Focal Vibration Alters Human Digital Sensory Nerve Action Potentials: A Pilot Study

Introduction. We studied the impact of vibratory stimulation on the electrophysiological features of digital sensory nerve action potential (SNAP). Methods. The antidromic digit 3 SNAP was recorded in 19 healthy adults before, during, and after applying a vibration to either 3rd or 5th metacarpal phalangeal joint (MCPJ) at 60 Hz and amplitude of 2 mm. 100% supramaximal stimulus intensity was performed in 5 subjects (randomly selected from the 19 subjects) where the SNAP sizes were recorded. Results. The amplitude of digit 3 SNAP declined to 58.9 ± 8.6 % when a vibration was applied to MCPJ digit 3. These impacts did not change by increasing the electrical stimulus intensity. The SNAP regained its baseline value immediately after the cessation of vibration stimulation. The magnitude of size reduction of digit 3 SNAP was less when vibration was moved to from MCPJ of digit 3 to MCPJ of digit 5. Discussion. The marked drop of the SNAP size during vibratory stimulation reflects the decreased responsiveness of Aβ afferents to electrical stimulation, which deserve further investigation in the study of focal vibration in neurorehabilitation.

Clinical predictors of surgical outcomes of severe carpal tunnel syndrome patients: utility of palmar stimulation in a nerve conduction study

Background Carpal tunnel syndrome is a common peripheral nerve compression disorder. However, there is no established opinion regarding the predictors of symptom improvement after surgery. This study aimed to identify the predictors of surgical outcomes of severe carpal tunnel syndrome patients. Methods In the patients who underwent a carpal tunnel syndrome surgery, we selected the patients who had a preoperative Bland’s classification of grade 5 or 6, and assessed for the changes in Bland’s classification grade before and after surgery. Those who showed improvement from preoperative grades 5–6 to postoperative grades 1–4 comprised the improvement group. In contrast, those who did not show improvement and had postoperative grades 5 or 6 comprised the non-improvement group. In a nerve conduction study, amplitudes of the compound muscle action potential and sensory nerve action potential of the palms were assessed between the improvement and non-improvement groups. Results Among the 60 hands of 46 patients who had a preoperative Bland’s classification of grade 5 or 6, 49 hands of 37 patients comprised the improvement group, and 11 hands of 9 patients comprised the non-improvement group. The amplitudes of the compound muscle action potential and sensory nerve action potential of the palms before surgery were significantly higher in the improvement group. The degree of improvement in Bland’s classification grade was correlated with the degree of clinical symptom improvement. Conclusions Amplitudes of compound muscle action potential and sensory nerve action potential before surgery induced by palmar stimulation can predict improvements in nerve conduction study scores and clinical findings after surgical treatment.

PERAN PEMERIKSAAN ELEKTROFISIOLOGI DALAM DIAGNOSIS SINDROM MILLER-FISHER

Sindrom Miller-Fisher merupakan salah satu varian Sindrom Guillain-Barre yang memiliki gambaran klinis unik dengan trias klasik optalmoplegia, ataksia dan arefleksia. Pemeriksaan penunjang pada Sindrom Miller-Fisher berperan penting karena beberapa kondisi penyakit juga dapat bermanifestasi seperti trias klasik Sindrom Miller-Fisher. Penunjang berupa analisis cairan serebrospinal, pencitraan otak, biomarker antibodi GQ1b telah banyak digunakan untuk menegakkan diagnosis Sindrom Miller-Fisher namun memiliki keterbatasan. Pemeriksaan elektrofisiologi kemudian banyak diteliti karena selain menunjang diagnosis dapat menjelaskan proses penyakit Sindrom Miller-Fisher. Penulisan ini bertujuan untuk membahas peran pemeriksaan elektrofisiologi dalam diagnosis Sindrom Miller-Fisher. Hasil studi menunjukkan bahwa abnormalitas amplitude Sensory Nerve Action Potential (SNAP) dan H-reflex secara konsisten terjadi pada Sindrom Miller-Fisher. Abnormalitas amplitudo SNAP akan membaik dengan cepat dan reversibel sehingga diperlukan juga pemeriksaan elektrofisiologi serial untuk dapat menunjang diagnosis Sindrom Miller-Fisher. Temuan tersebut dapat diperkuat dengan hasil pemeriksaan konduksi saraf motorik, konduksi saraf sensorik dan F-wave yang normal. Kata Kunci: Sindrom Miller-Fisher, Elektrofisiologi, Diagnosis

Case 9

Ulnar nerve lesions are the second most common mononeuropathies encountered in clinical practice. Although the majority of the lesions are due to entrapment/compression of the ulnar nerve around the elbow (at the cubital tunnel or ulnar groove), it is important to consider and exclude distal ulnar nerve lesions at the wrist or palm. This case highlights the clinical and electrodiagnostic findings of ulnar neuropathies at the wrist, including Guyon canal and pisohamate hiatus. It also discusses the electrodiagnostic challenges in distinguishing distal from proximal ulnar nerve lesions. Emphasis is placed on the use of additional studies, such as the dorsal ulnar sensory nerve action potential, first dorsal interosseous recording, inching studies, and palm stimulation, in the accurate diagnosis of ulnar nerve lesions at the wrist.