RESUMO
We report three patients with a typical clinical picture of unilateral meralgia paresthetica in whom routine nerve conduction studies were normal. However, cortical somatosensory evoked potentials were absent after lateral femoral cutaneous nerve (LFCN) stimulation on the affected side. After stimulation of the LFCN in the anterosuperior iliac spine (ASIS) region and recording the responses distal to conventional sites (20 cm from the ASIS), sensory nerve action potentials (SNAPs) were absent in the symptomatic leg, but present in the normal leg. We suggest that thigh paresthesias may be caused by a distal LFCN lesion. Eliciting this requires recording SNAPs distal to conventional sites.
Assuntos
Plexo Lombossacral/lesões , Plexo Lombossacral/fisiopatologia , Traumatismos dos Nervos Periféricos , Nervos Periféricos/fisiopatologia , Doenças do Sistema Nervoso Periférico/fisiopatologia , Potenciais de Ação/fisiologia , Adulto , Diagnóstico Diferencial , Estimulação Elétrica/métodos , Eletrodiagnóstico/métodos , Potenciais Somatossensoriais Evocados/fisiologia , Feminino , Humanos , Masculino , Condução Nervosa/fisiologia , Doenças do Sistema Nervoso Periférico/diagnóstico , Coxa da Perna/inervação , Coxa da Perna/fisiopatologiaRESUMO
We studied medial dorsal superficial peroneal (MDSP) nerves in 52 patients with clinical evidence of mild chronic sensorimotor polyneuropathy and normal sural nerve responses, in order to assess the diagnostic sensitivity and usefulness of MDSP nerve testing in electrodiagnostic practice. To determine the effect of age on MDSP nerve parameters, 98 normal subjects were also examined. Electrodiagnostic evaluation involved studies of motor nerve conduction in tibial, peroneal, and median nerves; sensory nerve conduction in sural, MDSP, median, and radial nerves; tibial and peroneal nerve F waves; H reflexes from the soleus muscles; and needle electromyography of gastrocnemius and abductor hallucis muscles. Among the patients, 49% had low-amplitude sensory responses in MDSP nerves and 57% had either slowing of sensory conduction velocity or no sensory responses on proximal stimulation. MDSP nerve amplitude, tibial nerve motor velocity, and H reflexes were the most sensitive for detection of mild chronic symmetrical axonal sensorimotor polyneuropathy. MDSP nerve testing should be included in the routine electrodiagnostic evaluation of patients with suspected polyneuropathy and normal sural nerve responses.