Threshold intensity and central motor conduction time in patients with monomelic amyotrophy: a transcranial magnetic...

To determine the Cortical threshold intensity (TI) and central motor conduction time (CMCT) in patients with monomelic amyotrophy (MMA).

TI and CMCT were evaluated by means of transcranial magnetic stimulation in 18 patients of MMA and 12 healthy controls at the clinical neurophysiology laboratory, department of neurology, All India Institute of Medical Sciences, New Delhi.

The mean age of patients was 23.6 (SD 6. 7) years and of controls was 24.3 (SD 3.2) years (p > 0. 05). The mean TI in patients was 60.83% (SD 11.28) on ipsilateral and 60% (11.5%) on contralateral cortex stimulation. In controls, the mean TI was 66.67% (SD 11.5) on one side and 65% (11.87%) on contralateral cortex stimulation. There was no significant difference in the TI between these two groups (p > 0.05). The mean CMCT in patients was 8.3 (SD 1. 7) ms on ipsilateral and 9.4 (SD 1.6) ms on contralateral cortex stimulation (p > 0.05). In controls CMCT was 8.3 (SD 1.8) ms on one side and 8.6 (SD 1.4) ms on contralateral cortex stimulation. Upper limit of normal CMCT was 12.7 ms.

As compared to controls there was no significant abnormality in TI and CMCT was normal in all except two patients where it was marginally prolonged. This could be because of excessive loss of anterior horn cells.