The review focuses on the clinical diagnostic utility of
transcranial magnetic stimulation (TMS). The central motor conduction time (
CMCT) is a sensitive method to detect
myelopathy and abnormalities may be detected in the absence of radiological changes.
CMCT may also detect upper motor neuron involvement in
amyotrophic lateral sclerosis. The diagnostic sensitivity may be increased by using the triple stimulation technique (TST), by combining several parameters such as
CMCT, motor threshold and silent period, or by studying multiple muscles. In peripheral facial nerve
palsies, TMS may be used to localize the site of nerve dysfunction and clarify the etiology. TMS measures also have high sensitivity in detecting lesions in
multiple sclerosis and abnormalities in
CMCT or TST may correlate with motor impairment and disability. Cerebellar stimulation may detect lesions in the cerebellum or the cerebellar output pathway. TMS may detect upper motor neuron involvement in patients with atypical
parkinsonism and equivocal signs. The ipsilateral silent period that measures transcallosal inhibition is a potential method to distinguish between different
parkinsonian syndromes. Short latency afferent inhibition (SAI), which is related to central
cholinergic transmission, is reduced in
Alzheimer's disease. Changes in SAI following administration of
cholinesterase inhibitor may be related to the long-term efficacy of this treatment. The results of MEP measurement in the first week after
stroke correlate with functional outcome. We conclude that TMS measures have demonstrated diagnostic utility in
myelopathy,
amyotrophic lateral sclerosis and
multiple sclerosis. TMS measures have potential clinical utility in
cerebellar disease,
dementia,
facial nerve disorders,
movement disorders,
stroke,
epilepsy,
migraine and
chronic pain.