Table 4

Transcortical magnetic stimulation

Patient	Latency to M tibialis anterior (ms) R/L	C(MEP) amplitude (mV)	Central latency (ms)
II–2	42.9^4-150/42.7^4-150	2.0/3.5	16.6^4-150/15.0
III–1	36.0/36.2	2/1	13.7/13.5
III–2	41.1^4-150/40.9^4-150	2.3/2.9	NC/NC
III–3	39.6/40.4^4-150	1.6/2.7	13.7/17.4^4-150
III–4	38.0^4-150/36.8^4-150	4.8/4.0	NC/NC

↵4-150 Pathological values. NC=could not be calculated because the F-wave latency could not be measured.
Since neither F-wave latencies nor lumbar potentials could be determined in III-2 and III-4, no central latency could be calculated in these patients. However, the abnormal long latency to the M. tibialis anterior in these patients with only moderate peripheral motor NCV slowing suggests strongly a central involvement. Most interestingly, although severly affected, a pathological central latency could be determined in index patient III-3, which clearly demonstrates central motor involvement in this patient.