Non-Functional Jaw Muscular Activity in Patients with Disorders of Consciousness Revealed by A Long-Lasting Polygraphy.

The presence of involuntary, non-functional jaw muscle activity (NFJMA) has not yet been assessed in patients with disorders of consciousness (DOC), although the presence of bruxism and other forms of movement disorders involving facial muscles is probably more frequent than believed. In this work, we evaluated twenty-two prolonged or chronic DOC patients with a long-lasting polygraphic recording to verify NFJMA occurrence and assess its neurophysiological patterns in this group of patients. A total of 5 out of 22 patients showed the presence of significant NFJMA with electromyographic patterns similar to what can be observed in non-DOC patients with bruxism, thus suggesting a disinhibition of masticatory motor nuclei from the cortical control. On the other hand, in two DOC patients, electromyographic patterns advised for the presence of myorhythmia, thus suggesting a brainstem/diencephalic involvement. Functional, non-invasive tools such as long-lasting polygraphic recordings should be extended to a larger sample of patients, since they are increasingly important in revealing disorders potentially severe and impacting the quality of life of DOC patients.

Effect of repetitive transcranial magnetic stimulation on action myoclonus: A pilot study in patients with EPM1.

OBJECTIVE: The objective of this study was to explore the short-term effects of repetitive transcranial magnetic stimulation (rTMS) on action myoclonus. METHODS: Nine patients with Unverricht-Lundborg (EPM1) progressive myoclonus epilepsy type underwent two series of 500 stimuli at 0.3Hz through round coil twice a day for five consecutive days. Clinical and neurophysiological examinations were performed two hours before starting the first rTMS session and two hours after the end of the last rTMS session. RESULTS: Eight patients completed the protocol; one discontinued because of a transient increase in spontaneous jerks. The unified myoclonus rating scale indicated a 25% reduction in posttreatment myoclonus with action score associated with an increase in the cortical motor threshold and lengthening of the cortical silent period (CSP). The decrease in the myoclonus with action scores correlated with the prolongation of CSP. CONCLUSIONS: Repetitive transcranial magnetic stimulation can be safely used in patients with EPM1, improves action myoclonus, and partially restores deficient cortical inhibition.

Short and long interval cortical inhibition in patients with Unverricht-Lundborg and Lafora body disease.

Myoclonus has different clinical and neurophysiological features in patients with Unverricht-Lundborg (ULD) and Lafora body disease (LBD), probably because of a different cortical hyperexcitability profile. To investigate the role of intracortical inhibition in such different presentations, we used paired-pulse transcranial magnetic stimulation (TMS) in ten ULD and five LBD patients, all with a positive molecular diagnosis. All of the patients were treated with antiepileptic drugs (AEDs). In comparison with healthy subjects, both patient groups had significantly defective short intracortical inhibition (SICI), however LBD patients, but not ULD and healthy subjects, had a clear inhibition at ISI 6 ms and ISI 10 ms. Moreover, defective long interval cortical inhibition (LICI) was found in LBD but not ULD patients. The substantial reduction in SICI suggests that both ULD and LBD patients have impaired inhibitory interneuron pools which are involved in the generation of cortical reflex myoclonus, whereas the inhibition found in LBD patients at ISI 6 and 10 ms, as well the reduced inhibition found at long intervals, suggest a more complex circuitry dysfunction possibly involving both excitatory and inhibitory systems. These findings are probably related to the high epileptogenic propensity characterizing LBD with respect to ULD and to the more severely distorted neuronal network resulting from the pathogenesis of LBD.