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Our findings confirm that the occipital cortex is hyperexcitable in the migraine interictum, both in migraine with and without aura.

Epidemiologic data on inclusion body myositis (IBM) are scarce, and possibly biased, because they are derived from larger neuromuscular centers. The present nationwide collaborative cross-sectional study, which culminated on July 1, 1999, resulted in identification of 76 patients with IBM and the establishment of a prevalence of 4.9 patients with IBM per million inhabitants in the Netherlands. Several discrepancies suggest that this may be an underestimation. The most frequently identified pitfall in diagnosing IBM was an erroneous diagnosis of polymyositis or motor neuron disease.

The idea that damage to one part of the nervous system can have effects at a distance was popular during the 19th century. Constantin von Monakow, MD, accepted this idea and blended it with the newly formulated neuron doctrine early in the 20th century to account for ipsilateral paralyses and recovery of function. He called his theory of neural depression caused by loss of inputs to structures tied to the damaged area diaschisis. In this article, we examine the origins of diaschisis and the goals of Monakow. Credit is given to Monakow for drawing needed attention to the dynamics of the nervous system, remote lesion effects, and recovery of function, even though the fine details or specifics of his theory have had a mixed reception.

Cortical hyperexcitability is a feature of "familial cortical myoclonic tremor with epilepsy" (FCMTE). However, neuropathological investigations in a single FCMTE patient showed isolated cerebellar pathology. Pathological investigations in a second FCMTE patient, reported here, confirmed cerebellar Purkinje cell degeneration and a normal sensorimotor cortex. Subsequently, we sought to explore the nature of cerebellar and motor system pathophysiology in FCMTE. Eye movement recordings and transcranial magnetic stimulation performed in six related FCMTE patients showed impaired saccades and smooth pursuit and downbeat nystagmus upon hyperventilation, as in patients with spinocerebellar ataxia type 6. In FCMTE patients short-interval intracortical inhibition (SICI) was significantly reduced. Resting motor threshold, recruitment curve, silent period, and intracortical facilitation were normal. The neuropathological and ocular motor abnormalities indicate cerebellar involvement in FCMTE patients. Decreased SICI is compatible with intracortical GABA(A)-ergic dysfunction. Cerebellar and intracortical functional changes could result from a common mechanism such as a channelopathy. Alternatively, decreased cortical inhibition may be caused by dysfunction of the cerebello-thalamo-cortical loop as a result of primary cerebellar pathology.

These findings suggest that inhibitory systems are activated to a lesser extent by TMS pulses in patients. This observation is in agreement with the hypothesized deficiency of intracortical inhibition of the visual cortex, at least in migraineurs with aura.

We suggest that interictal photophobia is common in migraine and similar across different patient populations. One pathophysiological hypothesis is that interictal photophobia is associated with cortical hypersensitivity to stimulation. The predictive validity of interictal photophobic symptoms suggests that clinical diagnosis may be aided by questioning the patient about light sensitivity in the period between attacks.

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