Basic research helps to understand clinical knowledge which in turn leads to new fundamental research. Two examples are taken from the studies of the anomalies existing in the brain of patients suffering from Parkinson disease or deafferentation Pain. The researches performed to solve these two problems for the past 40 years (in particular by the author's working group) are replaced in the international context. In Man the precision of stereotaxic technique was improved by using the organisation of the somato-sensory thalamic projection described in animals by the physiologists. In the thalamus of Parkinsonian patients, the presence of cells bursting at tremor frequency led to search for the relations existing between the striato-nigral system and the motor thalamus. In the patients suffering from deafferentation Pain, a special role is attributed to the medial thalamus, whose characteristics were formerly studied in animals. The origin of the deafferentation Pain is nowadays studied in an animal model of this disease.

A previously healthy, 21-year-old female presented with acute dermatomyositis. Chest X-ray revealed bilateral hilar adenopathy, and mediastinal lymph node biopsy demonstrated noncaseating granulomata compatible with sarcoidosis. The patient improved spontaneously. The significance of bilateral hilar adenopathy in association with dermatomyositis and implications for management are discussed.

We have had experience with diaphragm pacing in 24 patients at the Toronto Western Hospital. Fourteen patients have undergone bilateral implants to treat chronic ventilatory insufficiency (CVI) caused by traumatic tetraplegia at the C1/2 level (eight patients), neurogenic apnea (five) and one case of neonatal apnea. Unilateral stimulators for nocturnal pacing have been implanted in five patients with central alveolar hypoventilation (sleep apnea) and five patients who suffered CVI resulting from various etiologies. Of the patients who were ventilatory dependent, 80% were successfully weaned and in the entire series, 58% of the patients are living. Diaphragm pacing was successful in 67%, partially successful in 8% and ineffective in 25%. The major complications were: death by pneumonia, failure of the radio receivers, and infection. Diaphragm pacing is the treatment of choice for patients who are ventilator dependent and tetraplegic from upper cervical trauma or in some cases of neurogenic apnea; it may be life saving for patients who suffer central alveolar hypoventilation.

The authors present their experience with intraoperative monitoring of cochlear nerve action potentials (AP) in 30 adult patients. Operative procedures were acoustic neuroma excision with attempted hearing preservation and selective vestibular neurectomy in patients with incapacitating Meniere's disease and serviceable hearing (SRT<50 db, discrimination >60%). Loss of AP is detected rapidly and has been demonstrated after manipulation of the cochlear nerve and after coagulation of small arteries on the tumour capsule. Presence of an AP at the end of the procedure usually correlates with postoperative preservation of hearing. AP monitoring appears to be a reliable means of detecting potentially reversible changes in cochlear nerve function intraoperatively.

Moyamoya disease is an unusual vascular disorder highlighted by progressive bilateral internal carotid artery occlusion and collateralization of intracranial blood flow. Recurrent multifocal cerebral ischemic events and isolated intracerebral hemorrhage are known to occur in this disorder. We report a 52 year old man who over a nine year period had four apparent intracranial hemorrhages. Serial angiograms demonstrated the evolution of moyamoya disease. Pathologic examination confirmed multiple vascular lesions, including two that were clinically silent.

The case histories of two patients with clinically diverse forms of the very rare entity primary, spontaneous mesencephalic hemorrhage are presented. Each exhibited characteristic mesencephalic signs and neuroimaging profiles. However, both patients differed markedly in their predisposing factors, state of arousal, memory, temporal course and functional residua. One patient was unique in displaying a normal level of alertness throughout his clinical course and an isolated retrograde amnesia. The latter sign suggests a role for mesencephalic reticular activation in long-term retrieval and illustrates the differential effects of a subtle activation deficit on memory and arousal. These findings broaden the distinctive clinico-anatomical profile of primary, spontaneous mesencephalic hemorrhage.

Techniques used to monitor the function of the seventh and eighth cranial nerves during acoustic neuroma and other posterior fossa surgery are reviewed. The auditory brainstem response (ABR), electrocochleogram (ECochG) and direct recording from the auditory nerve (CNAP) were compared. The best technique is the ECochG, although in many cases, the CNAP should be used as a back-up technique. The CNAP is especially useful for the identification of the auditory nerve. Both can provide real-time feedback on the physiological integrity of the auditory nerve. The ABR may be helpful in monitoring brainstem function. For some procedures, optimal monitoring requires the combined recording of all three techniques.

Monopolar constant-voltage intracranial stimulation of the facial nerve is helpful for the identification and preservation of the facial nerve. Audio monitoring of spontaneous electromyographic activity provides real-time feedback on the effect of surgical manipulation of the nerve. Monitoring of ephaptic transmission in the facial nerve during microvascular decompression for hemifacial spasm aids in the identification of the offending vessel.

The objectives of the present study were to evaluate the relationship between the fractional amplitudes of the EEG derived from power spectral analysis (PSA) of the electroencephalogram (EEG) and depth of coma measured clinically with the Glasgow Coma Score, and to assess the accuracy of PSA in predicting long-term outcome. Thirty-two patients rendered unconscious by blunt head injury (mean (GCS = 7) had intermittent EEG recordings daily from 1-10 days post injury. There was a significant correlation between fractional amplitude of the EEG and the GCS. The rate and magnitude of change in the EEG and GCS were also correlated. There were significant differences in PSA parameters between improved and deteriorated patient groups at the termination of monitoring (p = .02) and in the change of PSA parameters over time (p = .02). Using linear discriminant analysis of PSA parameters, the accuracy of outcome prognostication based on the six month outcome was approximately 75%. Accurate classification of outcome was possible in a number of patients in whom there was little or no change in the GCS during the period of monitoring.