Biomedical subjects

Cormac O Maher

Publications and source records attributed to Cormac O Maher.

18 recordsLinked to original sources

PubMed2026

Chiari I malformation.

Chiari I malformation (CM1), the most common structural hindbrain disorder in humans, is traditionally characterized by the downward displacement of the cerebellar tonsils through the foramen magnum. However, this definition does not reflect the variability in clinical presentation, natural history and treatment response of this disorder. Some individuals with minimal tonsillar descent have severe neurological symptoms and syringomyelia, whereas others with extensive descent remain asymptomatic. Emerging evidence from neuroimaging, developmental biology and human genetics indicates that CM1 is not a single anatomical entity but a spectrum of disorders resulting from disruptions in coordinated growth and homeostasis across the cerebellum, posterior fossa, craniocervical junction, cerebrospinal fluid and neurovascular systems. CM1 may be best understood as a disorder of disrupted developmental scaling, in which the tightly regulated relationships between cerebellar growth and cranial accommodation are altered within a dynamic neurovascular and cerebrospinal fluid environment. In this context, tonsillar herniation is a geometric consequence rather than the primary disease process. This Primer synthesizes current knowledge on the epidemiology, mechanisms, diagnosis and management of CM1 across the lifespan. We highlight advances in neuroimaging, genomics and phenomics that support a shift from anatomy-based definitions towards an integrated genomic-phenomic classification.

Humans↗

PubMed2006

Pediatric neurosurgery.

Randomized controlled trials of neurosurgical procedures involving children have been organized infrequently; as a consequence, the majority of pediatric neurosurgical practice is not supported by class I data. Furthermore, many trials that have been reported suffer from serious methodological shortcomings such as insufficient power and poor statistical analysis. Finally, several trials of neurosurgical techniques that are frequently performed on children have either excluded children from participation or include an insufficient number of children to draw strong conclusions. Despite these shortcomings, pediatric neurosurgery, like all fields in medicine, is gradually moving towards a more stringent evidence-based medicine standard. This chapter will attempt to summarize the recent progress that has been made in this area.

Clinical Trials as Topic↗

PubMed2006

Lumbar intramedullary spinal schistosomiasis presenting as progressive paraparesis: case report.

OBJECTIVE AND IMPORTANCE: Blood fluke infection or schistosomiasis affects up to 300 million people worldwide. Although infection of the hepatic and urogenital systems commonly occurs, central nervous system involvement is rare. When presenting in the spinal cord, schistosomiasis can be difficult to diagnose because it can present as mass lesion or transverse myelitis. We describe a patient with lumbar intramedullary spinal schistosomiasis who presented to a tertiary medical center in the United States and discuss the diagnosis and treatment of this rare disease. CLINICAL PRESENTATION: A 25-year-old Brazilian man presented with progressive, subacute, bilateral lower extremity motor and sensory deficits and disturbances in bladder function. Magnetic resonance imaging revealed a diffusely enhancing mass expanding the region of the conus medullaris. INTERVENTION: Laboratory investigation disclosed serum and cerebrospinal fluid eosinophilia. Ultimately, cerebrospinal fluid serology demonstrated the presence of Schistosoma mansoni. The patient was treated with praziquantel and steroids and made a marked recovery. CONCLUSION: The clinical and radiographic manifestations of spinal schistosomiasis can mimic those of intra-axial spinal tumors and transverse myelitis. To avoid unnecessary surgery or delay in treatment, the clinician must have knowledge of this type of presentation. The increasing volume of international travel and high prevalence of the disease worldwide increases the possibility that the practicing neurosurgeon in the United States may encounter this rare but treatable disease.

Adult↗

PubMed2006

Very low pressure hydrocephalus. Report of two cases.

Low-pressure hydrocephalus is an extremely rare condition. Authors of the few previous reports on this subject have suggested that symptoms are gradual in onset and successfully treated. In this report the authors presented two unique cases of very low pressure hydrocephalus in which the patients experienced rapid deterioration requiring negative-pressure cerebrospinal fluid drainage to achieve the best possible neurological function; outcomes in both patients ultimately were poor. The constellation of findings suggests that this may be a distinct clinical entity.

Adult↗

PubMed2005

Transorbital penetrating brainstem injury in a child: case report.

The authors present the unusual case of a 9-year-old girl who sustained injury to her brainstem as a result of the orbital penetration of a metal projectile (nail) into the juxtamedullary region. This case and others reported in the literature associate this type of injury with relatively minor complications. Thorough imaging of the intracranial contents and surgical removal of the projectile is recommended.

Brain Stem↗

PubMed2005

Cushing's experience with the surgical treatment of spinal dysraphism.

Although Harvey Cushing is best known for his role in developing surgical treatments for tumors of the central nervous system, he performed diverse neurosurgical procedures throughout his career, both at The Johns Hopkins Hospital (1886--1912) and at the Peter Bent Brigham Hospital (1912--1932). His unique and innovative approach to the treatment of myelomeningoceles associated with hydrocephalus, displayed early in his career, is characteristic of his attempts to circumvent the technical limitations of his time in the management of neurosurgical problems. In this report, the authors discuss the evolution of Cushing's technique in the treatment of myelomeningoceles through two illustrative patient records.

Female↗

PubMed2004

Neurosurgical treatment of brain tumors in children.

Primary brain tumors are the most common solid neoplasms of childhood. The diagnosis of brain tumors in the general pediatric population remains challenging. Nevertheless, it is clear that refinements in imaging, surgical technique, and adjunctive therapies have led to longer survival and an improving quality of life in children with brain tumors.

Brain Neoplasms↗

PubMed2003

Cortical resection for epilepsy in children with linear sebaceous nevus syndrome.

Linear sebaceous nevus syndrome (LSNS) is a rare neurocutaneous syndrome that is associated with seizures and mental retardation. The cortical abnormalities that are associated with this syndrome include focal cortical dysplasia, partial hemimegalencephaly and holohemispheric hemimegalencephaly. Few reports have addressed the utility of cortical resections for epilepsy treatment in the setting of LSNS. We report 3 children with this syndrome who underwent extensive cortical resections and experienced significant improvement in seizure frequency. Our results support the utility of extensive cortical resections for children with this condition.

Cerebral Cortex↗

PubMed2003

Arteriovenous malformation in the trigeminal nerve. Case report.

The authors report on an arteriovenous malformation (AVM) within the trigeminal nerve in an otherwise healthy 76-year-old man who presented with the sudden onset of headache and ataxia. The AVM was totally resected via a lateral suboccipital approach to the cerebellopontine angle. Dural arteriovenous fistulas and AVMs of the dorsal root entry zone and adjacent brainstem that compress the trigeminal nerve have been previously described. To the authors' knowledge, this is the first reported case of an angiographically, surgically, and pathologically proven AVM arising from within the trigeminal nerve itself.

Aged↗

PubMed2003

Interleukin-1beta and adverse effects on cerebral blood flow during long-term global hypoperfusion.

OBJECT: The effects of interleukin (IL)-1beta on the cerebral vasculature are complex and incompletely understood. Many pathophysiological states in which inflammatory cascades have been implicated also have varying degrees of cerebral hypoperfusion. The purpose of this investigation was to examine the long-term effects of this proinflammatory cytokine and its antagonist on cerebral blood flow (CBF) following global cerebral hypoperfusion. METHODS: Sprague-Dawley rats were randomly assigned to 12 groups and given continuous intracerebroventricular (ICV) infusions of IL-1beta, the IL-1 receptor antagonist (IL-1ra), or saline vehicle (control). Global cerebral hypoperfusion was produced by occlusion of both carotid arteries and one vertebral artery. Cerebral blood flow was measured at baseline and again after initiation of the infusions by performing a 133Xe clearance study. Prolonged ICV administration of IL-1beta resulted in a significant decrease in CBF compared with that in controls. Prolonged administration of the antagonist IL-1ra resulted in significant increases in CBF compared with that in both IL-1beta-treated animals and controls. CONCLUSIONS: This experiment demonstrates that long-term treatment with the proinflammatory cytokine IL-1beta adversely affects CBF.

Animals↗

PubMed2003

Evaluation of a novel propylene oxide-treated collagen material as a dural substitute.

OBJECT: The authors evaluated a new non-cross-linked, propylene oxide-treated, acellular collagen matrix for use as a dural substitute in rabbits. They then compared this material to a commonly used dural substitute as well as to native dura mater used during primary closure. METHODS: Forty-six rabbits were randomly assigned to eight groups of five or six rabbits each. These groups differed according to the type of closure material that was used during surgery (native dura, control dural substitute, or experimental dural substitute) and the duration of convalescence. At the end of the experiment, the tightness of the duraplasty was assessed in each live rabbit by continuous infusion of fluid into the cistema magna until leakage was detected. The animals were killed and each specimen was sectioned and studied histologically. The authors found that the experimental dural substitute was safe in animals for this application, that it held sutures well, and that a watertight closure was usually achieved. There were fewer adhesions between the experimental material and neural tissue was less likely to adhere to the cranium than the control graft. Histological examination showed that the experimental material had slightly more spindle cells and vascularity than the control graft. CONCLUSIONS: The experimental graft material has several features that make it an attractive candidate for use as a dural substitute.

Animals↗

PubMed2002

Spontaneous CSF leaks: underlying disorder of connective tissue.

Of 58 consecutive patients with spontaneous CSF leaks, nine exhibited features of connective tissue disorder. One had Marfan's syndrome. Five additional patients had hyperflexible joints, of whom four had arachnodactyly, four were tall and slender, two had hyperextensible skin, and one had a strong family history of abdominal aorta aneurysms. Retinal detachment at a young age was noted in two. One patient had bilateral carotid dissections. A dural weakness may predispose patients to spontaneous CSF leak.

Adult↗

PubMed2002

Frontal lobe epilepsy: diagnosis and surgical treatment.

Frontal lobe epilepsy has been better understood during the past two decades with the advent of technologies with improved localizing capabilities. Major technological advances in the ability to delineate structural and functional brain regions have led to a resurgence of interest in epilepsy surgery. Neuroimaging modalities have broadened the scope of what are now considered surgically remediable syndromes. In the following article, we attempt to review the current concepts regarding diagnosis and surgical management of frontal lobe epilepsy.

Epilepsy, Frontal Lobe↗

PubMed2002

Spontaneous disc space infections in adults.

BACKGROUND: Spontaneous discitis typically affects children; much less is known about the disease in adults. We examined the clinical characteristics and the role of surgery in spontaneous infectious discitis in adults. METHODS: Twenty-nine consecutive adult patients (16 men, 13 women) with spontaneous infectious discitis were treated by a single surgeon (MJE) over a 5-year period. These patients were compared to 19 consecutive patients with postoperative discitis over the same time period. Mean follow-up was 2.4 years. RESULTS: The average age of patients with spontaneous discitis was 69.0 years. Eleven of these patients (38%) were diabetic and 9 (31%) had a known concurrent infection. Infections occurred at cervical (10%), thoracic (34%), and lumbar interspaces (59%), and at multiple disc spaces in eight cases (28%). Ten patients (34%) had an elevated serum leukocyte count and 21 patients (72%) had an elevated erythrocyte sedimentation rate. While Gram-positive infection was most common, a broad spectrum of microbes was isolated. All patients were treated with i.v. antibiotics for a mean duration of 6 weeks. Four patients required surgical fusion; the rest were treated with external immobilization. At follow-up, 21 patients (72%) were symptom-free, 3 patients (10%) had ongoing disease, and 5 patients (17%) had died of unrelated causes. Compared to patients with postoperative discitis treated over the same time period, spontaneous discitis in adults affected older patients and required a broader spectrum of antibiotic coverage. Outcomes were similar between the two groups. CONCLUSIONS: While spontaneous discitis has predominantly been reported in children, the disease also affects older adults. Spontaneous discitis in adults is associated with advanced age, diabetes mellitus, and systemic infection. Elevated serum leukocyte count lacks diagnostic sensitivity. A high cure rate is achieved with antibiotics and external immobilization. Surgical treatment is rarely required.

Aged↗

PubMed2002

Surgical treatment of fibrous dysplasia of the skull in children.

INTRODUCTION: We evaluate the role of surgery in the treatment of fibrous dysplasia of the skull in children. METHODS: We identified 48 consecutive cases of fibrous dysplasia of the skull that were surgically treated at a single institution over a 23-year interval. The 28 patients that initially presented during the first two decades of life were selected for further analysis. Presenting symptoms, signs, surgical treatment, surgical outcome and the state of the disease at the extended follow-up interval were recorded. RESULTS: Fibrous dysplasia of the skull in children most often involved the frontal, sphenoid and ethmoid bones. Most patients presented with facial asymmetry or proptosis. A gross total resection was achieved in 7 patients, subtotal resection in 17 patients, and 4 patients underwent biopsy alone. Over the follow-up interval, 7 patients had symptomatic progression of subtotally resected fibrous dysplasia and 3 patients had asymptomatic progression. The extent of resection was correlated with recurrence risk. CONCLUSIONS: In order to prevent progression of disease, an attempt at gross total resection is indicated in cases of fibrous dysplasia of the skull in childhood where the risk of neurologic morbidity is low and cosmetic results will be acceptable.

Child↗

PubMed2002

Neuromuscular choristoma of the sciatic nerve. Case report.

The authors report the findings of a neuromuscular choristoma of the sciatic nerve in an otherwise healthy 18-year-old man who presented with sensorimotor symptoms and deformities of the right leg and foot. Only a few cases of this rare tumor, also known as "neuromuscular hamartoma" or "benign triton tumor," have been reported in the surgical literature. The authors discuss the clinical presentation, radiological findings, pathological diagnosis, and surgical rationale for this case and review the associated literature.

Adolescent↗

PubMed2002

Intraoperative lidocaine injection into the carotid sinus during endarterectomy.

OBJECT: Many surgeons inject a local anesthetic agent into the carotid sinus before carotid endarterectomy in an attempt to ameliorate perioperative hemodynamic instability. The purpose of this study is to analyze the effect of carotid sinus injection with lidocaine on perioperative hemodynamics and complications. METHODS: The authors prospectively studied 92 patients in whom 100 consecutive carotid endarterectomies were performed by a single surgeon (eight procedures were bilateral). Patients were randomly assigned to one of two groups, in which either 0.5 ml of 1% lidocaine was injected into the carotid sinus nerve or no injection of lidocaine was administered before the arteriotomy. All patients were treated postoperatively according to a standard endarterectomy protocol. There were no significant differences between the two groups in the incidence of hypertension, hypotension, or the use of vasoactive medications in the operating room following restoration of carotid artery (CA) blood flow, in the recovery room, or in the intensive care unit. CONCLUSIONS: Injection of lidocaine into the carotid sinus at the time of endarterectomy is not associated with a significant improvement in any hemodynamic factor, from the time of restoration of CA blood flow to postoperative Day 1.

Aged↗

PubMed2002

Use of cerebrospinal fluid flow rates measured by phase-contrast MR to predict outcome of ventriculoperitoneal shunting for idiopathic normal-pressure hydrocephalus.

OBJECTIVE: To determine whether favorable clinical response and magnitude of improvement are associated with increased aqueductal cerebrospinal fluid (CSF) flow rates in patients who undergo ventriculoperitoneal shunting (VPS) for idiopathic normal-pressure hydrocephalus (NPH). PATIENTS AND METHODS: Between January 1995 and June 2000, 49 patients (14 men and 35 women; mean age, 72.9 years; range, 54-88 years) underwent magnetic resonance quantification of aqueductal CSF flow followed by VPS for presumed idiopathic NPH at the Mayo Clinic, Rochester, Minn. Logistic regression models for the odds of any improvement in score as a function of aqueductal CSF flow and separate models for any improvement in gait, incontinence, cognition, and total score were constructed. RESULTS: Forty-two patients (86%) had improvement in gait at postoperative follow-up (mean, 10 months). Of the 32 patients with incontinence, 27 (69%) improved. Of the 36 patients with cognitive impairment, 16 (44%) improved. In univariate and fully adjusted models, increased CSF flow through the aqueduct was not significantly associated with improvement or the magnitude of improvement in gait, cognition, or incontinence. Thirty-six patients underwent high-volume lumbar puncture preoperatively, of whom 5 (14%) had no response. The aqueductal CSF flow rates of these 5 patients were significantly higher than those of the patients who improved after lumbar puncture. Postoperative complications occurred in 15 patients. The aqueductal CSF flow rates in these 15 patients were not significantly different from those of patients who experienced no complications. CONCLUSION: Among patients who underwent VPS for the treatment of NPH, measurement of CSF flow through the cerebral aqueduct did not reliably predict which patients would improve after shunting or the magnitude of improvement.

Aged↗