Clinical and electromyographic deep tendon reflexes in polyneuropathy: diagnosti

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Acta Neurol Scand. 2008 Jul 29.

Clinical and electromyographic deep tendon reflexes in

polyneuropathy: diagnostic value and prevalence

*Sharma KR, Saadia D, Facca AG, Resnick S, Ayyar DR.

Department of Neurology, University of Miami School of Medicine,

Miami, FL, USA.

Background - Evidence is accumulating that patients with

polyneuropathy may present with normal clinical deep tendon reflexes

(C-DTR). There are few studies that assessed the diagnostic utility

of electromyographically recorded DTR (Er-DTR) in patients with

polyneuropathy.

Objectives - The objectives of this study were twofold: (i) to

evaluate the prevalence of preserved C-DTR in polyneuropathy; (ii)

diagnostic value of Er-DTR latency measurement in patients with

polyneuropathy.

Methods - We prospectively studied 38 controls and 185 patients with

polyneuropathy. All subjects had evaluation of C-DTR, Er-DTR obtained

from right biceps brachii (BR), right patellar (PR) and bilateral

ankle reflexes (AR).

Results - Of these 185 patients, 118 (63.8%) had chronic axonal

neuropathy (CAN), 49 (26.5%) demyelinating polyradiculoneuropathy

(DPN) and 18 (9.7%) small fiber neuropathy (SFN). The C-DTR were

normal in 65 patients whereas 39 of these 65 (60%) patients had

abnormalities of Er-DTR at one or more sites. Er-DTR latencies in

patients with polyneuropathies were prolonged at all sites compared

with controls (P < 0.01). Among patients with various types of

polyneuropathies the Er-DTR, mean latencies at all the sites and

latency indicative of demyelination (>150% of the normal mean) were

higher in patients with DPN than that of CAN or SFN (P < 0.01).

Conclusions - We conclude that C-DTR are preserved in 35.1% of the

patients with polyneuropathies and Er-DTR should be performed in such

patients in order to provide electrophysiological evidence of a

polyneuropathy. Er-DTR are useful in distinguishing axonal from

demyelinating disorders of peripheral nerve, and detection of

subclinical involvement of large fibers in SFN.