David W. Rowed

The University of Toronto Head Injury Treatment Study : A prospective, randomized comparison of pentobarbital and mannitol

Fifty-nine patients were treated in a prospective, randomized comparison of pentobarbital and mannitol for the control of intracranial hypertension resulting from head injury. Patients with elevated intracranial pressure (ICP) after evacuation of intracranial hematomas were randomized to one of two treatment groups; mannitol initially or pentobarbital initially, followed by the second drug as required by further elevation of ICP. Similarly, patients with raised ICP but without hematomas requiring evacuation were randomly assigned to two treatment groups in an identical paradigm. Those with ICP elevation and no hematoma treated with pentobarbital as initial therapy had a 77% mortality compared to a 41% mortality for those with mannitol as initial treatment. Patients with evacuated hematomas had mortalities of 40% and 43% (no significant difference) for pentobarbital and mannitol respectively. In both no-hematoma and hematoma streams pentobarbital was less effective than mannitol for control of raised ICP. Multivariable statistical analysis indicates that pentobarbital coma is not better than mannitol for the treatment of intracranial hypertension and may be harmful in no-hematoma patients with intracranial hypertension after head injury.

Recurrent Intracranial Hemorrhage Due to Postpartum Cerebral Angiopathy Implications for Management

BACKGROUND Postpartum cerebral angiopathy as a cause of hemorrhagic stroke in young women is not well recognized. It is unknown whether this disorder represents a true inflammatory vasculitis or transient vasoconstriction related to the hormonal events of pregnancy and the postpartum period. CASE DESCRIPTION A 39-year-old woman presented with postpartum intracranial hemorrhage and, 32 months later, with subarachnoid hemorrhage, following normal pregnancies. Cerebral angiography obtained after each stroke demonstrated diffuse irregularity of branches of the middle cerebral arteries consistent with a diffuse vasospastic process or classic vasculitis. Neurological deficits resolved and results of a transcranial Doppler study normalized after a short course of high-dose corticosteroids following the second stroke. CONCLUSIONS Postpartum cerebral angiopathy should be considered in the differential diagnosis of recurrent intracranial hemorrhagic stroke in young women. Recognition of this condition may preclude treatment with potentially toxic therapies for vasculitis and will have important implications for counseling women on subsequent pregnancies.

Cerebrospinal fluid leaks and meningitis in acoustic neuroma surgery

Cerebrospinal fluid leaks and associated meningitis are the most common life-threatening complications of surgery for acoustic neuromas. This retrospective study reviews 319 patients who had surgery for 321 acoustic tumors at the Sunnybrook Health Sciences Center, University of Toronto, from April 1975 to March 1990. Cerebrospinal fluid leaks occurred after 13.4% of primary tumor operations. Surgical repair was required in 6.2% of all patients; 4.4% needed more than one operation. Meningitis occurred in 5.3% of all patients. These complications were more common in larger tumors and after the combined translabyrinthine middle fossa approach. Transnasopharyngeal eustachian tube obliteration was used to stop recurrent cerebrospinal fluid leaks in two patients.

Pain after surgery for acoustic neuroma.

Postoperative pain after surgery in the cerebellopontine angle (CPA) is acknowledged to occur, but is rarely taken into account as a factor in the analysis of morbidity of such surgery. It is widely acknowledged that some patients, having undergone such surgery, particularly by means of the suboccipital approach, report significant postoperative pain and headache. This study was undertaken to determine the incidence and severity of pain after excision of acoustic neuromas and to establish whether this differed between the suboccipital and translabyrinthine routes. Ninety-one percent of all patients (n = 58), who had the suboccipital approach used for removal of their tumor, were surveyed. A smaller group (n = 40), MAtched for tumor size, age, and sex, but in whom the translabyrinthine approach was used, was similarly studied. A standard questionnaire, designed to detect and quantify postoperative pain, was administered to each patient. Of patients who underwent tumor excision by means of the suboccipital approach, 63.7% experienced significant local discomfort and headache, whereas this was notably absent in all those who had undergone translabyrinthine excision. In view of the significant morbidity noted to follow the suboccipital approach, several modifications of the surgical technique used were devised.

Cervical Myelopathy Caused by Hypoplasia of the Atlas: Two Case Reports and Review of the Literature

OBJECTIVE AND IMPORTANCE Congenital anomalies of the posterior arch of the atlas (C1) are uncommon. They range from partial clefts to total agenesis of the posterior arch. Developmental cervical canal stenosis is a congenital anomaly that may cause cervical myelopathy. Myelopathy caused by cervical stenosis at the level of the atlas has been reported in only three cases. We present two cases of nontraumatic cervical myelopathy caused by spinal stenosis at the level of the atlas associated with a hypoplastic but complete posterior arch of C1. CLINICAL PRESENTATION Two elderly Chinese men developed cervical myelopathy gradually during months to years, without preceding trauma. Imaging revealed a hypoplastic but complete posterior C1 arch associated with changes of spondylosis in both patients, producing severe spinal stenosis and spinal cord compression. Posterior decompression was achieved in both by the removal of the posterior arch of C1 with its surrounding thickened posterior ligaments. Symptoms and clinical findings improved in the two patients during the follow-up period. CONCLUSION The anomaly presented in our two cases differs from the established classification of congenital abnormalities of the posterior arch of the atlas, suggesting a different embryological defect. The hypoplastic posterior C1 arch created a congenitally narrowed spinal canal in our patients, rendering the spinal cord more susceptible to compression related to degenerative changes of the spine. Surgical removal of the shortened posterior C1 arch and surrounding degenerative ligaments is an effective treatment for symptomatic patients with this condition.

Cavernous Malformation Presenting As an Extra-axial Cerebellopontine Angle Mass: Case Report

OBJECTIVE AND IMPORTANCE We describe a rare case of an extra-axial cavernoma of the cerebellopontine angle without internal auditory canal involvement and with an unusual appearance on preoperative magnetic resonance imaging (MRI). Only three cases of cerebellopontine angle cavernomas have been previously reported, and none of these reports included preoperative MRI. CLINICAL PRESENTATION A young man presented with subacute left facial hypesthesia and chronic asymmetrical sensorineural hearing loss. MRI revealed a mass, which was isointense on T1- and T2-weighted images, with evidence of hemorrhage (methemoglobin and hemosiderin). The lesion did not enhance after the injection of gadolinium. INTERVENTION The lesion was removed without difficulty by a suboccipital approach, with intraoperative electrophysiological monitoring of facial and cochlear nerves. Facial paresis cleared postoperatively. CONCLUSION The present case suggests that the appearance of cerebelopontine angle cavernomas as revealed by MRI may be similar to that of intraparenchymal cavernomas. This is in contrast to previously reported cases of extra-axial cavernomas at other sites. Evidence of hemorrhage in an extra-axial lesion revealed by MRI suggests a possible diagnosis of cavernoma.

Acoustic neuroma surgery: the results of long-term hearing preservation.

Objective To report the long-term outcome hearing results following acoustic neuroma surgery. To determine whether changes, if any, in the thresholds of the operated ear are mirrored in the contralateral unoperated side. In addition, to identify predictive factors, if any, that may predispose individuals to hearing loss in the operated ear in the late post-operative period. Study Design Retrospective patient chart review Setting University Tertiary Referral Centre Patients From 1978 to 1997, one hundred and twenty six patients with small acoustic neuromas (less than 2cm as measured within in the cerebellopontine angle) underwent excision via the suboccipital (retrosigmoid) approach with the patient in the prone position. Hearing preservation was successful in 43 patients (34.1%). The audiometric data of thirty patients with a minimum follow-up interval of 36 months was analyzed. The mean follow-up period was 113.4 months (range 36-264, SD=57.8) and the mean age at surgery was 47.3 years (range 32 to 64, SD = 7.3). Outcome Measures Speech Reception Thresholds (SRT), Speech Discrimination Scores (SDS) and Pure-tone Audiometry (PTA, 0.5, 1 & 2 kHz) were noted on the operated and unoperated ears. The AAO Classification according to the Committee on Hearing and Equilibrium guidelines for the evaluation of hearing preservation in acoustic neuroma was used to assess hearing serviceability. Results Subsequent to including corresponding changes in the unoperated ear, the means of the SRT and PTA in the operated ear between the early and late post-operative periods were statistically significantly different (p=0.0012 & 0.034 respectively). Twelve (40%) patients demonstrated significant deterioration in hearing thresholds over time. Pre-operatively, 96.7% of patients had serviceable hearing (Class A & B). This falls to 76.6% in the early post-operative period and to 56.7% in the late post-operative period. Conclusion Our study highlights the finding that over time a significant number of individuals realize a greater ongoing hearing loss in the post tumour excision ear than the contralateral ear.

Chronic Cluster Headache Managed by Nervus Intermedius Section

SYNOPSIS

Severe tension pneumocephalus complicating frontal sinus osteoma.

BACKGROUND Tension pneumocephalus, the accumulation of intracranial gas under pressure, is a rare but potentially life-threatening condition which can complicate craniofacial surgery, trauma, or cranial tumor. It presents as an acute or subacute expanding mass lesion. CASE REPORT We present a case of a 40-year-old male who developed tension pneumocephalus as a consequence of a previously detected but untreated frontal sinus osteoma. Despite prompt decompression and repair of the fistulous connection between the sinus and the intracranial compartment, the patient suffered permanent frontal lobe damage with significant neurocognitive sequelae and seizures. CONCLUSIONS This case illustrates that tension pneumocephalus can be a dangerous entity with potential for early mortality and long-term morbidity. We recommend, therefore, early treatment and close follow up of destructive lesions involving the posterior frontal sinus wall.

A novel method in predicting immediate postoperative facial nerve function post acoustic neuroma excision.

Abstract: To determine whether the percentage calculated by dividing the amplitude of postexcision direct facial nerve stimulus responses (at pontomedullary junction) by the amplitude of distal ipsilateral transcutaneous (stylomastoid region) maximal stimulus responses and response amplitude progression by increasing stimulus intensities have predictive value for determining normal or near-normal (House-Brackmann Grade 1 or 2) immediate postoperative facial nerve function. Study Design: Intraoperative recordings of three muscle groups: 1) frontalis, 2) orbicularis oculi, and 3) orbicularis oris. Postexcision direct facial nerve stimulation at the pontomedullary junction and transcutaneous maximal facial nerve stimulation at the ipsilateral stylomastoid region and their associated response amplitudes were recorded. Setting: Tertiary referral center. Patients and Methods: Patients who underwent acoustic neuroma surgery from January 2004 to March 2006 with intraoperative facial nerve monitoring and an intact facial nerve after tumor excision were included. Recordings were available for 38 patients. Results: With a stimulus intensity of 0.3 mA at the root exit zone, there was an 81% positive predictive value in patients that exhibited a compound action potential of greater than 20% of maximum (sensitivity, 81%). This increased to 93% when the compound action potential was greater than 50% of maximum. When the amplitude increase was greater than 5 &mgr;V, there was a 77% positive predictive value (sensitivity, 87%). Conclusion: The percentage of the response amplitude of direct facial nerve stimulation at the pontomedullary junction when compared with the maximum response amplitude of ipsilateral transcutaneous stimulation at the stylomastoid foramen is a good predictor of normal to near-normal immediate postoperative facial nerve function. Progression of amplitude response also seems to be a good predictor of normal to near-normal immediate postoperative facial nerve function.