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Biomedical subjects

J M Drake

Publications and source records attributed to J M Drake.

90 records · Page 5Linked to original sources
PubMed1991

Cerebrospinal fluid flow dynamics in children with external ventricular drains.

Fifty-five children had 64 external ventricular drains (EVDs) placed predominantly (95%) for cerebrospinal fluid (CSF) shunt infections. In 9 children, a computer monitoring system measured the CSF output each second continuously for up to 24 hours. The monitoring was repeated daily for up to 9 days. The state of arousal of the patients was recorded simultaneously. In all children, daily EVD outputs were related to age, sex, weight, method of establishing the EVD, height of the drip chamber, time since insertion, and type of infecting organism. Computer monitoring revealed wide fluctuations in flow rate, with peak rates frequently greater than 20 ml/h and periods of flow arrest. These changes were usually associated with increased arousal, but also occurred with sleep. The mean EVD flow rate for all children was 6.3 ml/h. EVD output increased with age and weight. EVD output decreased with Gram-negative or multiple-organism infections and with elevation of the drip chamber. Resolution of the infection, sex of the patient, and method of establishing the EVD had no effect on output. These results predict that CSF production increases with brain growth in humans: that CSF production is depressed by Gram-negative and multiple-organism infections: that implanted CSF shunts with standard valves flow at equivalent rates to an EVD in the supine position; and that the CSF drainage requirements in this group are approximately equal to their EVD outputs.

Adolescent↗
PubMed1991

Computer- and robot-assisted resection of thalamic astrocytomas in children.

Six children ranging in age from 2 to 10 years who harbored deep benign astrocytomas were operated upon using a computer- and robot-assisted system. A radical excision was achieved in all cases with no significant morbidity nor any mortality. The system consists of an interactive, three-dimensional display of computed tomographic image contours and digitized cerebral angiograms taken using the Brown-Roberts-Wells stereotactic frame. The surgical retractor is held and manipulated using a PUMA 200 robot. The position and orientation of the surgical retractor is displayed on the three-dimensional display. Preoperative planning and simulation are important features of this system. Movement of the brain after removal of the tumor and cerebrospinal fluid is substantial, so the tumor removal is based on visually defined margins. Enhanced computer graphics and robotic devices are important adjuncts to neurosurgical procedures and will find increasing use in the future.

Astrocytoma↗
PubMed1991

Intracranial germ-cell tumors in children.

All patients with confirmed intracranial germ-cell tumors treated at the Hospital of Sick Children during the period January, 1952, to December, 1989, were reviewed. Of the 51 tumors reviewed, 16 were located in the suprasellar region, 32 in the pineal region, and three in both the pineal and the suprasellar regions. Forty-nine patients underwent surgical resection which was total in seven and partial in 20, and consisted of a biopsy in 22. Two patients were managed on the basis of serum and cerebrospinal fluid markers. Surgical tools such as the operating microscope, the ultrasonic surgical aspirator, and the laser beam allowed safe debulking and removal of the deep-seated tumors in the pineal region. There were no operative deaths in the 36 patients treated since 1972, who included 23 with pineal tumors. Twenty-five patients with germinomas received radiotherapy and had a 5-year survival rate of 85.1%. Thirteen patients with non-germinoma germ-cell tumors received radiotherapy and had a 5-year survival rate of 45.5%. On the basis of this review, the authors recommend resection of pineal and suprasellar germ-cell tumors in order to firmly establish an accurate histological diagnosis to guide the extent of adjuvant therapy. In the case of a pure germinoma without evidence of dissemination, adjuvant therapy consists only of local radiotherapy. On the other hand, for malignant non-germinoma germ-cell tumors, adjuvant therapy must include chemotherapy as well as craniospinal axis radiotherapy.

Adolescent↗
PubMed1991

Determination of cerebrospinal fluid shunt obstruction with magnetic resonance phase imaging.

The cerebrospinal fluid (CSF) flow rates in 12 patients with symptoms suggestive of CSF shunt obstruction were measured with magnetic resonance (MR) phase imaging. The shunts were imaged over the skull, just distal to any reservoir, using a curved surface coil. Images perpendicular to the direction of flow were made on a 1.5-tesla clinical unit with a flow-sensitive pulse sequence. The patients' ages ranged from 2 months to 28 years. All patients had ancillary investigations to determine the functional status of the shunt. No flow was detected in seven patients with blocked shunts. Flow rates between 3 and 40 cc/hr were found in three patients with functioning shunts. Two patients, one with a blocked shunt and one with a functioning shunt, could not be imaged due to motion artifact. Magnetic resonance phase imaging is a promising technique in the determination of CSF shunt obstruction.

Adolescent↗
PubMed1990

Spinal hemangioblastoma, syrinx, and hydrocephalus in a two-year-old child.

A two-year-old child presented with an acute inability to bear weight. Radiological investigation revealed a large cervicothoracolumbar syrinx of no known cause. During investigation, acute communicating hydrocephalus developed, which required a shunt. At surgery, a small thoracic spinal cord hemangioblastoma was discovered and excised. Complete recovery with collapse of the syrinx followed. The clinical features of this rare childhood tumor and its associated effects are discussed.

Cerebrospinal Fluid Shunts↗
PubMed1989

Magnetic resonance imaging of silastic-induced canine hydrocephalus.

Nine adult beagle dogs underwent magnetic resonance imaging in a 2-Tesla small-bore unit. Six surviving dogs were followed up serially with magnetic resonance imaging after induction of hydrocephalus by injection of Silastic into the prepontine cistern or fourth ventricle. Ventricular size (Y) measured as percentage cross-sectional area of an anterior frontal slice was related to postoperative day (X) as Y = 1.54 + 4.21 x ln(X), r = 0.9596. Periventricular edema appeared initially in the superlateral angles of the frontal horns in an area that corresponded histologically to the subcallosal fasciculus. T1 relaxation time of normal white matter of 979.32 msec increased to 1813.90 msec in the area of the edema (p less than 0.0001). The T2 relaxation time of normal white matter of 83.39 msec increased to 238.26 msec in the area of the edema (p less than 0.0001). Histological changes included expansion of the extracellular space in an area comparable to the region of increased signal intensity on T2-weighted images, as well as diffuse astrocytosis in the chronically hydrocephalic dogs.

Animals↗
PubMed1989

Cerebrospinal fluid shunts: flow measurements with MR imaging.

The authors describe a technique for determination of shunt patency by quantifying cerebrospinal fluid shunt flow rates with magnetic resonance (MR) imaging. This method uses a modified clinical sequence that is both sensitive to slow flow perpendicular to the imaging plane and capable of achieving oblique angles with a 4-cm field of view. Velocity-dependent phase images were used to quantify flow rates within the shunt. A preliminary study was performed in seven patients with hydrocephalus and cerebrospinal fluid shunts. Two patients were found to have zero flow in the shunt, while the remaining five had flow rates ranging from 4 to 19 mL/h. Results showed that the measurement of flow rates within the shunt lumen with MR imaging is clinically feasible.

Adolescent↗
PubMedDate not supplied

Brainstem auditory and visual evoked potentials in infants with myelomeningocele.

Brainstem auditory evoked potentials (BAEPs) and visual evoked potentials (VEPs) were recorded in 47 infants with myelomeningocele to determine if the evoked potentials reflected the early neurological status, and if they had prognostic value as to the children's neurological outcome. The infants were tested between 1 day and 3 months of age (mean 24 days), while still in hospital after the myelomeningocele repair. Outcome was assessed at a mean of 2 years of age. Normal BAEPs were found in 41% and normal VEPs in 62% of the patients. BAEPs were abnormal in all infants studied who had symptomatic Arnold-Chiari (AC) malformation (n = 9); VEPs were abnormal in only 55% of symptomatic infants. Of the infants who did not have symptomatic AC malformation, 53% had normal BAEPs, 69% had normal VEPs. Of the patients with normal BAEPs, 81% had normal cerebral function on follow-up. Of the patients with abnormal BAEPs, 87% had central neurological abnormalities on follow-up. Of the patients with normal VEPs, 63% were normal on follow-up; of the patients with abnormal VEPs, 71% were abnormal on follow-up. Thus, the VEPs studied early in the neonatal course do not appear to be sufficiently sensitive to be valuable prognostically in these infants. However, the BAEPs were consistently abnormal in symptomatic AC malformation and showed a positive predictive value of 88% and an accuracy in predicting central neurological sequelae of 84%.

Arnold-Chiari Malformation↗
PubMedDate not supplied

Intracranial meningiomas in children.

Thirteen cases of intracranial meningioma presenting in childhood were encountered at the Hospital for Sick Children in Toronto over a 51-year period. The clinical features, radiology, operative findings and outcome are reviewed.

Adolescent↗
PubMedDate not supplied

Effect of subcutaneous implantation of anti-siphon devices on CSF shunt function.

Anti-siphon devices (ASD) were initially bench tested at flow rates between 10 and 50 cm3/h and with the distal catheter height between 0 and -60 cm. There was a small increase in pressure with increased flow rate in the horizontal position (p less than 0.001). The inflow pressure initially dropped with the distal catheter height at -20 cm; it then rose progressively with distal catheter heights of -40 and -60 cm (p less than 0.001). To determine the effect of ambient pressure the devices were placed in a barometric chamber at pressures between -200 and +200 mm H2O. Positive pressures caused a linear increase in inflow pressure; negative chamber pressure reduced the anti-siphon effect. Eight ASDs were implanted subcutaneously in piglets and tested in situ weekly for 4 weeks. Implantation caused a mean increase in inflow pressure of 93.5 mm H2O 7 days after implantation (p less than 0.001) and which persisted for 4 weeks. Incision of the capsule surrounding the ASD at the end of 4 weeks caused a drop in pressure. The capsule consisted of an outer layer of collagen fibres with an inner layer of histiocytes. Subcutaneous implantation of ASDs causes an increase in the ambient pressure of the device which significantly increases their resistance to flow.

Animals↗
PubMedDate not supplied

Evaluation, surgical approach and outcome of seizure patients with gangliogliomas.

A retrospective study of 15 children with intracranial gangliogliomas and intractable seizures revealed that tumors associated with seizure were located in the temporal and frontal lobes. These patients underwent lobectomy under electrocorticography. Mesial temporal sclerosis was identified in the hippocampus of the excised temporal lobe in 7 of 13 patients with temporal lobectomies. Eleven of the 15 children were seizure-free over a mean follow-up period of 4 years. The surgical approach to gangliogliomas requires careful pre-operative evaluation, including neuroimaging and electrophysiological study to locate seizure activity. Removal of epileptogenic brain as well as the ganglioglioma is recommended to optimize seizure control.

Adolescent↗
PubMedDate not supplied

Complications of cerebrospinal fluid shunt antisiphon devices.

The case histories of 38 children with implanted antisiphon devices (ASD) were retrospectively reviewed. Sixty-three percent suffered a shunt malfunction within 5 years of ASD implantation. The probability of shunt malfunction within 1 year was of 40%. Patients with myelomeningocele experienced the highest rate of malfunction. Age, order of ASD implantation (whether implanted primarily or secondarily), shunt pressure, and reason for ASD insertion did not significantly alter the incidence of malfunction. Fifty percent of the shunt complications were specifically related to ASD malfunction. Functional obstruction of the shunt system as determined by evidence of clinical shunt obstruction with documented patency on shunt flow testing occurred in 10 of 38 patients. No variable studied could be significantly related to the probability of developing an ASD-related complication. Functional obstruction of the ASD is a common and unpredictable complication of these devices.

Adolescent↗
PubMedDate not supplied

Hydrocephalus in Apert syndrome: a retrospective review.

A retrospective evaluation was carried out to define the incidence of hydrocephalus and associated factors in 44 patients with Apert syndrome treated at The Hospital for Sick Children in Toronto over a 22-year period. Forty-three of these patients underwent cranioorbital decompressive procedures within 1 year of birth. Fifteen of 25 (60%) patients who had either a computed tomography scan or pneumoencephalogram had ventriculomegaly, and 3 of the 25 (12%) had associated brain anomalies. Ten of the 44 (23%) patients had cerebrospinal fluid (CSF) shunts placed, 7 lumboperitoneal and 3 ventriculoperitoneal. Six of the shunts were placed early after cranioorbital procedures (CSF leaks in 5 cases and a subgaleal fluid collection in 1 case). The average IQ of 15 patients evaluated by the Wechsler Intelligence Scale was 72.5, indicative of significant intellectual impairment. There was no correlation between IQ and ventricular size. Although hydrocephalus characterized by progressive ventricular dilatation is uncommon in Apert syndrome, postoperative problems related to impaired CSF circulation are common and may indicate an underlying CSF absorptive deficit.

Acrocephalosyndactylia↗
PubMedDate not supplied

Optic pathway/hypothalamic gliomas: a dilemma in management.

Optic pathway gliomas follow an unpredictable course. Some remain static for years; others increase rapidly in size and often lead to death. This unpredictability, along with the histological similarity of these tumors, has resulted in controversy about their management. We have reviewed the results of management of all 62 patients with a diagnosis of optic pathway/hypothalamic glioma treated at The Hospital for Sick Children during the years 1976-1990. Twelve patients received no direct treatment, and 3 only a biopsy. Six patients were treated with radiotherapy alone. Eight patients received radiotherapy following a biopsy. Seventeen patients were treated by resection alone and 16 had a resection followed by radiotherapy. Eight patients received chemotherapy in addition to other therapy, and in 5 of them the chemotherapy was given as an initial therapy. Forty-eight patients are well with their visual deficits but 7 of them are receiving hormone replacement therapy. Six patients have significant neurologic deficits and 8 have died.

Brain Neoplasms↗
PubMedDate not supplied

Childhood fibrous dysplasia presenting as blindness: a skull base approach for resection and immediate reconstruction.

Fibrous dysplasia is an abnormal fibroosseous process of bone of unknown cause. The incidence of skull involvement varies, painless enlargement being the most common presenting symptom. Change in vision is a rare but recognized finding. We report a 3-year-old boy with extreme fibrous dysplasia involving the skull base, who presented with blindness. He underwent exposure osteotomies of the frontal bones and orbits to provide access for skull base tumor removal. The orbital roofs were reconstructed with microplate-fixed cranial grafts. One and one half years after tumor excision followed by immediate reconstruction, the boy retains facial symmetry, and his ocular function has not deteriorated.

Blindness↗
PubMedDate not supplied

Fatal ethibloc embolization of vertebrobasilar system following percutaneous injection into aneurysmal bone cyst of the second cervical vertebra.

A 4-year-old boy developed progressive neck pain and an expansile osteogenic lesion of C2; the diagnosis was an aneurysmal bone cyst. An image-guided biopsy with 3D CT planning was performed followed by Ethibloc injection into the aneurysmal bone cyst. Subsequent CT and MR images demonstrated embolization material in the vertebrobasilar system, and the patient died of brain stem and cerebellar infarction 23 hours after the intervention. The course of events and technical considerations are discussed.

Basilar Artery↗