Ten patients developed a subacute lower motor neuron syndrome as a remote effect of Hodgkin's disease or other lymphoma. The illness usually followed a benign course independent of the activity of the underlying neoplasm. Seven of the patients improved spontaneously, and 3 became neurologically normal. Two patients died of intercurrent infections related to immunosuppression. Neuropathological examination of these 2 patients and 3 previously reported cases showed prominent neuronal degeneration restricted to the anterior horns of the spinal cord and mild posterior column demyelination. Demyelination was also present in the anterior roots of our autopsied patients and was accompanied by large, hyperchromatic Schwann cells. The cause of the illness is obscure, but both radiation therapy and opportunistic infection may be contributing factors. Attempts at virus isolation have been unsuccessful. The syndrome should be distinguished from the more common direct effects of lymphoma on the nervous system, since its identification spares the patient additional, potentially harmful therapy.

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A minority of normal humans experience paraesthesias (usually tingling) projected to the contralateral hand in response to individual transcranial magnetic coil (MC) pulses. The cortical source of the paraesthesias was sought by comparing their incidence with that of muscle responses to focal MC stimulation with either a figure 8 MC or with edge stimulation of a tilted round MC in 4 susceptible subjects. In all 4, paraesthesias were best felt with MC stimulation either at, or anterior to sites yielding movement, implying an initial source in precentral gyrus (and possible premotor cortex), rather than parietal cortex. In the two subjects exhibiting the strongest paraesthesias, the threshold for the paraesthesias was less than that for movement in the relaxed arm. The optimal site of the paraesthesias within the hand was usually in the digits, but differed among subjects. Motor responses and paraesthesias following a given stimulus occurred at different sites in the hand, implying that excitation of differing sets of motor cortical neurons subserved sensory and motor responses. In only one subject were the paraesthesias sufficiently reproducible to warrant interacting electrical digital and transcranial MC pulses. The data suggested that central processing of the response to the MC pulse is slowed by an antecedent digital stimulus, but the delay for perception of each type of stimulus does not greatly differ. The central sense of movement (Amassian et al., 1989a) elicited by MC stimulation of motor cortex is compared with the paraesthesias. Both are attributed to brief, high frequency discharge by motor cortical neurons accessing the perceptual system more readily than after excitation of post-central gyrus, which requires prolonged repetitive stimulation (Libet et al., 1964). Given also the normal pattern of muscle responses in the 4 subjects, their paraesthesias are best explained by a heightened sensitivity of the perceptual system to the motor cortical response to MC stimulation.