Assessment of cortico-spinal tract impairment in multiple system atrophy using transcranial magnetic stimulation.
OBJECTIVE
Among Parkinsonian syndromes, pyramidal signs suggesting cortico-spinal impairment are a hallmark of multiple system atrophy (MSA). Although it is crucial to diagnose correctly this disease to choose the appropriate treatment, the available diagnostic criteria lack sensitivity. Cortical excitability patterns assessed by transcranial magnetic stimulation (TMS) do not differentiate Parkinsonian disorders. TMS using triple stimulation technique (TST) accurately detects cortico-spinal impairment. We hypothesized that this technique could detect such impairment in MSA patients.


METHODS
The TST was applied along with single and paired-pulse TMS to 31 patients fulfilling the diagnostic criteria for MSA-P (n=10), MSA-C (n=4), progressive supranuclear palsy (PSP; n=6) and Idiopathic Parkinson's disease (IPD; n=11) and 11 control subjects.


RESULTS
Single and paired-pulse TMS patterns did not differ between any patient group. The TST pattern was abnormal in five MSA-P, one MSA-C and one PSP patients but not in IPD patients or controls. The mean TST ratio for MSA-P (86.6%) was significantly different from IPD (99.1%; p<0.05) whereas ratios for MSA-C (92.1%) and PSP (93.3%) were not different from IPD or controls (99.5%).


CONCLUSIONS
These results suggest that TST is effective to assess cortico-spinal impairment in MSA.


CONCLUSIONS
TST might be useful for the diagnosis of atypical Parkinsonism.
Eusebio
A
A
Pôle des Neurosciences Cliniques, Fédération de Neurologie, CHU Timone, 264 rue Saint-Pierre, 13005 Marseille, France. a.eusebio@ion.ucl.ac.uk
Azulay
J-P
JP
Witjas
T
T
Rico
A
A
Attarian
S
S
D000368:Aged; D000369:Aged, 80 and over; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000473:pathology* / Q000503:physiopathology*; D010300:Parkinson Disease / Q000503:physiopathology; D011712:Pyramidal Tracts / Q000503:physiopathology*; D013494:Supranuclear Palsy, Progressive / Q000473:pathology / Q000503:physiopathology; D050781:Transcranial Magnetic Stimulation