Not Your Average Median Nerve Injuries

We know all about carpal tunnel syndrome, the most common median nerve injury as discussed in previous Ascend Hand Therapy blog posts. But let's look at the bigger picture of median nerve injuries and how to treat them.
When looking at nerve injuries, type of injury and severity are important in determining prognosis and potential for nerve healing. Nerve injuries can occur from any of the following:

- Stretching or pulling of the nerve, temporary blood flow loss or compression of the nerve, electricity, puncture from an injection, radiation, laceration or even amputation

Further from injury type, severity of injury will also play a large role; level of severity has been identified by the Sunderland classification system:

Chronic vs acute injury
Acute injuries define nerve injuries which occur on a short term, or immediate basis comparable to a chronic injury which is defined as occurring over weeks, months or years. Understanding the difference in an acute nerve injury versus a longer-term chronic injury will also contribute to prognosis after a nerve injury.

Nerve healing rate
Now that we know types, severity and time length of nerve injuries, let’s discuss healing rate of nerves. Nerves heal at a very slow rate, first reinnervation of the nerve and reflex activity must be established, which takes roughly 3 to 4 weeks. (Think of it as 1mm/day; 1inch/month). This tells us, the further away a nerve injury is, and the more severity; the longer for healing and recovery. Furthermore, reinnervation of sensation occurs as a return of pain sensation, then temperature (hot and cold), then differentiating touch and vibration.

Understanding the Median Nerve
The median nerve begins at the brachial plexus, specifically the lateral and medial cords which arise from the cervical spinal cord roots of C5, C6, C7, C8 and T1. Beginning from the cervical spine (neck), traveling the length of the arm into the hand. The median nerve innervates motor and sensory nerves of the following muscles:
- Pronator teres, flexor carpi radialis, palmaris longus, radial flexor digitorum superficialis’, radial flexor digitorum profundus’, flexor pollicis longus, pronator quadratus, abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and the first and second lumbricals

Common Median nerve injuries
Aside from the most common upper extremity nerve compression, carpal tunnel syndrome, there are several additional median nerve injuries:

- Pronator Syndrome: compression of the median nerve as it passes along the elbow joint into the forearm compartment between the two heads of pronator teres. Often a result of recurrent, forceful gripping, forearm rotation or elbow flexion. Most commonly resolved with conservative hand therapy to decompression the nerve, address inflammation and sensory deficits.

- AIN Palsy: compression of the anterior interosseous branch of the median nerve which is the last motor branch of the median nerve into the forearm compartment. Commonly identified by the inability to form the “OK” sign. AIN palsy is associated with a loss of motor control to the thumb, index and middle fingers. AIN palsy is most often treated with hand therapy services, rarely requiring surgical intervention.

- Carpal Tunnel Syndrome: compression of the median nerve at the carpal tunnel. Commonly seen in professions utilizing significant computer work, repetitive or forceful gripping or manual labor. Addressed with hand therapy services, steroid injections or surgical release of the flexor retinaculum (transverse carpal ligament)

Hand specialists at Ascend Hand Therapy know and understand the intricacies of median nerve injuries, anatomy and skilled treatment methods for not only conservative (pre-operative or hoping to avoid surgery) interventions as well as post operative care; utilizing therapeutic modalities, manual techniques and therapeutic exercises to achieve patient-centered goals.

References
https://expertconsult.inkling.com/read/skirven-rehabilitation-hand-upper-extremity-7e/chapter-41/presentation-of-specific-nerve

Median Nerve | Rehabilitation of the Hand and Upper Extremity (inkling.com)

Median nerve - Anatomy - Orthobullets

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