Delusions and cyclosporine toxicity.

examination unremarkable except for some skin changes in the previously irradiated area. Chest x ray and bone scan were normal. Myelography revealed minor posterior pro-trusion of L5/S1 disc on flexion of the back. Cerebrospinal fluid contained normal cellular constituents but elevated protein at 0-8 g/litre. Motor conduction velocities in left posterior tibial and both lateral popliteal nerves were normal as were sensory conduction velocities in superficial peroneal nerves. Electromyography of left gastrocnemius and peroneus longus revealed fasciculations, complex repetitive discharges and positive sharp waves with reduced voluntary activity suggesting denervation in the territory of L5 and SI myotomes. Surface electromyography showed profuse fasciculations in the legs below the knee bilaterally, fewer in the right upper leg and none in the left upper leg or arms. By June 1990 movements of both feet were weaker and fasciculations were also visible in the hamstrings bilaterally. Both ankle jerks were absent. Nerve conduction studies again showed normal motor and sensory conduction times and amplitudes in the upper and lower limbs. Proximal conduction assessed by F-waves was also normal. Central motor conduction time measured by magnetic cort-ical stimulation was normal in both upper and lower limbs. Electromyography from right tibialis anterior showed fasciculations, motor units of prolonged duration and high amplitude, and a discrete interference pattern. Electromyography from the right vastus lateralis showed fasciculations, recurrent trains of motor unit potentials, some large motor unit potentials and a moderate interference pattern. Electromyography of the arms was normal. Motor unit counting revealed reduction in number and increase in size of motor units from the extensor dig-itorum brevis bilaterally, consistent with anterior horn cell loss. Following lumbar field irradiation a slowly evolving painless amyotrophy may develop, with lower motor neuron paresis and absent or depressed tendon reflexes.3 Fasciculation of affected muscles is variable, but absence of pain or sensory signs and normal sensory nerve conduction velocities are characteristic. Myokymic discharges on electromyo-graphy are also a typical feature.4 In this case the onset of symptoms was 23 years following radiotherapy. Despite this, the characteristic clinical picture and electro-physiological evidence favour x-irradiation as the cause. Lumbar root infiltration may be excluded by the absence of pain and sensory features, the very slow rate of deterioration and normal radiographic studies whilst the localisation of abnormalities to the irradiated area of the nervous system distinguishes this condition from amyotrophic lateral scleroSiS. The development of radiation-induced neuropathy is only partially dependent on …