Changes in focal interictal epileptiform activity during and after the performance of verbal and visuospatial tasks in a patient with intractable partial seizures.

An 18-year-old male with intractable complex partial seizures is described in whom localised epileptiform discharges in the EEG were influenced in a specific manner by different cognitive tasks. The patient had impaired verbal skills but above average visuospatial ability, and seizures probably arising in the left temporal lobe. Comparison of verbal and visuospatial tasks showed that focal epileptiform activity was suppressed or enhanced depending on the nature of the immediate and preceding cognitive tasks. The finding of particular interest was the activity of a posterior temporal spike focus only during rest periods after verbal tasks, by contrast with an independent mid-to-anterior temporal focus that was suppressed during verbal tasks.

Repetitive nerve stimulation of anconeus in the assessment of neuromuscular transmission disorders.

Repetitive nerve stimulation of the anconeus muscle is described. Control studies showed the test to be reliable and well tolerated over a range of stimulus frequencies and train lengths. Sixty-one patients with primary disorders of neuromuscular transmission were tested. Repetitive nerve stimulation of anconeus was abnormal in 2 of 21 patients with ocular myasthenia, but showed a significant decrementing response in 16 of 30 patients with generalized myasthenia gravis. In comparison with other muscles, repetitive nerve stimulation of anconeus was more sensitive than abductor digiti minimi, but equally sensitive as deltoid. The test may also be used to help characterize other disorders of neuromuscular transmission such as congenital myasthenia or the Lambert-Eaton myasthenic syndrome. Compared with single fibre EMG on extensor digitorum communis, repetitive stimulation of anconeus was usually, but not always, a less sensitive method of detecting a neuromuscular transmission disorder.

Nerve conduction studies in experimental non-freezing cold injury: II. Generalized nerve cooling by limb immersion.

After immersion of the hind limb of the rabbit, up to the lower thigh, in a waterbath, at 1 degree C for 10 to 14 hours under light anesthesia, there was evidence of persistent nerve damage to the tibial nerve, which varied in severity in different animals. Nerve conduction studies, carried out within 24 hours of removal from the bath, showed that in a proportion of the motor and/or afferent fibers, there was conduction failure between the knee and ankle. This was followed, over the next 48 hours, by distal degeneration of the affected fibers. No persistent conduction block was seen. After distal degeneration had occurred, maximal conduction velocity was mildly reduced, suggesting that the fastest-conducting motor and afferent fibers had been particularly affected. Morphological studies confirmed preferential large myelinated fiber degeneration, the earliest lesions being seen in the leg at the level of the upper calf. Limb edema was not seen after cooling, and there was no histological evidence of muscle necrosis or damage to blood vessels. No abnormalities were seen in 4 control animals after hind limb immersion for 12 hours at temperatures of 30 to 35 degrees C. Possible reasons for the proximal site of myelinated nerve fiber damage during hindlimb cooling are discussed.

Nerve conduction studies in experimental non-freezing cold injury: I. Local nerve cooling.

In rabbits, the tibial nerve was exposed in the lower thigh under general anesthesia and cooled in a metal trough at 1 to 2 degrees C or 5 degrees C for 2, 3, or 4 hours. Nerve conduction studies showed local failure of conduction at the site of cooling which persisted after rewarming, and which was followed by distal degeneration of affected fibers. No persistent conduction block was seen. Changes in maximal velocity indicated that the fastest-conducting motor and afferent axons had been preferentially affected. Histological findings in nerves examined at different intervals after cooling confirmed the physiological evidence of primary axonal damage, affecting particularly large diameter fibers. Paranodal demyelination was inconspicuous and restricted to regions just proximal to sites of axonal degeneration. No segmental demyelination was seen. These results clarify previous uncertainties as to the time-course and distribution of nerve damage after local cooling at temperatures just above freezing point.

Susceptibility to pressure neuropathy distal to a constricting ligature in the guinea-pig.

Silk ligatures were tied round the sciatic nerve in guinea-pigs and left in place in order to produce persistent nerve constriction. Serial nerve conduction studies over the following 9 weeks showed a reduction in motor conduction velocity distal to the ligature. The presence of axonal atrophy in tibial nerve fibres in the leg was subsequently confirmed by histological studies. These changes were not seen in a second group of animals in which similar ligatures were tied but removed after 6 hours. When the ligatures were left in place, the animals developed local plantar nerve lesions in the sole of the foot on the affected side, which were thought to be due to pressure from the floor of the cage. Local pressure changes of varying severity were seen in the foot in all the constricted nerves, but were only occasionally found in control nerves from the opposite foot, or in nerves which had been constricted for a few hours by ligatures which were then removed. These results suggest that atrophic nerve fibres distal to a persistent constriction may be particularly sensitive to local pressure.

Acute polyradiculoneuropathy complicating systemic lupus erythematosus.

Two elderly patients with systemic lupus erythematosus (SLE) are presented. Both developed an acute polyradiculoneuropathy which is an unusual complication of this disease. Features of their presentation are discussed.

Peripheral neuropathy associated with the sicca syndrome.

Three patients with the sicca syndrome and chronic sensory neuropathy are described; in two of them neuropathy was the presenting feature of the disease. The sicca syndrome can give rise to a characteristic neurological syndrome comprising areflexia and asymmetrical sensory loss, particularly of proprioception, in the limbs. This is often associated with tonic pupils and trigeminal anaesthesia.

Rupture of intracranial vascular lesions during arteriography.

Four cases with ruptured intracranial vascular lesions during angiography and confirmed radiologically are presented to emphasise a dangerous complication of the procedure.