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Hemifacial spasm or somatoform disorder – postexcitatory inhibition after transcranial magnetic cortical stimulation asa diagnostic tool
Author(s) -
Kotterba S.,
Tegenthoff M.,
Malin JP.
Publication year - 2000
Publication title -
acta neurologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.967
H-Index - 95
eISSN - 1600-0404
pISSN - 0001-6314
DOI - 10.1034/j.1600-0404.2000.90281a.x
Subject(s) - hemifacial spasm , transcranial magnetic stimulation , psychogenic disease , medicine , anesthesia , psychology , stimulation , neuroscience , surgery , psychiatry , facial nerve
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.