Small fiber neuropathy and related factors in patients with systemic lupus erythematosus; the results of cutaneous silent period and skin biopsy

Abstract Introduction Evaluating small nerve fibers in patients with systemic lupus erythematosus (SLE) using cutaneous silent period (CSP) and skin biopsy and assesssing the relationship between clinical signs, autoantibodies and neuropathic pain score. Objective - methods Fifty one SLE patients and 46 healthy volunteers were included in this study. Nerve conduction studies and CSP were performed both on upper and lower limbs in subjects. Skin biopsy was performed and the number of epidermal nerve density and IL-6 staining were evaluated. Results In SLE patients, CSP latencies were significantly prolonged both in lower and upper limbs and lower and upper extremity CSP durations were significantly shorter when compared to controls ( p < 0.001). The number of epidermal nerve was significantly lower in SLE patients when compared to healthy controls ( p < 0.001). Conclusion We detected marked small nerve fiber damage in both lower and upper limbs in SLE patients using CSP. Decreased epidermal nerve density also supports this finding.(AU)

Alteración de las fibras finas A-delta por entrampamiento del nervio mediano en la muñeca utilizando el período silente cutáneo / The impairment of A-delta fibers in median nerve compression at the wrist, using the cutaneous silent period

El síndrome del túnel carpiano (STC) es una neuropatía por entrampamiento a nivel de la muñeca que cursa con dolor, parestesias y disestesias dolorosas. El diagnóstico electrofisiológico se basa en el estudio de la neuroconducción de las fibras gruesas. Nuestra hipótesis consiste en la existencia del compromiso de las fibras nerviosas finas y que este compromiso se correlaciona con el grado de gravedad. Se evaluaron retrospectivamente 69 manos correspondientes a 47 pacientes, varones y mujeres (edad media 53.8, rango 22-87 años) y como grupo contro, 21 manos correspondientes a los lados asintomáticos de estos casos. Se realizaron estudios de neuroconducción motora, sensitiva y ondas F para clasificar a las manos según el grado de gravedad. Se realizó el período silente cutáneo (PSC) en todas las manos. Se evaluaron latencias medias y duraciones medias del PSC. Las latencias medias se hallaron significativamente prolongadas en las manos con neuropatía (84.3 ± 16.3 mseg) con respecto a las manos sin neuropatía (74.8 ± 11.6 mseg), p < 0.05. Las latencias medias se hallaron más prolongadas en las manos con neuropatía de mayor gravedad (p < 0.05). En los 3 pacientes con neuropatía grado más grave no se halló el PSC. Se demostró el compromiso de las fibras finas A-delta en los pacientes con STC, con mayor compromiso a mayor severidad. El PSC puede usarse como complemento de los estudios de neuroconducción motora y sensitiva.

Carpal tunnel síndrome (CTS) is an entrapment neuropathy of the median nerve at the wrist, that leads to pain, paresthesia and painful dysesthesia. The electrophysiological diagnosis is based upon nerve conduction studies which evaluate thick nerve fibers. Our hypothesis is that there is an additional dysfunction of small fibers in CTS, which correlates with the degree of severity of the neuropathy. A retrospective study of 69 hands that belonged to 47 patients of both sexes (mean age 53.8, years, range 22-87) was performed, and, as a control group, 21 hands which corresponded to the asymptomatic side of those patients were evaluated. Motor and sensory conduction studies, as well as F-waves were performed to classify the neuropathy according to the degree of severity. Cutaneous silent period (CSP) was elicited in all hands. Mean onset latencies and durations of CSP were evaluated. Mean onset latencies were significantly prolonged in neuropathic hands (84.3 ± 16.3 msec) compared to asymptomatic hands (74.8 ± 11.6 msec) (p < 0.05). Mean latencies of the CSP were even prolonged (p < 0.05) in hands affected by a more severe neuropathy. In the 3 hands with most severe neuropathy, a CSP could not be elicited. In CTS an impairment of A-delta fibers was recorded through the CSP. The more severe the neuropathy is, the more impairment of A-delta fibers can be found. CSP may be assessed as a complement of motor and sensory nerve conduction studies in this neuropathy.

Importância do período de silêncio cutâneo na fibromialgia e sua relação com as características da doença, distúrbios psicológicos e qualidade de vida dos pacientes / Importance of cutaneous silent period in fibromyalgia and its relationship with disease characteristics, psychological disorders and quality of life of patients

INTRODUÇÃO: O período de silêncio cutâneo (PSC) é um reflexo protetor inibitório da coluna vertebral e seus aferentes consistem em fibras nervosas A-delta. Nosso objetivo foi avaliar pacientes com fibromialgia (FM) e controles saudáveis para determinar as diferenças entre os grupos em relação à duração e latência do PSC, e quando presente, determinar se há alguma relação com as características da doença, distúrbios psicológicos e qualidade de vida. MATERIAIS E MÉTODOS: Trinta e dois pacientes com FM e 32 voluntários saudáveis foram incluídos no estudo. Os dois grupos foram comparados em relação à latência e duração do PSC em ambos os membros superiores e inferiores. Características da doença, distúrbios psicológicos e qualidade de vida dos pacientes foram avaliados utilizando o Fibromyalgia Impact Questionnaire (FIQ), e o Short Form-36 (SF-36). Os pacientes com medida de PSC igual ou inferior às do grupo controle foram comparados com aqueles com valores mais elevados do que os controles em termos de características da doença, estado psicológicos e qualidade de vida. RESULTADOS: Latências significativamente prolongadas de PSC nos membros superiores e inferiores foram determinadas em pacientes comparados com os controles. Observou-se que a prolongamento da latência do PSC no membro inferior estava associado com a gravidade da doença e incapacidade funcional. CONCLUSÕES: Latências do PCS nos membros superiores e inferiores em pacientes com FM são mais longas do que em voluntários saudáveis. Além disso, o prolongamento da latência do PSC no membro inferior está associado com a gravidade da doença e incapacidade funcional física.

INTRODUCTION: Cutaneous silent period (CSP) is an inhibitory spinal protective reflex and its afferents consist of A-delta nerve fibers. We aimed to evaluate patients with fibromyalgia (FM) and healthy controls to determine any differences between the groups in terms of CSP duration and latency, and if present, to determine whether there is any relationship with disease characteristics, psychological disorders and quality of life. MATERIALS AND METHODS: Thirty-two patients with FM and 32 healthy volunteers were included in the study. The patient and control groups were compared in terms of CSP latency and duration in both upper and lower extremities. Disease characteristics, psychological disorders and quality of life of patients were assessed using the Fibromyalgia Impact Questionnaire (FIQ) and Short Form-36 (SF-36). Patients with CSP measurements equal to or lower than those of the control group were compared with those with higher values than controls in terms of disease characteristics, psychological status and quality of life. RESULTS: Significantly prolonged CSP latencies in both upper and lower extremities were determined in patients compared to controls. We found that prolongation of CSP latency in the lower extremity is associated with disease severity and functional disability. CONCLUSIONS: CSP latencies in both upper and lower extremities in patients with FM are longer than in healthy volunteers. Moreover, prolongation of CSP latency in the lower extremity is associated with disease severity and physical functional disability.

Influence of Transcutaneous Electrical Nerve Stimulation on Cutaneous Silent Period

OBJECTIVE: To investigate the influence of high frequency transcutaneous electrical nerve stimulation (TENS) on cutaneous silent period. METHOD: Cutaenous silent period was recorded before and after high frequency TENS application in sixteen healthy adults (11 males, 5 females). Onset latency, duration, and minimum stimulation intensity to evoke cutaneous silent period were compared. In 7 male subjects, temporal changes of cutaneous silent period were observed after TENS application. RESULTS: Minimum stimulation intensity to evoke cutaneous silent period was significantly increased after high frequency TENS application (p<0.05) and yet, onset latency and duration showed no significant change. The increase in minimum stimulation intensity to evoke cutaneous silent period was maintained for 30 minutes after TENS and returned to the baseline level thereafter. CONCLUSIONS: These results suggest that high frequency TENS increase the depolarization threshold of A-delta fiber and this peripheral effect may be one of the pain control mechanisms of TENS.

The Usefulness of Cutaneous Silent Period in Diabetic Polyneuropathy

OBJECTIVE: To evaluate the usefulness of cutaneous silent period(CSP) in assessing the pain sensory function mediated by the Adelta fiber in diabetic polyneuropathy and to define the proper CSP parameter and method. METHOD: We studied 18 diabetic polyneuropathy patients and 20 age-matched healthy subjects. CSPs were recorded in the abductor pollicis brevis muscle and soleus muscle with the surface electrodes and a painful electrical stimulation was given to the mixed nerves(median and tibial nerve) and cutaneous nerve(ulnar and superficial peroneal nerve). Onset latency, end point and duration of CSP were compared between two groups. CSP parameters correlated with the motor and sensory nerve conduction parameters in diabetic polyneuropathy patients. RESULTS: CSP onset latency and end point were significantly delayed in diabetic polyneuropathy patients for both mixed nerve and cutaneous nerve stimulations. There was no difference in CSP duration between two groups. CSP onset latency was shortend and duration was prolonged in mixed nerve stimulation due to an antidromic collision, which showed a cutaneous nerve stimulation as the propor method. There was no correlation between the CSP parameters and motor and sensory nerve conduction parameters. In 3 cases, the CSPs were unable to the evoked despite the sensory nerve action potential was normally evoked. This suggests that the CSP would give an information about the Adelta fiber function than the large myelinated fiber. CONCLUSION: This study indicates that the CSP is a useful supportive electrophysiologic study to assess the Adelta fiber function in diabetic polyneuropathy. The CSP onset latency and cutaneous nerve stimulation are the useful parameter and method for the CSP.