Mechanisms underlying focal motor seizures and the Jacksonian “march” have been explored on the basis of recent physiologic data concerning the “nested ring” spatial and functional organization of motor cortex. Focal motor seizures can be understood in terms of the focal representation at motor cortex of elements controlling movement of a limb part about a single joint. The preponderance of three foci of origin of motor seizures, first reported by Hughlings Jackson, are related to lower thresholds of excitability at these loci, as demonstrated for forelimbs in the case of subhuman primates, and to the resultant bias of peripheral and central input to activate these loci. The “march” phenomenon which typically involves specific patterns of spread in the forearm, is explained in terms of the recently discovered nested ring organization. Thus the centrifugal spread of excitation from a particular locus in motor cortex would demand the pattern of spread of convulsive movements generally observed in clinical situations. The latter involves spread from face or leg to shoulder, forearm, then to hand, or conversely.

The physiological basis of activation and/or inhibition of focal motor epilepsy by peripheral stimuli is also now available on the basis of current experimental evidence. Thus the point to point coupling of periphery and motor cortex as defined in terms of control of limb parts about single forelimb joints, provides a substantial understanding of many of the clinical events sometimes termed “reflex” epilepsy.

Foci of recent cell death were identified in 10 consecutive cases of Huntington's disease in the caudate nucleus and putamen. Indirect immunohistochemical staining procedures were performed on these areas and controls using fluorescein conjugated anti-globulin and peroxidase-conjugated anti-globulin. Positive results were found when human antiserum to Cytomegalovirus was used. The possibility of abnormal antigen presence within the dying neurons in this disease is discussed.

A variety of peripheral nerve disorders may be associated with chronic renal failure. The polyneuropathy due to uremic toxins is a distal, motor and sensory polyneuropathy in which there is segmental demyelination, axonal degeneration, and segmental remyelination. The nature of the uremic toxin and the underlying mechanism of these changes is unknown.

The incidence in patients with “endstage” renal disease has fallen in recent years, severe cases now being rare, perhaps due to refinements in chronic hemodialysis, transplantation, and other therapies. However, while chronic hemodialysis stabilizes uremic neuropathy, manipulation of hemodialysis schedules may not alter its course, according to current assessment. Successful renal transplantation improves both the clinical and electrophysiological signs, even in severe uremic neuropathy.

Six cases of acute cerebellar infarction seen on a neurosurgery service in a general hospital during a twenty-six month period are reviewed. The clinical presentation, course, and treatment are presented and discussed. This is an important clinical syndrome which requires a high level of clinical suspicion for detection. The diagnosis rests primarily upon the clinical signs and symptoms. The C.T. Scan may provide useful confirmatory evidence and clarifies the differential diagnosis. Surgial treatment by resection of the infarcted tissue — mass lesion is urgently required for those patients who deteriorate progressively.

A thirty-seven year old, East Indian female was admitted to St. Michael's Hospital on July 26, 1979 complaining of headache, diplopia, nausea and vomiting.

In April of 1978 she was referred to a neurologist for investigation of headache. Neurological examination was normal. An X-ray of her skull revealed a lytic lesion, 2 cms. in diameter, in the right frontal area. A bone scan showed no abnormality. Further study was refused. A left facial “birth mark” was noted.

An ABA within-subject study design was used to assess the effect of dietary phenylalanine restriction on the visual attention span of three mentally retarded males (9, 15, and 21 years old)with phenylketonuria. Visual attention span was measured by recording the amount of time the subjects visually fixated pictures projected on a screen according to a standardized test protocol. After 4-6 weeks of baseline testing (A-phase), each subject was placed on a phenylalaninerestricted diet, designed to maintain plasma phenylalanine levels at 0.3 - 0.9 mM, for 8-14 weeks (B-phase). A return to baseline phenylalanine intake (A-phase) was achieved by surreptitiously adding sufficient L-phenylalanine to the therapeutic diets to increase plasma concentrations of the amino acid to pretreatment levels. Diet treatment (B-phase) was associated with highly significant improvementsin visual attention span in two subjects (multivariate analysis of variance, P <<0.001); the third subject, the most retarded, showed no effect. No objectivelydemonstrable change in behavior was documented in any subject. However, the results support the view that phenylalanine toxicity extends beyond early childhood and that some component of the toxicity is reversible, even in severely retarded patients with phenylketonuria.

Charles River CD male rats were randomly divided into 3 groups of five each and placed on folate deficient, folate excess, and control diets respectively. Glutamate decarboxylase GA D y-aminohutyrate aminotransferase (GABA-T), choline acetyltransferase (ChAc), and acetylcholinesterase (AChE) were assayed in the rat brains after 6 weeks of dietary treatment. Neither folate deficiency nor folate supplementation influenced the enzymes associated with GABA and acetylcholine metabolism.

An ultrastructural study of the sympathetic ganglia, dorsal sympathetic chain, and Auerbach's plexus is described in the streptozotocin diabetic rat. The observations cover the first six weeks following induction of diabetes. Degenerative changes began to appear in the axonal plasma membranes and axoplasm of unmyelinated fibers at 24 hours and were widespread by two weeks. Axonal sprouting and regenerating axons began to appear and increase in number through the 6th week. Chromatolysis in ganglion cells in sympathetic ganglia became apparent by two weeks as did degenerative changes in axons of Auerbach's plexus. This somewhat later appearance of changes in ganglion cells and Auerbach's plexus suggested the primary changes occurred in the postganglionic fibers. The cycle of change from degeneration to regeneration in the areas examined suggests either a possible toxic effect of strepiozotocin or a combination of metabolic disturbances as a cause of this neuropathy.

Injury to peripheral nerves complicating deep intramuscular injections of antibiotic and other agents is well recognized and can result in significant permanent neurological deficit. The purpose of this paper is to review the subject of nerve injection injuries, and report on a series of recent experimental studies carried out in this laboratory designed to improve our understanding of the pathophysiology of this condition and help provide a rational basis for its treatment. A wide variety of chemotherapeutic, prophylactic, and local anaesthetic agents in common use were injected into the sciatic nerve of the adult Wistar rat. Both intrafascicular and extrafascicular injections were examined. Results revealed that the site of injection was the most crucial factor in determining the degree of nerve fiber injury. Following intrafascicular injection, the degree of injury varied significantly, depending upon the specific agent injected. The most severe injuries were associated with wide-spread axonal and myelin degeneration. Pathological alterations in the nerve were evident as early as 30 minutes following injection injury. Regeneration was a constant finding in nerve damage by injection of the various agents. The mechanism of injury appeared to be a direct toxic effect of the injected compound on neural tissue, with an associated break down of the bloodnerve barrier.

A case of Herpes zoster of the mandibular nerve in an 80 year old man is reported. Herpes zoster infection affecting only the mandibular branch of the trigeminal nerve is rare, ft is proposed that the distribution of lesions is a consequence of a unique latent site of the virus within neurons of the gasserian ganglion innervating the mandibular division of the trigeminal nerve.

Balint's syndrome is usually attributed to bilateral parieto-occipital lesions. In several reported cases involvement of the frontal lobes was also documented and could be responsible for the “spasmodic fixation” often recorded in these patients. We report a case of Balint's syndrome in a patient with bilateral frontal and parieto-occipital metastases demonstrated by CTscan and confirmed by postmortem examination.

Six years after apparent complete recovery from intestinal Whipple's disease, a 56 year old man developed insidious progressive somnolence and gait ataxia. Studies showed hydrocephalus with obstruction of the aqueduct and CSF leukocytosis and elevated protein. Arachnoid biopsy during craniotomy revealed chronic inflammatory infiltration with PAS-positive macrophages. The patient died 5 years later despite two courses of antibiotic therapy. This is the first report of histologically confirmed cerebral Whippie's disease during life.

Whipple's disease is a systemic infectious disorder. Cerebral involvement even in neurologically asymptomatic patients should be sought with periodic CSF cytologic studies and a search for hydrocephalus. The possibility of cerebral Whipple's disease should be considered in the presence of unexplained hydrocephalus and/or chronic inflammatory changes in the spinal fluid, especially in those with past or active intestinal disease.