Patterns of median nerve branching in the cubital fossa: implications for nerve transfers to restore motor function in a paralyzed upper limb

Biopsy of the anterior interosseous motor branch for the pronator quadratus muscle: a safe and minimally invasive diagnostic tool for peripheral neuropathies. Anatomical surgery and surgical technique

BACKGROUND AND OBJECTIVES

Choosing the correct site for a nerve biopsy remains a challenge due to nerve sacrifice and major donor site complications, such as neuroma, as seen in sural nerve biopsy. Selecting a deeper donor nerve can help in burying nerve stumps in deep soft tissues, preventing neuroma. Moreover, using an expendable, deeply situated motor nerve can aid indiagnosis when a motor neuropathy is suspected. The authors propose using the pronator quadratus (PQ) branch for this purpose, as it is located deep between the bellies of the flexor muscles and the interosseous membrane in the forearm. This branch is expendable since the denervation of the PQ has a negligible effect on forearm pronation, which is primarily sustained by the pronator teres.

METHODS

The surgical approach is the same as the approach for anterior interosseous nerve transfer to the motor component of the ulnar nerve in the distal forearm: access is in the midline in the middle third of the forearm under local anesthesia Blunt dissection is performed, separating and retracting the flexor musculotendinous junction to reach the interosseous membrane where the PQ branch is identified. A careful dissection of the nerve branch is performed, allowing a 2 cm long segment to be cut and removed. The proximal stump is then buried into an adjacent muscle belly and the surgical site is closed.

RESULTS

The technique is safe and reproducible in experienced hands.

CONCLUSION

This technique may be especially applicable in cases where neurologists need to study motor neuropathies. Contraindications of the technique include wrist instability and high median nerve palsies.

Nerve transfers in the forearm: potential use in spastic conditions

PURPOSE

Deformities of the spastic upper limb result frequently from the association of spasticity, muscle contracture and muscle imbalance between strong spastic muscles and weak non-spastic muscles. This study was designed to evaluate the feasibility of combining selective neurectomy of the usual spastic and strong muscles together with transfer of their motor nerves to the usual weak muscles, to improve wrist and fingers motion while decreasing spasticity.

METHODS

Twenty upper limbs from fresh frozen human cadavers were dissected. All motor branches of the radial and median nerve for the forearm muscles were identified. We attempted all possible end-to-end nerve transfers between the usually strong "donor" motor branches, namely FCR and PT, and the usually weak "recipient" motor branches (ERCL, ECRB, PIN, AIN).

RESULTS

 The PT had two nerve branches in 80%, thus allowing selective neurectomy. The proximal PT branch could be anastomosed end-to-end in 45% (AIN) to 85% (ECRL) of cases with the potential recipient branches. The distal PT branch could be anastomosed end to end to all potential recipient nerves. The FCR had a single branch in all cases. End-to-end anastomosis was possible in 90% for the ECRL and in 100% for all other recipient branches, but sacrificed all FCR innervation, ruling out hyperselective neurectomy.

CONCLUSION

 Selective neurectomies can be associated with distal nerve transfers at the forearm level in selected cases. The motor nerve to the PT is the best donor for nerve transfer combined with selective neurectomy, transferred to the ECRL, ECRB, PIN or AIN.