Focal Numbness in Left Thumb with Dermatomal Distribution

Case at a Glance

A 27-year-old female presents with acute onset numbness in her left thumb following repetitive hand use in her profession as a nail technician and hair braider.

Patient's Story

The patient is a 27-year-old female who works as a nail technician and hair braider, requiring extensive use of her hands throughout the workday. Despite being right-hand dominant, her work involves bilateral hand usage. She presented with a 2-day history of numbness affecting her left thumb. She described the numbness as having a distinct boundary, creating a clear line of demarcation between the affected and unaffected areas. She experienced a brief episode of paresthesias (pins and needles sensation) near her left wrist, lasting only a few seconds on one occasion. The patient denies any recent trauma, medication use, or systemic symptoms. She maintains an active lifestyle and has no significant past medical history.

Initial Assessment

Physical examination revealed focal numbness limited to the left thumb with a clear dermatomal distribution pattern. The patient was able to demonstrate the precise boundaries of the affected area. No obvious signs of trauma, swelling, or discoloration were noted. The patient appeared otherwise healthy and demonstrated normal function in the remaining digits.

The Diagnostic Journey

Given the patient's occupation involving repetitive hand motions and the specific distribution of symptoms, differential diagnoses included median nerve compression (carpal tunnel syndrome), radial nerve irritation affecting the superficial branch, or focal neuropathy. The dermatomal pattern of numbness and occupational risk factors were key clinical features guiding the diagnostic consideration.

Final Diagnosis

Occupational-related peripheral nerve irritation, likely involving the superficial branch of the radial nerve or early median nerve compression syndrome, secondary to repetitive hand use in professional activities.

Treatment Plan

Conservative management including activity modification, ergonomic workplace adjustments, intermittent rest periods during work, and monitoring for symptom progression. Patient education regarding proper hand positioning and stretching exercises for prevention of repetitive strain injuries.

Outcome and Follow-up

Patient advised to monitor symptoms and return for evaluation if numbness persists beyond one week, spreads to other areas, or is accompanied by weakness or increased pain. Referral for nerve conduction studies to be considered if conservative measures fail to provide improvement.