Aravinda K. Therimadasamy

Sonography as an aid to neurophysiological studies in diagnosing tarsal tunnel syndrome.

Diagnosing tarsal tunnel syndrome can be difficult because of varying clinical diagnostic criteria and equivocal physical signs. We present a case of tarsal tunnel syndrome where nerve conduction identified distal tibial neuropathy and high-resolution sonography was able to show nerve swelling within the tarsal tunnel.

Can studies of the second lumbrical interossei and its premotor potential reduce the number of tests for carpal tunnel syndrome

The second lumbrical interossei latency difference test (2‐LINT) is a frequently used test for diagnosing carpal tunnel syndrome (CTS). Recently, the premotor potential (2‐LUMP) observed with 2‐LINT was identified as a median sensory potential. 2‐LINT recording therefore not only compares conduction across equidistant median and ulnar motor segments, but also registers median sensory conduction. In 52 CTS and 50 control hands, we tested whether motor and sensory data obtained with 2‐LINT help to reduce the number of tests necessary to diagnose CTS. The combined sensitivity of 2‐LINT derived parameters (2‐LUMP latency, median second lumbrical to ulnar interossei latency difference, ulnar digit 5 sensory to 2‐LUMP velocity, and ulnar interossei to 2‐LUMP latency difference) was 89%, identical to that of combined non–2‐LINT derived parameters (median digit 3 sensory velocity, ulnar digit 5 to median digit 3 sensory velocity difference, median abductor pollices brevis [APB] latency, median APB to ulnar abductor digiti minimi latency). The 2‐LINT technique with its premotor potential may therefore help to reduce the number of nerve conduction tests commonly needed to investigate patients with suspected CTS. Muscle Nerve, 2007

Nerve ultrasound in electrophysiologically verified Tarsal Tunnel Syndrome

Introduction: Tarsal tunnel syndrome (TTS) arises from tibial nerve damage under the flexor retinaculum of the fibro‐osseus tunnel at the medial malleolus. It is notoriously difficult to diagnose, as many other foot pathologies result in a similar clinical picture. We examined the additional value of nerve ultrasound in patients with tarsal tunnel syndrome confirmed by nerve conduction. Methods: We performed a retrospective analysis of nerve ultrasound changes in electrophysiologically confirmed TTS spanning our records from 2007 to 2015. Results: Nine feet with TTS were identified, all of which showed abnormal nerve ultrasound findings, which in 6 feet, led to identification of the underlying cause. Conclusions: This study shows that nerve ultrasound is abnormal in all cases of electrophysiologically verified TTS. The pattern of nerve abnormality is varied. This, and the fact that in the majority of patients causation was identified, suggests nerve ultrasound should form part of standard work‐up for TTS. Muscle Nerve 53: 906–912, 2016

Limb Hypothermia for Preventing Paclitaxel-Induced Peripheral Neuropathy in Breast Cancer Patients: A Pilot Study

Background Peripheral neuropathy (PN) due to paclitaxel is a common dose-limiting toxicity with no effective prevention or treatment. We hypothesize that continuous-flow limb hypothermia can reduce paclitaxel-induced PN. Patients and methods An internally controlled pilot trial was conducted to investigate the neuroprotective effect of continuous-flow limb hypothermia in breast cancer patients receiving weekly paclitaxel. Patients underwent limb hypothermia of one limb for a duration of 3 h with every paclitaxel infusion, with the contralateral limb used as control. PN was primarily assessed using nerve conduction studies (NCSs) before the start of chemotherapy, and after 1, 3, and 6 months. Skin temperature and tolerability to hypothermia were monitored using validated scores. Results Twenty patients underwent a total of 218 cycles of continuous-flow limb hypothermia at a coolant temperature of 22°C. Continuous-flow limb hypothermia achieved mean skin temperature reduction of 1.5 ± 0.7°C and was well tolerated, with no premature termination of cooling due to intolerance. Grade 3 PN occurred in 2 patients (10%), grade 2 in 2 (10%), and grade 1 in 12 (60%). Significant correlation was observed between amount of skin cooling and motor nerve amplitude preservation at 6 months (p < 0.0005). Sensory velocity and amplitude in the cooled limbs were less preserved than in the control limbs, but the difference did not attain statistical significance. One patient with a history of diabetes mellitus had significant preservation of compound muscle action potential in the cooled limb on NCS analysis. Conclusion This study suggests that continuous limb hypothermia accompanying paclitaxel infusion may reduce paclitaxel-induced PN and have therapeutic potential in select patients and warrants further investigation. The method is safe and well tolerated.

High-Resolution Ultrasonography for Peripheral Nerve Diagnostics: A Guide for Clinicians Involved in Diagnosis and Management of Peripheral Nerve Disorders

The book begins by describing the characteristics of normal and diseased peripheral nerves, and then discusses the value of sonography in common conditions, with the help of clear and easy-to-understand illustrations to explain how to proceed to identify structures. The topics covered include common entrapment neuropathies (carpal tunnel syndrome, ulnar neuropathy, radial neuropathy, peroneal neuropathy) and other conditions in which sonography can play a role in diagnosis, such as CIPD, motor neuropathy with multiple conduction blocks, leprosy, and brachial plexus disorders.

Radial nerve torsion

Peripheral nerve torsion is increasingly recognized due to the widespread availability of nerve ultrasound imaging.1,2 A 31-year-old man presented with acute onset complete left wrist drop after prolonged sleeping on his outwardly rotated arm. There was severe conduction block across the spiral groove and nerve ultrasound showed 2 areas with increased diameter (figure 1). On operation, there was radial nerve trunk torsion at the level of the intermuscular septum just distal to the spiral groove (figure 2). Two months after operation there was no improvement of the complete wrist drop.

Clinical Reasoning: A 54-year-old woman with hand dysesthesia Many dimensions to a common problem

A 54-year-old woman with chronic renal failure due to diabetes and on maintenance hemodialysis presented to the Neurodiagnostic Laboratory of our hospital with cramp-like dysesthetic symptoms involving the palms of both her hands. For the past 6 months, she noticed predominantly right-handed numbness which was maximum over the fingertips and worst early in the morning. Massage and hand movements would relieve the early morning symptoms for short periods of time. There was associated mild difficulty in performing fine motor tasks. Medical history revealed 30 years of type II diabetes mellitus, recently needing control with subcutaneous insulin. The latest HbA1C was 6.6%. She was a nonsmoker and did not abuse alcohol. Serum calcium and phosphate were normal and creatinine 700 μmol/L. Clinical examination revealed an arteriovenous (AV) fistula over the left forearm. Upper limb examination showed absent Tinel’s and Phalen’s sign bilaterally. The thenar and hypothenar eminences were preserved in bulk, with power of the abductor pollicis brevis (APB) and abductor digiti minimi normal on both sides. There was mildly reduced perception to superficial touch (using a cotton swab) and vibration (126 Hz tuning fork) over the distal extremities, and deep tendon reflexes were reduced in the lower extremities. ### Questions for consideration: 1. What is the differential diagnosis of upper limb sensory disturbance in a patient with chronic renal failure and diabetes? 2. What investigations would you do? Upper limb sensory disturbance mainly occurring over the palms with some asymmetry in a patient with renal failure and diabetes would first suggest a possible diagnosis of carpal tunnel syndrome (CTS) or cervical radiculopathy. A diagnosis of cervical radiculopathy is unlikely due to the absence of neck pain. A metabolic length-dependent polyneuropathy would be unusual due to the dominant upper limb symptoms, though needs to be considered in view of the mild sensory loss involving the distal lower …

Teaching NeuroImages: Ulnar neuropathy related to a contraceptive subdermal implant

A 51-year-old woman experienced intermittent left hand numbness and weakness over 2 years, with a claw-hand deformity and weakness of finger abduction, adduction, and distal interphalangeal joint flexion of the medial 2 fingers. Wrist flexion produced hand radial deviation. Palmar and dorsal aspects of digits IV (medially) and V, including medial forearm, had decreased pinprick sensation. Nerve conduction studies showed conduction block 14 cm above the medial epicondyle (figure 1), where Tinel sign was positive. Sonography (figure 2) revealed a hyperechogenic structure distorting the ulnar nerve. The patient had a surgically implanted subdermal contraceptive 10 years prior, causing a rare occurrence of neuropathy.1,2