Three decades have elapsed since Dawson (1947) recorded the first somatosensory evoked potential (SEP). Simple superimposition of individual responses was possible because the patient had progressive myoclonic epilepsy. In this disease the SEP amplitude is much enhanced (Shibasaki et al, 1978; Kelly et al, 1981). Subsequently Dawson (1951, 1954) presented his averager to the Physiological Society, thereby initiating the present-day explosive growth of evoked potentials.

SEPs are made up of components with varying latencies. The components are best identified by latency and polarity as recorded at the scalp (P = positive and N = negative). Nevertheless, the nomenclature of somatosensory evoked potentials can be extremely confusing, mainly because the same component can have a different polarity depending on the electrode montage used. Generally speaking (but this is not a firm rule), far-field (subcortical) potentials are positive in polarity when a non-cephalic reference is used, whereas these same components have a negative polarity when the reference is on the scalp. It is therefore useful to always indicate the recording montage being employed. In addition, use of absolute latencies in the terminology can cause confusion because they are dependent upon length and body height. For example, the brachial plexus component usually occurs at about 9 msec, but may extend to as long as 11 or more msec in a very tall individual. Subsequent components then become difficult to identify in relation to normal means.

The recent improvements in transsphenoidal microsurgery have once again placed the emphasis on the basophilic adenoma of the pituitary as the etiology of the disease originally described by Harvey Cushing fifty years ago.

In 75 operated cases, tumors were found in 60 cases: 52 were microadenomas, 4 were larger adenomas and 4 were invasive. In 15 cases, no tumor was found at surgery; a selective partial central hypophysectomy was performed in 11 cases and a total hypophysectomy in 4. Among the latter, 3 additional microadenomas were found at pathology. The majority of the microadenomas were located in the center of the gland most often near or within the neural lobe.

In 59 patients with a non invasive tumor, initial cure was obtained in 52 (88%); only 1 of the 4 patients with an invasive tumor was cured.

In the 12 cases without surgical or pathological tumor, partial or total hypophysectomy resulted in 10 cures (83%).

In the brains of patients with senile dementia of the Alzheimer type (SDA T), the quantitatively pathognomonic neuronal lesions (tangles, plaques, granulovacuolar degeneration, Hirano bodies, and nerve cell loss) are predisposed to occur especially within the limbic system. Anatomical and physiological studies indicate that fibres from the trigeminal ganglia innervate meninges and vessels within the middle and anterior cranial fossae, especially in the same subfrontal and mesial temporal regions preferentially afflicted in acute herpes encephalitis. These limbic regions are critical for normal memory processing and recall. Explantation and cocultivation techniques have recently demonstrated Herpes simplex virus in many human trigeminal ganglia, which also reveal a life-long lymphocytic infiltration in the absence of any pathological changes in the sensory neurones. These lymphocytes may represent a histological marker of latent herpes virus, which when reactivating is well-established as the ganglionic source of recurrent herpes labialis. It is suggested that reactivation of the same dormant viral material travelling centripetally instead might be the cause of the “degenerative” lesions typical both of Alzheimer’s Disease and of the normal aged human brain.

An ultrastructural study of the dorsal sympathetic ganglia, chain, and myenteric plexus is described in the streptozotocin diabetic rat after intermittent insulin treatment. The observations described cover the first two weeks following induction of diabetes in which insulin was administered subcutaneously twice daily. Significant regenerative changes were seen with marked axonal sprouting noted at three days. Degenerative changes were seen to be less severe than those in untreated animals. It is concluded that the improvement in the neuropathic changes with insulin treatment supports a transient primary role of the streptozotocin in causing the neuropathy — but that the subsequent improvement seems to be related to the partial control of the diabetes.

Sixty-five children with seizure disorders, who had been treated with multiple anticonvulsants but were poorly controlled, were selected from the Montreal Children’s Hospital Convulsive Disorder Clinic and Neurology Service and were treated with sodium valproate (valproate). All types of seizure disorders were included in the group.

Rapid oral absorption of the drug lead to peak plasma levels in one to three hours (later peaks occurring if administered after meals). A mean plasma half-life of 12.8 hours was calculated. Correlation between oral dose and plasma levels was poor. The side effects which occurred in this study were trivial. Drug interactions occurred with phenobarbital, diphenylhydantoin and clonazepam.

Sixty percent of patients had a greater than 50% reduction in seizure frequency with sodium valproate, but the best response was in generalized absence seizures. Since all types of seizures responded to some degree, a trial of sodium valproate is warranted in intractable seizure disorders of childhood regardless of classification.

In human entrapment neuropathies the characteristic abnormalities in conduction are frequently limited to a short segment of the nerve. Recognition and precise localization of these discrete conduction abnormalities may require measurement of conduction over shorter lengths of the nerves than those lengths commonly employed in the clinical laboratory. Techniques are described for the more precise location of the primary conduction abnormalities in median, ulnar and peroneal nerve entrapments. Distinctive or atypical locations of the major conduction abnormalities may point towards different mechanisms in the pathogenesis of these localized neuropathies.

Anticholinergics are one of the most common treatments used in adult-onset focal dystonias although their general efficacy has not been proven. We have investigated the effects of intravenous administration of atropine, benztropine and chlorpheniramine, in comparison to normal saline, in 20 patients with adult-onset focal dystonias (spasmodic torticollis (9), cranial dystonia (6), writer’s cramp (5)), and have retrospectively reviewed the notes of 78 patients (spasmodic torticollis (38), cranial dystonia (25), writer’s cramp (15)), who had received chronic oral anticholinergic therapy in varying doses at some time in the past. Patients with spasmodic torticollis and writer’s cramp showed no consistent change with any of the intravenous drugs, while the few with cranial dystonia who improved usually did so at the expense of drug-induced sedation. The natural variability of these disorders was evident in the response to normal saline, which caused changes in the scores for severity of the involuntary movements of 20% or more in some patients. Only 8 of the patients who had received chronic oral therapy obtained more than mild benefit, and in 3 of them this improvement was transient. We conclude that cholinergic mechanisms are not of general or prime importance in the pathogenesis of adult-onset focal dystonias. However, each new patient warrants a trial of chronic oral anticholinergic therapy in view of the occasional useful responses obtained with these drugs.

A case of neonatal myasthenia gravis is reported in the infant of an asymptomatic thymectomized mother with comparably elevated acetylcholine receptor (AChR) antibody titers. The mother remained asymptomatic despite elevated antibody titers while the infant became asymptomatic in association with the disappearance of the AChR antibody. It is suggested that the AChR antibody plays an essential role in the development of neonatal myasthenia gravis. It is also suggested that a thymic factor is necessary for the development of clinical symptomatology accounting for the lack of correlation between the clinical state of the mother and infant.

A retrospective review of 253 patients who underwent coronary bypass surgery was performed. Eight (3.2%) had suffered a stroke either intra-operatively (4) or during the early post-operative period (4). A comparison of pre-operative and intra-operative variables between the stroke group and the stroke-free group showed a significant difference only for the hemoglobin level (p < 0.01). All intraoperative strokes occurred in patients who had undergone femoral cannulation; it is suggested that this may have been a source of embolic material in these patients. An embolic origin for most of the strokes (both intra-operative and post-operative) is postulated on the basis of clinical and pathological findings.

Epidural hematomas occasionally have a prolonged clinical course with gradual evolution of the neurologic symptoms. Seven such cases are reviewed in this report. Although the clinical course is insidious, there are certain features which should signal the presence of a slowly expanding hematoma. After an apparently minor head injury, the patient who is usually in the younger age group, develops headache. This persists and is accompanied by other non-specific neurologic symptoms which may lead to a mistaken diagnosis of “post-concussion syndrome”. Papilledema and focal neurologic deficits eventually appear. Definitive diagnosis is made by the CT scan, although contrast enhancement may be necessary to confirm the nature of the lesion. The treatment is craniotomy and evacuation of the hematoma before serious neurologic deterioration occurs.

Cerebral cysticercosis was studied in 89 Mexican children. These patients were divided into two groups; those with proven diagnosis and those in whom the diagnosis was strongly suspected. The frequency of childhood cysticercosis at autopsy is significantly less than reported in adults from the same environment. Symptoms of initial cerebral invasion by the parasite include headache, fever, vomiting, and seizures. Cerebral edema is observed more frequently in children than in adults, and is the most common cause of intracranial hypertension. The cerebral edema generally is associated with an encephalitic syndrome, either a single bout or a chronic course with multiple relapses. Arterial hypertension, not previously described, was found in two probable cases. The variability of clinical symptomatology thus is great. Symptoms in childhood cerebral cysticercosis may be totally absent, moderate, or severe and ultimately fatal. Computed tomography of the brain is the most useful diagnostic aid, and determines the dynamic neuroradiologic sequence of this disease, since different images appear at each stage to permit its diagnosis. Uncalcified cysticerci may be demonstrated by contrast enhancement if associated with focal cerebral edema; images thus may disappear and reappear in the clinical course of the disease.

Three chronic alcoholics developed choreiform dyskinesias involving the face, lips, tongue and, in one case, all limbs; 2 patients for the first time, 9 to 10 days after alcohol withdrawal. These abnormalities improved spontaneously with maintained abstinence from alcohol for 2 to 7 weeks. None had a family history of movement disorder, there was no history of other psychoactive drug use or abuse, and there was no evidence of portal-systemic encephalopathy.

In this series of intracerebral hematomas from aneurysmal rupture, gathered from several neurosurgical services, certain morphological features were studied in detail. Patients with very large hematomas tended to have poor neurological grades on admission to hospital and their immediate discharge outlook was correspondingly poor. Ruptured middle cerebral and pericallosal artery aneurysms were relatively common causes of intracerebral hematomas. Patients with temporal lobe hematoma did relatively well; those with parietal hematoma did poorly. The larger the hematoma the less chance there was of developing cerebral vasospasm but the more likely was pre-operative brain herniation. The survival was more closely linked to size and location of the hematoma than to the location of aneurysm or the degree of midline shift.

A 17-year old female with “malignant” multiple sclerosis died 45 weeks after the onset of the disease. Postmortem examination confirmed the clinical diagnosis of multiple sclerosis. After 30 weeks of rapid clinical progression, the patient was treated with two courses of plasma exchange therapy without immunosuppression. This form of therapy caused a drop in cerebrospinal fluid myelin basic protein levels in one instance, but not in another. Controlled clinical trials are required to determine whether plasma exchange therapy is of value in the management of patients with multiple sclerosis, and the monitoring of cerebrospinal fluid myelin basic protein, if elevated, may be one useful marker to follow as part of these studies.

We studied the flash electroretinograms (ERGs) of 105 patients with multiple sclerosis who were divided into four groups. The first group had no history or clinical evidence of optic nerve dysfunction, the second and third groups had either left or right optic nerve disease respectively, and the fourth group had historical or clinical evidence of bilateral optic nerve disease.

Statistical analysis of the data using analysis of variance (ANOVA) showed that the group of patients with no history or clinical evidence of optic nerve disease had no significant difference from the control group for their peak b-wave implicit times but the other three groups were significantly delayed on the affected side(s). Using the Mann-Whitney U-test we found all four patient groups had significantly greater absolute interocular latency differences from the control group. The electroretinal contribution to flash VEP delay was also investigated. In those patients with unilateral or bilateral optic nerve disease we found that in 14–31% of those patients with flash VEP delay there was also abnormal prolongation of the ERG b-wave. These results confirm a high incidence of retinal dysfunction in multiple sclerosis patients and may suggest that transynaptic degeneration of retinal structures occurs in optic nerve demyelination. The significant absolute interocular latency difference in particular may provide another electrophysiological parameter to establish a diagnosis of multiple sclerosis in suspect cases.