29424ournal of , Neurosurgery, and Psychiatry 1992;55:294-299

Transcranial magnetic stimulation in pontine J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.4.294 on 1 April 1992. Downloaded from infarction: correlation to degree of paresis

A Ferbert, S Vielhaber, U Meincke, H Buchner

Abstract tion of I waves, whereas subcortical Transcranial magnetic stimulation was would affect only the descending pathways, performed in 20 patients with pontine leaving the cortex intact as an I wave generator. infarction who had initially some degree In order not to confound these effects we of . Only patients with a well investigated a group of patients with pure defined lesion on magnetic resonance pontine infarction. Finally, subclinical lesions imaging that was appropriate for the may affect the results ofTCMS-for example, neurological signs were included. Record- in multiple sclerosis2-and we were interested ings were made from the abductor pollicis whether this holds also for ischaemic lesions. brevis muscle (APB) bilaterally. The degree of hand paresis was estimated clinically and related to the following Patients and methods parameters: central motor conduction We examined 20 patients with pontine ischae- time (CMCT), interside latency difference mic infarction that had occurred over a period of total latency, and amplitude ratio of oftwo years. All patients had branch occlusion. affected to unaffected side. Increasing Patients with basilar artery occlusion were not degree of paresis was associated with included in this study. Their mean age was increasing latency parameters and 58-2 years, ranging from 23 to 77. All patients decreasing amplitude ratio. In the four were treated in our department immediately patients with severe paresis a low ampli- after their so that the results of the tude response could be evoked and CMCT neurological examination were available from was delayed by up to 10 ms. When the the hospital chart for the acute state in all 20 paresis had resolved at the time of trans- patients. Only patients who had hemiparesis at cranial magnetic stimulation CMCT was least initially for some days or weeks were normal. However, amplitude ratio was included. Patients with transient ischaemic less than 100% in all but one patient, with attacks were excluded. We excluded also seven most of the values ranging between 40%1/ patients with pure tegmental vascular syn- and 60%, which indicates a subclinical dromes (internuclear ophthalmoplegia, gaze pyramidal tract lesion. Median nerve sen- paresis, etc) or with pure sensory stroke due to

sory evoked potentials (SEP) and related pontine infarction who had no paresis at any http://jnnp.bmj.com/ interside latency difference to amplitude time. ratio N201P25 were also recorded. In con- For the purpose of this study neurological trast to TCMS, decreased amplitude ratio examination, transcranial magnetic stimula- of SEP was not associated with delayed tion, and somatosensory evoked potentials latency. Clinically, the mild degree of and (SEP) were performed in four patients in the good recovery from paresis in ventral acute state alone one to 10 days after the stroke pontine infarction was remarkable. and in 13 patients in the chronic state alone two to 27 months (mean 12-5 months) after on September 30, 2021 by guest. Protected copyright. the stroke in our outpatient clinic. The remain- Magnetic stimulation of the motor cortex ing three patients were investigated in the acute (TCMS) was introduced by Barker et al and is as well as in the chronic state. Neurological set to become a routine method in clinical examination included an estimation of the neurophysiology.' Its diagnostic value has been Department of shown in ,2 degenerative atax- Klinikum ic disorders,3 and psychogenic