The most specific findings are fibrillations and sharp waves in
muscles corresponding to a single nerve root,
combined with normal sensory potentials from
nerves that carry that root; the latter is the result
of the preganglionic site of root compression,
leaving the cell body and distal axon unaffected
Sampling four or five relevant muscles including
the paraspinal regions is considered adequate
Late responses are often included in the nerveconduction
studies because they are sensitive to
root compression
Electrodiagnostic confirmation
that sciatica is due to a radiculopathy rather than
to an undefined musculoskeletal problem is associated
with a better outcome but the role of
EMG in sciatica has not been established and
some guidelines do not require testing