-up Program Database. Perinatal data and neonatal course were reviewed. Neurodevelopmental outcomes were assessed at 18 and 36 months of age using standardized testing. Results Twenty-nine neonates with NS were identified during the study period, giving an incidence of 47 per 100,000 live births in Nova Scotia. Arterial ischemic stroke was the most common stroke type (76%), followed by neonatal hemorrhagic stroke (17%), then cerebral sinovenous thrombosis (7%). The majority of neonates presented with seizures (86%) on the first day of life (76%). At 36 months of age, 23 (79%) of the children had a normal outcome, while 3 (10%) w...
Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques
American Journal of Roentgenology
Pe d i a t r ic I m ag i ng • O r ig i n a l R e s e a rc h This article is available for credit.
Pediatric Neurosurgery
Arachnoid cysts (ACs) are frequently encountered in pediatric neurosurgical practice. Their natur... more Arachnoid cysts (ACs) are frequently encountered in pediatric neurosurgical practice. Their natural history and optimum treatment are not well determined. The authors describe a resolution of asymptomatic middle fossa AC after trivial head trauma in a 7-year-old child. Intracystic bleeding was noticed on interval MRI. Serial MRI follow-up demonstrates stages of resolution of the AC that did not require surgical intervention. Few cases of nonsurgical AC disappearance have been reported, much fewer with trauma as a triggering factor. Here, we present the stages of resolution in images.
Jordan Medical Journal, Jul 22, 2010
Pediatric neurosurgery, Jan 16, 2016
Dysembryoplastic neuroepithelial tumors (DNETs) are generally considered benign, slow-growing epi... more Dysembryoplastic neuroepithelial tumors (DNETs) are generally considered benign, slow-growing epilepsy-associated lesions. While rare cases of malignant transformation of DNET to high-grade glial tumors have been reported, to our knowledge there have been no reports of transformation/emergence of DNET to atypical teratoid rhabdoid tumor (AT/RT), a highly aggressive embryonal brain tumor. Here, we report the case of an 8-year-old boy who presented with an incidental finding of a small right insular lesion which grew slowly over 3 years. The patient first underwent surgery with subtotal tumor resection at age 11. Pathology was consistent with DNET. Following surgery, further tumor growth was evident, requiring fractionated radiotherapy and eventually chemotherapy, but continued tumor growth was witnessed. Three years after radiation, imaging showed dramatic further tumor growth, and the patient underwent a second debulking surgery. The pathology revealed a malignant tumor with BAF47-n...
American Journal of Roentgenology, 2016
The objective of this study was to assess the diagnostic agreement between bowel sonography and M... more The objective of this study was to assess the diagnostic agreement between bowel sonography and MR enterography in children with suspected or confirmed inflammatory bowel disease (IBD). We prospectively studied 33 children undergoing clinically indicated MR enterography. Bowel sonography was performed within 2 hours before MR enterography. The reliability of each modality was assessed by computing the interreader kappa agreement on nine inflammatory markers in eight bowel segments and the interreader intraclass correlation coefficients (ICC) in each bowel segment. The agreement between both modalities in each bowel segment was also calculated using the Kendall coefficient of concordance (KCC) in addition to the sensitivity and specificity of sonography using those of MR enterography as the reference standard. Sonographic readings are substantially reliable in the colon and terminal and distal ileum (ICC = 0.79-0.88) but are highly unreliable in the mid and proximal small bowel. MR enterography has moderate to almost perfect reliability for all bowel segments (ICC = 0.43-0.96). Sonography was in substantial agreement with MR enterography in most of the large bowel (KCC = 0.67-0.83) and terminal and distal ileum (KCC = 0.75) and in moderate agreement in the remaining bowel segments (KCC = 0.45-0.48). Sonographic findings are specific for disease using MR enterography as the reference standard in all bowel segments (0.83-1.00), but sensitivity markedly varies according to disease location. Sonography is highly specific and shows substantial agreement with MR enterography in detecting inflammatory and damage changes in the colon and terminal and distal ileum, the segments most likely to be affected by IBD. Therefore, sonography can be a good complement to MR enterography in evaluations of patients with known or suspected IBD, particularly if MR enterography access is limited.