Electrophysiological study of posterior antebrachial cutaneous nerve in a sample of normal subjects

Posterior femoral cutaneous nerve sensory conduction study in a sample of apparently healthy Egyptian volunteers

Background

Posterior femoral cutaneous nerve (posterior cutaneous nerve of the thigh) is a sensory nerve arises from the sacral plexus. Its terminal part supplies the skin of the posterior surface of the thigh and popliteal fossa, and it extends for a variable length below the popliteal fossa till the mid-calf region. The aim was to assess the posterior femoral cutaneous nerve antidromic sensory conduction technique and estimate its different sensory nerve action potential parameters’ reference values in a sample of apparently healthy Egyptian participants. One hundred and twenty lower limbs of 60 apparently healthy Egyptian volunteers were included. Clinical evaluation and sensory conduction study for the posterior femoral cutaneous nerve were done.

Results

Posterior femoral cutaneous nerve sensory nerve action potential was elicited in 98 lower limbs (81.6%) of 52 individuals (86.7%). The obtained results of different parameters of posterior femoral cutaneous nerve sensory nerve action potential were as the following: onset latency (2.04 ± 0.21 ms), peak latency (2.86 ± 0.25 ms), conduction velocity (59.45 ± 6.36 m/s) and amplitude (6.16 ± 2.29 μV). No significant differences between the two genders were found regarding different parameters of posterior femoral cutaneous nerve sensory nerve action potential except for amplitude which was significantly larger among male participants (P = 0.030). No significant differences between the right and left lower limbs were found regarding different parameters of sensory nerve action potential. There was a statistical significant negative correlation between age and posterior femoral cutaneous nerve conduction velocity (P = 0.008). There was a statistical significant positive correlation between height and peak latency (P ≤ 0.0001), as well as, a statistical significant negative correlation between height and conduction velocity (P ≤ 0.0001). There was a statistical significant negative correlation between body mass index and posterior femoral cutaneous nerve peak latency (P = 0.008).

Conclusions

The research provides a reliable electrophysiological antidromic sensory conduction study for the posterior femoral cutaneous nerve and normal cut-off reference values for posterior femoral cutaneous nerve sensory nerve action potential parameters. This is essential for the evaluation of suspected posterior femoral cutaneous nerve lesions.

A novel method to measure sensory nerve conduction of the posterior antebrachial cutaneous nerve

INTRODUCTION/AIMS

Posterior antebrachial cutaneous (PABC) nerve conduction studies could be useful for distinguishing PABC neuropathy from C7 radiculopathy. In the conventional method using an antidromic method, the sensory nerve action potential (SNAP) is sometimes followed by a large volume-conducted motor potential. In this report we describe a reliable nerve conduction study using an orthodromic method for recording SNAPs of the PABC nerve.

METHODS

Thirty-six healthy volunteers participated in this study. PABC SNAPs were recorded by placing a surface-active electrode 2 cm anterior to the lateral epicondyle. The PABC nerve was stimulated 10 cm distal to the active recording electrode along a line from the recording point to the mid-dorsum of the wrist, midway between the radial and ulnar styloid processes. We also performed PABC nerve conduction studies using an antidromic method and compared the findings.

RESULTS

PABC SNAPs were recorded bilaterally from all subjects. The mean peak-to-peak amplitude for SNAPs was 13.4 ± 4.8 μV. Mean maximum conduction velocity was 62.7 ± 3.9 m/s and mean negative peak conduction velocity was 51.2 ± 2.6 m/s. The mean side-to-side difference in amplitude was 22.1 ± 16.0%. The mean amplitude of SNAPs obtained by our method was 48.9% higher than that of SNAPs obtained by the conventional method (13.4 vs 9.0 μV; P < .001). In contrast to the conventional method, our method enabled SNAPs to be recorded without a volume-conducted motor potential.

DISCUSSION

The higher mean amplitude of SNAPs with our method enables them to be obtained easily.

Association between carpal tunnel syndrome and trigger finger: a clinical and electrophysiological study

Background

Carpal tunnel syndrome is a prevalent mononeuropathy. Trigger finger is a flexor stenosing tenosynovitis. The aim of the study was to assess the concomitant occurrence of carpal tunnel syndrome and trigger finger in the same hand among patients presented with idiopathic carpal tunnel syndrome or idiopathic trigger finger. The study included 110 hands (75 patients) presented with carpal tunnel syndrome or trigger finger and 60 asymptomatic hands (46 apparently healthy individuals). Clinical assessment and neurophysiological evaluation were done.

Results

Regarding the presenting clinical complaints, there were 76 hands (69.1%) from 48 patients (64.0%) presented with idiopathic carpal tunnel syndrome. There 34 hands (30.9%) from 27 patients (36.0%) presented with idiopathic trigger finger. Classification of the patients into three groups depending on the final diagnosis: (I) carpal tunnel syndrome group, 57 hands (51.8%) with only carpal tunnel syndrome from 36 patients (48.0%); (II) trigger finger group, 25 hands (22.7%) with only trigger finger from 22 patients (29.3%); and (III) carpal tunnel syndrome with trigger finger group, 28 hands (25.5%) with both conditions from 24 patients (32.0%); and among them, seven patients had contralateral hand carpal tunnel syndrome only. The duration of complaints among the carpal tunnel syndrome with trigger finger group was significantly shorter than that in the other two groups. There were statistically significantly higher values of patient global assessment of hand symptoms and effect of hand symptoms on function and quality of life among the carpal tunnel syndrome with trigger finger group versus the other two groups. There was no statistically significant difference between the carpal tunnel syndrome with trigger finger group versus the carpal tunnel syndrome group regarding different classes of the Padua neurophysiological classification scale. The most common digit to have trigger finger was the middle finger in 19 hands (35.8%).

Conclusions

The concurrent presentation of idiopathic carpal tunnel syndrome and idiopathic trigger finger in the same hand is common. Each of them could be associated with the other one. The symptoms of one of them usually predominate the patient’s complaints. The identification of this association is essential for proper diagnosis and comprehensive management of patients presented with these conditions.

Superficial radial neuropathy: an unobserved etiology of chronic dorsoradial wrist pain

Background

Superficial radial neuropathy is considered an uncommon cause of chronic dorsoradial wrist pain. Its clinical diagnosis is usually missed. The purpose of the research was to investigate the existence of superficial radial neuropathy as a cause of chronic dorsoradial wrist pain. The study included 98 upper limbs obtained from 72 patients [58 women (80.6%)] with a primary complaint of chronic dorsoradial wrist pain and 91 asymptomatic upper limbs obtained from 63 apparently healthy individuals [46 women (73.0%)] as a control group. Clinical assessment and superficial radial nerve conduction study were done.

Results

No significant differences between patients and control group were present regarding sex and age. Among the participated patients, there were 29 upper limbs (29.6%) from 26 patients (36.1%) who had superficial radial neuropathy proved clinically and electrophysiologically. From them, three patients (11.5%) had bilateral superficial radial neuropathy. It was the solitary cause of chronic dorsoradial wrist pain in 15 upper limbs (51.7%) from 13 patients (50%). The remaining patients were associated with other musculoskeletal wrist conditions. The most common associated local wrist pathology was de Quervain’s disease in 8 upper limbs (27.6%) from 8 patients (30.8%).

Conclusions

Superficial radial neuropathy is common among patients with chronic dorsoradial wrist pain and should be considered in the differential diagnosis.