Improved Diagnosis of Amyotrophic Lateral Sclerosis by Transcranial Magnetic Stimulation in a Routine Clinical Setting
Johannes C. WSS. Adohrle, Konstantinos Spengos, Wolfgang Steinke, Michael Hennerici
Tuesday 4:00:00 PM / Room 309
To demonstrate upper motor neuron dysfunction in amyotrophic lateral sclerosis (ALS) by transcranial magnetic stimulation (TMS) in a routine clinical setting.
Central motor conduction times (CMCT) have been shown to be prolonged in ALS, but the diagnostic yield of TMS in patients without definite upper motor neuron signs (UMNS), like obvious spasticity or Babinsky´s sign, is less clear.
In 22 consecutive patients, we diagnosed classic ALS, ALS with probable UMNS, and progressive bulbar palsy, based on clinical and electromyographic evidence, imaging studies and subsequent clinical course. Shortly after initial diagnosis, we obtained motor evoked potentials in the first dorsal interosseous and anterior tibial muscles by TMS using a standard protocol, and compared CMCT and clinical findings.
Overall, 8 of 22 patients had definite UMNS of whom 7 revealed a prolonged CMCT in at least one limb, however, CMCT was also prolonged in 8 of 14 patients without definite UMNS. Among the 15 patients with a disease duration of less than 12 months at the time of TMS, were 10 patients with progressive bulbar palsy of whom 4 patients without definite UMNS demonstrated a pathological CMCT. In the other 5 ALS patients, TMS findings correlated exactly with definite (3) or only probable (2) UMNS. In 7 ALS patients with symptoms for 12 months or more, TMS demonstrated upper motor neuron involvement in 4 of 6 patients without definite UMNS.
Transcranial magnetic stimulation demonstrated upper motor neuron dysfunction in more than half of our patients without definite clinical pyramidal tract signs. It was also useful early in progressive bulbar palsy presenting without definite UMNS. In ALS without definite UMNS of 12 months duration or more, TMS revealed subclinical upper motor neuron involvement in the majority of patients, thus providing further evidence of the diagnosis.