Compressive neuropathy of the first branch of the lateral plantar nerve: a study by magnetic resonance imaging / Neuropatia compressiva do primeiro ramo do nervo plantar lateral: estudo por ressonância magnética

Abstract Objective: To assess the prevalence of isolated findings of abnormalities leading to entrapment of the lateral plantar nerve and respective branches in patients complaining of chronic heel pain, whose magnetic resonance imaging exams have showed complete selective fatty atrophy of the abductor digiti quinti muscle. Materials and Methods: Retrospective, analytical, and cross-sectional study. The authors selected magnetic resonance imaging of hindfoot of 90 patients with grade IV abductor digiti quinti muscle atrophy according to Goutallier and Bernageau classification. Patients presenting with minor degrees of fatty muscle degeneration (below grade IV) and those who had been operated on for nerve decompression were excluded. Results: A female prevalence (78.8%) was observed, and a strong correlation was found between fatty muscle atrophy and plantar fasciitis in 21.2%, and ankle varices, in 16.8% of the patients. Conclusion: Fatty atrophy of the abductor digiti quinti muscle is strongly associated with neuropathic alterations of the first branch of the lateral plantar nerve. The present study showed a significant association between plantar fasciitis and ankle varices with grade IV atrophy of the abductor digiti quinti muscle.

Resumo Objetivo: Avaliar a prevalência de achados isolados que causam compressão do primeiro ramo do nervo plantar lateral em pacientes com queixa de dor crônica no calcanhar, cujos exames de ressonância magnética mostraram atrofia gordurosa seletiva completa do músculo abdutor do quinto dedo. Materiais e Métodos: Estudo retrospectivo, analítico e transversal. Selecionamos exames de ressonância magnética do retropé de 90 pacientes que apresentavam atrofia muscular grau IV do abdutor do quinto dedo utilizando a classificação de Goutallier e Bernageau. Foram excluídos do estudo pacientes com níveis menores de degeneração muscular (abaixo do grau IV). Resultados: Houve predomínio do sexo feminino de 78,8% e alto índice de concordância da atrofia gordurosa do músculo abdutor do quinto dedo com fasciite plantar e varizes no tornozelo, respectivamente, encontrados em 21,2% e 16,8% dos pacientes. Conclusão: Atrofia gordurosa do músculo abdutor do quinto dedo está fortemente associada a alterações neuropáticas do primeiro ramo do plantar lateral. Nosso estudo mostrou associação significativa entre a fasciite plantar e varizes do tornozelo com atrofia grau IV do abdutor do quinto dedo.

Plantar Nerve Injuries Related to Calcaneal Fractures

OBJECTIVE: We investigated plantar nerve injuries associated with calcaneal fracture and severity of disability. METHOD: From July, 2001 to June, 2002, twelve patients who had calcaneal fractures with persistent foot pain and paresthesia were included in our study. We examined electromyography for medial and lateral plantar nerve, inferior calcaneal nerve, also evaluated types of calcaneal fracture and severity of pain and disability with nerve injury. RESULTS: The intraarticular types were 13 cases, extraarticular type was 1 case and communited types were 2 cases. In the electromyographic findings, the 9 cases were diagnosed asneuropathy. In a cases with neuropathy, 8 persons complained over moderate degree of pain and all persons complained over moderate degree of walking disability. However one of three persons without neuropathy complained over moderate degree of walking disability. So disability tended to be more severe in cases with neuropathy. CONCLUSION: We think that neuropathy associated with calcaneal fracture is a cause of aggravation of pain and walking disability, and electromyography for nerves of foot will be needed in the calcaneal fracture.

Distal Motor Nerve Conduction Studies of Medial Plantar Nerve, Lateral Plantar Nerve and Inferior Calcaneal Nerve

OBJECTIVE: To determine the reference values for the diagnosis of isolated entrapment neuropathies of medial and lateral plantar nerve and inferior calcaneal nerve distal to the tarsal tunnel. METHOD: The subjects were neurologically healthy 30 adults (15 males, 15 females). Distal motor nerve conduction study of medial and lateral plantar nerves and inferior calcaneal nerve was performed. The recording muscles for medial and lateral plantar nerves and inferior calcaneal nerve were flexor hallucis brevis, flexor digiti minimi brevis, and abductor digiti minimi pedis, respectively. The stimulation was done at distal and proximal to the tarsal tunnel to differentiate the tarsal tunnel syndrome and the entrapment neuropathy of distal to the tarsal tunnel. The distance of recording and distal stimulation site was fixed to 10 cm for medial and lateral plantar nerves. The skin temperature was maintained 33degrees C or above. The proximal latency, distal latency, peak to peak amplitude, conduction velocity and residual latency were measured. The reference values were obtained by 95 percentile values. RESULTS: The reference values for the diagnosis of isolated entrapment neuropathies of medial plantar nerve, lateral plantar nerve and inferior calcaneal nerve distal to tarsal tunnel are as follows. 1) Medial plantar nerve: distal latency, > 4.3 msec; side to side difference, > 0.7 msec 2) Lateral plantar nerve: distal latency, > 4.1 msec; side to side difference, > 0.6 msec 3) Latency difference of medial and lateral plantar nerve: > 0.7 msec 4) Inferior calcaneal nerve: distal latency, > 4.3 msec; distal peak latency, > 7.2 msec; side to side difference of distal onset latency, > 1.5 msec; side to side difference of distal peak latency, > 0.8 msec; residual latency, > 3.0 msec CONCLUSION: The distal motor nerve conduction method used in this study and the reference values could be used to differentiate entrapment neuropathies of medial and lateral plantar nerve and inferior calcaneal nerve distal to the tarsal tunnel from tarsal tunnel syndrome.