The authors describe a case of bifid median nerve associated with carpal tunnel syndrome
A 30 year old female patient presented with a twelve month history of burning pain around the right wrist, paresthesia of the first three fingers , difficulties in fine fingers movements. Clinical diagnosis of carpal tunnel syndrome ( CTS ) relies on physical tests ( Phalen’s test ) and on electromyography . The patient underwent Ultrasound examination, performed by a 10 MHz transducer , of the carpal tunnel which demonstrated on axial scans the presence of two close oval formations with a fascicular hypoechoic structure. This echotexture structurally was similar to nervous tissue and consistent with early bifurcation of the median nerve. The single median nerve was clearly identified in the distal forearm and subsequently splitted. MR Spin - Echo T1 and T2 weighted axial scans confirmed the sonographic findings showing two structures in the normal anatomic site of the median nerve, referred to a bifid median nerve . The signal intensity of the two branches was increased in SE-T2-weighted sequences, presumably indicating a compression-induced edema. No other pathologic findings within the carpal tunnel were detected. The open surgical treatment confirmed the early bifurcation of the nerve inside the carpal tunnel. No other anomalies were found. The patient became symptom free 25 days after surgical treatment.
Carpal tunnel syndrome (CTS) is a neuropathy caused by compression of the median nerve in the carpal tunnel which is secondary to all pathologic conditions determining either reduction in size of the carpal tunnel or increase of the tunnel content. Anatomic variation of the median nerve at wrist which may be associated with carpal tunnel syndrome (CTS). Lanz [1] defined four group of variations found in this nerve in the carpal tunnel: I) variations of the course of the thenar branch; II) accessory branches at the distal portion of the carpal tunnel; III) divided or duplicated median nerve inside the carpal tunnel and IV) accessory branches proximal to the carpal tunnel. Anatomic variant of the median nerve occurred at our attention was represented by early duplication of the median nerve inside the carpal tunnel which corresponds to the III class of Lanz's classification [1]. Group III of Lanz classification is more frequently associated with CTS [1] since the two branches run parallel in the tunnel causing increase of the tunnel content with subsequent compression of the median nerve. It is important for the surgeon to know preoperatively of this anatomic variation for carpal tunnel release. Since the open surgical approach is the treatment of choice the endoscopic release has to be avoid in these case [2-3].
Add median nerve duplication
1. On carpal tunnel region imaging (ultrasound/CT), a bifurcation (i.e., “double” or “duplicated” median nerve) is observed in the proximal segment of the carpal tunnel. Two nerve branches proceed in parallel within the tunnel.
2. Compared to the usual form of the median nerve, the bifurcated nerve overall shows a mildly enlarged cross-sectional area, which could lead to crowding of structures within the carpal tunnel.
3. No obvious bony abnormalities are noted. The tendons and soft tissues around the wrist appear generally intact, though local tendon sheaths may be thickened or show varying degrees of edema.
Based on the patient's history (30-year-old female with clinical presentation suggestive of carpal tunnel syndrome) and the imaging findings, potential diagnoses include:
1. Carpal Tunnel Syndrome (CTS): The presence of a bifid median nerve increases the volume of contents within the carpal tunnel, and in a relatively confined space, this can result in or worsen nerve compression symptoms.
2. Other Compression Neuropathies of the Wrist: Such as those involving the ulnar or radial nerve distal branches; however, given the imaging findings and classic symptoms, these are less likely.
3. Joint or Tendon-related Pathology Increasing Carpal Tunnel Pressure: For instance, tenosynovitis. However, these typically present with pronounced tendon sheath thickening or synovitis on imaging. In this case, the primary feature remains the bifurcated median nerve.
Since the patient’s local symptoms align with typical CTS manifestations and imaging clearly demonstrates a bifurcated median nerve in the carpal tunnel, the most likely diagnosis is carpal tunnel syndrome triggered or exacerbated by this anatomical variation.
Considering the patient’s age, sex, clinical symptoms (related to carpal tunnel syndrome), and imaging findings (suggesting a bifid median nerve increasing the overall volume), the most likely comprehensive diagnosis is:
Carpal Tunnel Syndrome Caused by a Bifid (Duplicated) Median Nerve.
If doubt remains, further evaluation using electromyography (EMG) and nerve conduction velocity (NCV) tests can help assess the functional status of the median nerve. Higher-resolution imaging may be employed if further clarification of nerve or soft tissue structures is required.
1. Conservative Treatment:
• Initial measures include wrist immobilization or use of a splint to reduce pressure in the carpal tunnel and alleviate symptoms.
• If necessary, local injections (e.g., corticosteroids) under professional guidance may be used to reduce inflammation and edema.
2. Surgical Intervention:
• For carpal tunnel syndrome caused by a bifid median nerve, open surgical decompression is considered safer and more feasible. Because of the anatomical variation, direct visualization allows careful separation of the nerve branches to avoid intraoperative injury.
• Endoscopic surgery is generally not recommended due to the complexity added by the bifid nerve, which can increase procedural difficulty and risk.
3. Rehabilitation/Exercise Prescription (FITT-VP Principle):
• Frequency (F): Begin with wrist-focused functional training 3–4 times per week; once symptoms improve, reduce to 2–3 times per week.
• Intensity (I): Start at a low, comfortable level, avoiding movements that provoke pain or numbness. Gradually increase difficulty.
• Time (T): Begin with 10–15 minutes per session, possibly in short segments. Increase to about 20 minutes as tolerance improves.
• Type (T): Under the guidance of a physician or physical therapist, implement exercises such as wrist flexion-extension, median nerve gliding, grip-strength exercises, and gentle upper limb strengthening and flexibility workouts.
• Volume/Progression (VP): Once symptoms show improvement, increase repetition count and duration of exercises. You may also introduce light resistance tools for grip training, but avoid excessive load.
4. Notes:
• Patients who already have indications for surgery or plan to undergo surgery should consult with a specialist before starting or modifying rehabilitation to avoid overuse of the hand prior to or immediately after surgery.
• Maintain proper wrist positioning with splint use and adjust the rehabilitation program under professional supervision.
• If pain intensifies, sensory deficits worsen, or if pain becomes severe at night, seek medical attention promptly.
Disclaimer: This report is an advisory analysis based on the current clinical and imaging data and does not replace in-person consultation or professional medical advice. If you have any concerns, please consult with a specialist for an individualized treatment plan.
Add median nerve duplication
