Prolonged cortical relay time of long latency reflex and central motor conduction in patients with spinocerebellar ataxia type 6.
OBJECTIVE
Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disorder characterized by a slowly progressive ataxia and dysarthria. Anatomically. SCA6 was said to affect only the cerebellum. However, ithasbeen argued that SCA6 may involve widespread regions of the brain. This study was designed to investigate the electrophysiological functions of the central nervous system in patients affected with SCA6.


METHODS
Nine patients with SCA6 and 10 normal, age-matched control subjects were included in the study. The motor evoked potentials, somatosensory evoked potentials, and long latency reflex (LLR) of the hand muscle were measured to evaluate the functions of the central nervous system.


RESULTS
Significantly delayed LLR, as well as prolonged cortical relay time (CRT) and central motor conduction time (CMCT) of the hand muscle, were noted in the patients with SCA6.


CONCLUSIONS
The prolongation of CMCT andCRT suggested that SCA6 disturbed the functions of the corticospinal tract and the transcortical polysynaptic pathways from the sensory to motorcortices. It seems likely that the CNS dysfunction caused by SCA6 is not limited to the structures that are anatomically abnormal. Furthermore, the prolongation of CMCT alone does not seem to suffice to differentiate between various types of autosomal dominant cerebellar ataxias. Molecular analysis is indispensable for the diagnosis of different genetic types of SCA.
Lee
Yi-Chung
YC
The Neurological Institute, Taipei Veterans General Hospital, #201, Sec. 2, Shih-Pai Road, Peitou District, Taipei 112, Taiwan.
Chen
Jen-Tse
JT
Liao
Kwong-Kum
KK
Wu
Zin-An
ZA
Soong
Bing-Wen
BW
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D019054:Evoked Potentials, Motor; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D020754:Spinocerebellar Ataxias / Q000175:diagnosis / Q000503:physiopathology*