The aspects of trigemina! sensory structure and function which are uniquely different from spinal systems are reviewed in this paper.

In the periphery, several unique arrangements of sensory receptors are seen, and appear to have unique sensory functions. The receptors in the cornea, the nasal mucosa, and the tooth pulp are morphologically unspecialized and are associated with “protopathic” sensory experiences. The important sensory functions of the mammalian vibrissae are also discussed, as well as their relationship to the anatomically distinctive cortical “barrels”.

Aspects of trigeminal proprioception are also of interest. The absence of spindles in some muscles and the unique central organization of trigeminal proprioceptive afférents in the jaw and extraocular muscles are of functional significance in the motor function of the jaw and the eye.

Trigeminal afférents are also involved in several complex autonomie reflexes. Characteristic changes in cardiovascular and respiratory function are elicited by various patterns of trigeminal sensory stimulation. These reflexes include the diving reflex, the oculo-cardiac reflex, naso-cardiorespira-tory reflexes, and the trigeminal depressor response. The clinical significance of these reflexes is discussed.

Several coordinated behavioral responses including suckling are also elicited from trigeminal afférents. The evidence implicating trigeminal afférents in eating and drinking behavior is presented.

Sixteen patients with narcolepsy and cataplexy were treated with gamma-hydroxybutyrate (GHB) given at night and tailored to achieve as continuous a night's sleep as possible. The dosage usually consisted of 1.5-2.25 gm orally at bedtime and then one or two further 1.0-1.5 gm doses with awakenings during the night, and totaled about 50 mg /kg. Apart from one patient who took only the bedtime dose, the subjective quality of night sleep improved in all patients and the number of irresistable daytime attacks of sleep and cataplexy substantially diminished. Some residual daytime drowsiness remained and this usually responded well to low doses of methylphenidate. Improvement has been maintained for up to 20 months without the development of tolerance. Two patients experienced adverse side effects necessitating withdrawal of GHB treatment, but no serious toxic effects have occurred.

Thirty cases of spinal epidural abscess are reviewed with particular emphasis on mode of presentation and results of treatment. In spite of repeated exhortations in the literature for earlier diagnosis, the results remain unsatisfactory because many patients have progressed to severe or complete paralysis before the correct diagnosis is made and surgical treatment carried out.

Effects of chronic denervation upon in vivo forearm metabolism were studied in six patients and six controls. The diagnosis was amyotrophic lateral sclerosis in four patients, the neuronal form of Charcot-Marie Tooth disease in one patient, and an unclassified chronic disease of the lower motor neurons in one patient. In all cases the forearm muscles showed clinical weakness and electrical evidence of denervation, while muscle biopsy from a proximal muscle of the upper limb showed typical denervation atrophy. At rest there was increased oxygen utilization and lactate output as well as a tendency for increased uptake of glucose and long chain fatty acids from arterial blood per 100 ml of f orear m tissue. During exercise the abnormally high lactate output increased further. An increased arterial lactate concentration was present during rest and exercise. Oxidation of fatty acids was not impaired. It is suggested that these abnormalities are consistent with an augmented utilization of blood borne fuels at rest by denervated muscles. A concurrent regional ischemia of muscles during rest and exercise, possibly due to defective autoregulation of skeletal muscle blood flow, may exlain the abnormally high lactate generation.

One hundred and eleven cases of syncope or loss of consciousness are analyzed. Most are of obscure nature while some illustrate features of syncope that deserve further scrutiny. The cases are divided into six groups: 1) Resembling cardiac syncope (30 cases); 2) vasovagal syncope (22 cases); 3) features of both cardiac and vasovagal syncope (12 cases); 4) orthostatic hypotensive (29 cases); 5) akinetic seizure? (12 cases); and 6) miscellaneous (5 cases). Some groups are subdivided according to the circumstances surrounding the spells, for example, seated eating, nocturnal, associated with bowel movement, response to anticonvulsant therapy, etc. The following conclusions seem warranted: 1) The evidence favors the existence of a type of akinetic seizure resembling cardiac syncope; 2) loss of consciousness while seated eating (prandial syncope) may comprise a syndrome; 3) syncope related to bowel movement or abdominal pain is a striking association; 4)sporadic nocturnal syncope due to temporary hyp or e activity ofbaroreceptors is not sufficiently recognized; 5) alcohol ingestion may precipitate orthostatic hy-poreactivity of baroreceptors is not sufficiently recognized; 5) alcohol ingestion may precipitate orthostatic hypotension. Familial syncope, syncope proneness and cold drink syncope are illustrated.

Four hundred and ninetytwo ulnar nerves were studied in 237 patients with cubital tunnel syndrome and 233 subjects without clinically apparent ulnar neuropathy. Terminal motor and sensory latencies, motor and sensory conduction velocities, sensory action potential amplitudes and dispersions, and needle electromyography were analysed by a 0 to 10 rating — the EMG score. The patients were clinically graded from 1 (least severe) to 4 (most severe). The median EMG scores of these were 0.9/10 (N=70): 1.6/10 (N=81); 4.7/10 (N=46); and 7.1/10 (N=56), respectively. The median EMG score for the controls was 0.6/10 (N=239) and 14.7% had asymptomatic ulnar entrapments. This incidence reached 30% in controls who were 60years or older. In 25 other controls, the above sulcus sensory action potential was analysed. Its mean dispersion was 4.9 ± 1.0 s-3. This measurement was significantly prolonged in 84.6% of 13 studies in which the EMG score was 0/10. These patients had either sensory symptoms only or an additional mild sensory deficit. Comparison of the EMG score obtained with sequential studies would allow one to objectively evaluate improvement or deterioration of the clinical state, giving a rational means of determining the need for surgery.

Unilateral lesions involving the area immediately caudal to the locus coeruleus in the cat are associated with slight decreases of noradrenaline (NA) in both sides of the spinal cord without any important change of serotonin (5-HT) concentration in the spinal cord and of N A and 5-HT concentrations in the cerebral cortex of both sides. In other cats with similar lesions involving the same area bilaterally (postlocus lesions) NA is markedly decreased and 5-H T slightly decreased in the hypothalamus and spinal cord but the concentrations of NA and 5-HT of the cerebral cortex, striât urn and thalamus are not conspicuously modified by such postlocus lesions.

Unilateral lesions in the area of the loci coeruleus and subcoeruleus in the rat are associated with a marked decrease of noradrenaline (NA) in the ipsilateral cerebral cortex without any important change of NA in the contralateral cortex and in the spinal cord of both sides. Under such conditions the concentrations of serotonin (5-HT) are not significantly modified in the cerebral cortex and spinal cord of both sides. NA and 5-HT concentrations of the cerebral cortex of both sides are unmodified by unilateral lesions of the cerebellar nuclei in the rat. In the latter group of animals slight increases of NA and 5-HT in the spinal cord are significant in comparison to the values obtained in the control animals but not from one side of the spinal cord to the other.

These results further support the suggestion that the noradrenergic coeruleo-cortical pathway originating in the loci coeruleus and subcoeruleus ascends on the same side and ends in the ipsilateral cerebral cortex. In the light of the results of this investigation and of those reported in a companion paper (Marchand et ai, 1979) NA fibers reaching the hypothalamus and spinal cord most likely arise from neurons located caudally in respect to the locus coeruleus. Moreover NA fibers ending in the hypothalamus do not ascend in the dorsolateral part of the isthmic area and, therefore, have a different course than the N A fibers reaching the cerebral cortex and thalamus.

Fifteen regional cerebral blood flow studies (rCBF) were conducted on 14 patients with arteriovenous malformations (AVM). Only one patient was studied at the time of a hemorrhage. None of the patients were operated upon. All patients had angiographically demonstrated lesions. All the CT scans performed demonstrated the lesions. rCBF was increased in the involved hemisphere compared to the non-involved hemisphere and the difference was greater when the malformations were superficial. There was a higher incidence of high flow regions in the involved hemisphere of patients with AVMs compared to our normal control group and patients with subarachnoid hemorrhage (SAH) from aneurysms. Flow rales within the involved hemisphere demonstrated abnormal distributions and greater variability than normals. Some peaks previously demonstrated in the intraarterial flow studies are not apparent using the inhalation method. This noninvasive technique has a potential to provide additional useful information on the natural history of this disorder.

Thirty-nine epileptic patients underwent pulmonary function testing. Twenty-one of these patients, ranging in age from 16 to 44 years, had taken diphenylhydantoin (DPH) for 2 to 17 years. Eighteen patients, who had taken other anticonvulsants for similar time periods served as controls. Five patients in the DPH group had lung volume abnormalities, four had abnormal airway function, and five had abnormalities of alveolar gas mixing. One patient in the control group had lung volume abnormalities, two had abnormal airway function, and five had abnormalities of alveolar gas mixing. Statistical analysis revealed no significant differences between the groups, or between either group and predicted values.

Between 1964 and 1976, we have seen 197 cases of cerebral tumors in children. We have studied the frequency of each histological group of tumors, their localization, the results of the clinical investigation, their clinical manifestations and the prognosis for each group.

This study has confirmed that in children brain tumors are more frequently localized in the posterior fossa (56.4%). As in other series, tumors derived from the glia represent nearly 80% of the total. Clinically, increased intra-cranial pressure is the most frequent manifestation of posterior fossa lesion (75% of cases) while cerebellar involvement was seen in 60% of these childdren. Brain stem lesions and supratentorial tumors are more insidious in their presentation and their clinical manifestations more diversified.

The EEG appeared useful in the investigation of brain tumors and showed irregularities in 78% of our patients. However, a more specific diagnosis required more invasive techniques such as angiography, pneumoencephalography or ventriculography.

As in previous series, the mortality rate remained high in the children we have followed, particularly for some groups of tumors (glioblastoma, medulloblastoma, brain stem lesions). It is to be hoped that with the introduction of the CT Scan, the improvement of neurosurgical techniques and the use of immuno and chemotherapy, the prognosis may be improved.

Because there is biochemical evidence of decreased GABAergic function in Parkinson's disease, sodium valproate, an inhibitor of GA BA catabolism, was administered to eight Parkinsonian patients. Valproate treatment did not significantly alter any Parkinsonian feature, but tended to increase the dyskinesia in the “on-off” patients. The increased dyskinesias were not a result of altered peripheral metabolism of L-dopa. Despite obtaining high plasma levels of valproate, no consistent alteration of CSF GABA levels could be demonstrated. Thus, in these patients, an effect of valproate on GABA metabolism is unproven, and in turn, the role of GABA in Parkinsonism and dyskinesia uncertain.

Unilateral lesions in the area of the loci coeruleus and subcoeruleus in the cat are associated with a significant and sustained decrease of noradrenaline (NA) in the ipsilateral cerebral cortex without any important change in the concentrations of NA in the contralateral cortex and in the spinal cord of both sides. The serotonin (5-HT) concentrations of the spinal cord and cerebral cortex of both sides remained unchanged in the same groups of animals. Bilateral lesions in the same area result also in a marked decrease of NA in the cerebral cortex of both sides. The latter lesions also result in slight decreases of NA in the hypothalamus and of NA and 5-HT in the spinal cord but the NA and 5-HT concentrations of the stria-turn and thalamus and the 5-H T concentrations of the cerebral cortex and hypothalamus are unmodified by such lesions. Unilateral lesions of the area immediately rostral to the locus coeruleus (praelocus lesions) result in a very significant decrease of NA in the ipsilateral cerebral cortex without any change of NA in the contralateral cerebral cortex and spinal cord of both sides. Similar lesions produced bilaterally in another group of cats resulted in marked decreases of NA in the cerebral cortex of both sides and a slight decrease of NA in the thalamus without any change of NA in the striatum, hypothalamus and spinal cord and of 5-HT in the cerebral cortex. In the same group of animals with lesions which, however, extended more closely to the midline than in cats with locus coeruleus lesions, 5-HT is markedly decreased in the striatum and thalamus and slightly decreased in the hypothalamus and spinal cord.

These results support the view that the noradrenergie coeruleo-cortical pathway is made up of fibers which originate in the loci coeruleus and subcoeruleus and pre-dominently end ipsilaterally to their origin in the cerebral cortex. Ascending NA fibers ending in the thalamus appear to originate from NA neurons located more laterally in the upper pons and more specifically at the level of the parabrachial nuclei.

A case of progressive multi-focal leukoencephalopathy (PML) with selective involvement of cerebellum and brain stem is compared with nine other published cases. Recognition of PML presenting with ataxia before cerebral manifestations is stressed especially, since promising results with some antiviral drugs have been claimed.

A World Health Organization Expert Committee has concluded that symptoms of methylmercury poisoning may appear at blood concentrations of 200-500 ng Hg/ml. Blood levels in this range have been found in several Indian and Inuit communities in Canada. The syndrome of severe methylmercury poisoning (Hunter-Russell syndrome) is well described. However, diagnosis of less severe cases is difficult. This paper reviews the present situation in Canada. The problems of diagnosis currently being encountered are discussed and are illustrated by the case of an individual who had one of the highest blood concentrations (551 ng Hg/ml) ever described in fish-eating populations outside of the outbreaks in Minamata and Niigata in Japan. Although mercury concentrations in brain were estimated to have been in the “symptomatic” range at least once in the two years prior to his death, neurohisiological examination was normal. Detailed examination by two teams of neurologists revealed effects that may be associated with methylmercury poisoning but a definitive diagnosis remained elusive.

Valproic acid in therapeutic doses was used in the treatment of postanoxic intention myoclonus. Disappearance of the myoclonus occurred with marked improvement in the electroencephalogram. No significant side effects were noted. Hepatic function tests were monitored. Determination of valproic acid plasma levels was used to guide therapy. Levels above 55 ßg were generally required. The patient remains free of myoclonus after four and one half months.

The management of the pregnant epileptic requires close cooperation between the neurologist and obstetrician. To prevent complications, knowledge is required about the natural history of epilepsy during pregnancy, the possible teratogenic effects of antiepileptic drugs, and changes in their absorption, biotransformation, and excretion. Close plasma antiepileptic drug monitoring is required because of the change in the handling of antiepileptic drugs during pregnancy. The treatment of status epilepticus with intravenous phenytoin is effective. Drug interactions which may lead to toxic plasma levels of some drugs and subtherapeutic plasma levels of others should be anticipated. The risk of problems resulting from antiepileptic drug therapy during pregnancy appears to be minor, provided that proper medical supervision is available. Newer antiepileptic drugs should not be administered to the pregnant epileptic until their safety in pregnancy is fully established.

Significant susceptibility to photically induced seizures has in the past been observed only in Senegalese baboons (Papio papio) and epileptic humans. However, we have unexpectedly observed a phot omy oclonic response to intermittent photic stimulation in 5 of a sample of 6 yellow baboons (Papio cynocephalus).

Brain edema (BE) research lacks quantitative regional methods. We modified the method of Pappius and McCann (1969), who used radioactive iodinated I125 serum albumin (RISA) as a label for vasogenic BE fluid. To correct for intravascular plasma volume we used Cr51 labelled red blood cells and calculated equivalent extravascular plasma volume (EVPV). The modified RISA method was compared with a standard method for measuring increased tissue water, i.e. the change in wef.dry weights. Anesthetized rabbits were subjected to unilateral cortical freeze injury and sacrificed three hours later. The lesion corresponding to the area of blood brain barrier (BBB) breakdown was delineated by Evan's blue staining. That area and the two adjacent poles were sectioned. The contralateral hemisphere was used as the control. Good agreement was found between the two methods. By the modified RISA method, 4.08% of the wet weight of the injured hemisphere was EVPV while the decrease in dry weight corresponded to 5.56% edema. In the freeze lesion, however, where BBB breakdown occurred extravascular (EV)protein exceeded EV water, while adjacent to the lesion in the area with intact BBB, EV water exceeded EV protein. This suggests that the diffusion rate for water through brain tissue exceeds that of albumin in the early stages of vasogenic BE formation. We conclude that the modified RISA method is a satisfactory measure of regional vasogenic BE in acute animal experiments.