An Epidermoid Cyst along the Sensory Branch of Digital Nerve with Focal Neuropathy: A Case Report

An epidermoid cyst is a slow-growing benign neoplasm that commonly occurs in the hand. Herein, we report a rare case of an epidermoid cyst with focal neuropathy in the left ring finger of a 38-year-old woman. Preoperatively, the patient complained of erythema, swelling, and paresthesia on her fingertips. On ultrasonography and magnetic resonance imaging, ulnar digital nerve thickening and inflammation around the nerve were observed, and a neurogenic tumor-like schwannoma was expected. An excisional biopsy with neurectomy of the involved sensory branch of the ulnar digital nerve was performed under brachial plexus block. During the operation, there is such an uncommon morphology, yellowish debris under the epineurium of the ulnar digital nerve sensory branch was involved with the epidermoid cyst and seemed to be propagating along the sensory branch from the skin surface. After the operation, the paresthesia and swelling resolved. Over the 6-month follow-up in the outpatient clinic, no complications and recurrences occurred. Thus, we reported a rare intraneural epidermoid cyst (occurred along the digital nerve) in the finger, and we believe that considering the anatomical characteristics and the surrounding structures is important during mass excision.

Focal Neuropathy Mimicking Focal Dystonia in a Child: Diagnostic and Rehabilitative Tools

Object: Focal neuropathy results from an injury of any etiology that occurs in a peripheral nerve. The lesion may be followed by alteration of the sensory sphere (either dysesthesia or paresthesia with or without neuropathic pain), or by compensatory attitudes that are attributable to the altered contraction in muscles that are innervated by the injured nerve. Methods: We describe the case of a 13-year-old boy who attended our hospital for a focal neuropathy of the radial nerve. Conclusion: This neuropathy was revealed after the removal of a plaster Zimmer splint that was applied following a post-traumatic subluxation of the metacarpal-trapezoid joint.

Focal peripheral neuropathy

Some causes of focal peripheral nerve damage are self-evident, such as involvement at sites of trauma, tissue necrosis, infiltration by tumour, or damage by radiotherapy. Focal compressive and entrapment neuropathies are particularly valuable to identify in civilian practice, since recovery may follow relief of the compression. Leprosy is a common global cause of focal neuropathy, which involves prominent loss of pain sensation with secondary acromutilation, and requires early antibiotic treatment. Mononeuritis multiplex due to vasculitis requires prompt diagnosis and immunosuppressive treatment to limit the severity and extent of peripheral nerve damage. Various other medical conditions, both inherited and acquired, can present with focal neuropathy rather than polyneuropathy, the most common of which are diabetes mellitus and hereditary liability to pressure palsies. A purely motor focal presentation should raise the question of multifocal motor neuropathy with conduction block, which usually responds well to high-dose intravenous immunoglobulin infusions.

Carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a compressive focal neuropathy of the median nerve (NM) at the wrist. We hypothesize that reverse Phalen’s test rather than the previously commonly proposed classic Phalen’s maneuver was a logical maneuver in the diagnosis of CTS from the anatomic, pathophysiological and electrophysiological viewpoint. Dorsal flexion of the hand results in an increase in the flexor retinaculum tension (RFT), extension of the finger long flexor muscle tendons and consequential NM entrapment between the tendons and flexor retinaculum (RF). Thus, the carpal tunnel (CT) volume is reduced, the intra-tunnel pressure is increased, while the RF to NM distance is decreased. On Phalen’s maneuver, the forced palmar hand flexion entails opposite consequences i.e. reduced RFT, relaxation of the finger long flexor muscle tendons, decreased pressure upon NM, slight increase in the CT volume, decreased intra-tunnel pressure and increased RF to NM distance. The hypothesis can be tested by a conductive NM study, preferably at three positions: mid-position (palmar/volar angle 180 degrees); forced dorsal flexion (palmar/volar angle about 270 degrees); and forced palmar (volar) flexion (palmar/volar angle about 90 degrees). Relative to mid-position, “deterioration” of electroneurography (ENG) finding is observed in dorsal flexion, whereas “improvement” of ENG finding is recorded in palmar flexion.