Errors in diagnosis of polyneuropathy: three cases of chronic lumbosacral root impairment.

In the last years very precise diagnostic investigations have been introduced to allow accurate diagnosis of pathologies affecting the major part of peripheral nerves; nevertheless, some avoidable misdiagnosis still occurs. For instance, the neurophysiological pattern observed in chronic compression of nerve roots may mimic an axonal polyneuropathy, especially when compression occurs in post-ganglionic tract of dorsal root (in this case sensory nerve conduction studies show decreased or absent response). A clinical-neurophysiological dissociation may be noted in cases with pre-ganglionic impairment of dorsal root (clinical sensory deficit in presence of normal amplitude of sensory response). During the past two years we observed 3 cases with diagnosis of polyneuropathy that, after further studies, appeared affected by severe chronic compression of lumbo-sacral nerve roots. Our data suggest that in those cases with suspected polyneuropathy, in which the neurophysiological picture is characterized by the exclusive axonal (and myelinic) involvement of motor and/or sensory peripheral nerve of lower limbs, neuroimaging of radicular structures must be performed. These further investigations may avoid severe and irreversible damage to neural tissues.