Hemifacial spasm or somatoform disorder--postexcitatory inhibition after transcranial magnetic cortical stimulation as a diagnostic tool [In Process Citation]
Kotterba S; Tegenthoff M; Malin JP
Acta Neurol Scand 2000 May;101(5):305-10 [MEDLINE record in process]

ABSTRACT: Hemifacial spasm (HFS) presents a frequent movement
disorder. It is thought to have an organic origin. It
therefore has to be distinguished from other facial
involuntary movements, especially psychogenic tics,
because the therapeutic approach differs. The present
study opted to evaluate the diagnostic value of the
postexcitatory inhibition (pI) after transcranial
magnetic stimulation (TMS). After stimulating the
contralateral hemisphere with the conventional flat coil
and recording from the mentalis muscle, in 10 healthy
controls and 10 patients postexcitatory inhibition was
determined. PI showed no side to side difference in
healthy controls (96.9 + 12.7 ms right, 87.9 +/- 10.8 ms
left side, interhemispheric difference 6.4 +/- 3.8 ms). In
8 patients with hemifacial spasm, the duration of pI on
the non-affected side did not differ from the healthy
controls (87.9+/-43.5 ms). During spasm, pI on the
affected side shortened increasingly until no inhibition
could be induced. Afterwards the spasm pI was
prolonged significantly (up to 140 ms longer than
opposite side) before returning to normal values. Two
patients presented no side differences of pI during the
"spasm". An emotional conflict situation could be
evaluated, supporting the diagnosis of somatoform
disorder. As postexcitatory inhibition is mainly due to
cerebral mechanisms, the electrophysiological results
of the study pointed to a cortical influence on the
hemifacial spasm. TMS seems to be an
electrophysiological tool which allows a differentiation
between organic and psychogenic spasm and enables a
different therapeutic approach.

2000/15 11:00




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