Potencial evocado somatossensitivo e motor na espodilose cervical / Somatosensory and motor evoked potentials in patients with cervical spondylosis

This study investigated 54 patients with cervical spondylosis (CS) with or without symptoms caused by cervical spondylotic myelopathy. Cervical MRI, somatosensory evoked potentials (SEPs) and motor evoked potentials (MEP) from upper and lower limbs of all of these patients were examined retrospectively. Were MRI findings the gold standard and the patients were classified in three groups. Group 1 (absence of spinal cord compression); Group 2 (presence of spinal cord indentation); Group 3 (spinal cord compression with alteration of intraspinal sign). The sensitivity of SEP of four limbs was 61.9%, the same one as the SEP of lower limbs. The sensitivity of MEP of four limbs was 71.4%, of the upper limbs alone was 66.7% and of the lower limbs alone 52.4%, thus showing the importance of using this method in all four limbs when cervical spondylotic myelopathy is suspected. The results shown by the study of the tibial nerve in SEP and of the abductor digiti minimi muscle in MEP were more frequently abnormals than the results shown by the study of the median nerve and extensor digitorum brevis muscle in the three groups, suggesting that exists a onset compromising of them.

Foram estudados 54 pacientes com diagnóstico de espondilose cervical (EC) com ou sem sinais clínicos de mielopatia espondilótica. Realizou-se análise retrospectiva de todos os pacientes portadores de EC investigados por ressonância magnética (RNM) cervical, potenciais evocados somatossensitivos (PESS) e motor (PEM) de membros superiores e inferiores. A RNM foi considerada padrão-ouro e os pacientes foram divididos em três grupos. Grupo 1 (RNM sem compressão medular), Grupo 2 (apenas indentação medular) e grupo 3 (compressão medular associada a alteração do sinal medular). A sensibilidade do PESS de quatro membros foi 61,9%, similar à encontrada quando realizado o PESS apenas de membros inferiores. A sensibilidade do PEM de quatro membros foi 71,4%, em membros superiores isoladamente foi 66,7% e em membros inferiores 52,4%, mostrando a importância da realização deste método nos quatro membros quando suspeita-se de mielopatia espondilótica cervical. Os resultados encontrados pelo estudo do nervo tibial no PESS e do músculo abdutor do dedo mínimo no PEM mostrou maior percentual de achados alterados que os resultados encontrados pelo estudo do nervo mediano no PESS e do músculo extensor curto dos dedos no PEM nos três grupos, sugerindo que existe um comprometimento inicial deles.

P3 event related cerebral evoked potential in chronic pain patients.

P3 component of event related cerebral evoked potentials has been applied as an index of information processing in a wide variety of normal and cognition impaired subjects. The present study was undertaken to examine possible changes in central nervous system processing and subjective appraisal, indexed by cerebral evoked potentials (N200 & P300), in 20 pain free controls and 20 subjects suffering from chronic pain (cervical spondylosis and low backache, sciatica). Standard auditory 'Odd ball' paradigm involving simple discrimination task of concentrating on infrequent (target) stimulus and ignoring the frequent stimulus (non-target) was employed. Evoked response trial of discriminating 32 target stimuli out of 160 total presented (20% target and 80% non target, randomly) were replicated and analysed by computer. There was significant increase in P3 latency in patients suffering from pain as compared to age and sex matched controls, suggesting change in cognitive functions.