Conditions Affecting the Wrist and/or the Hand

and Steven Maschke4



(3)
University of Wisconsin Department of Orthopedic Surgery, Madison, Wisconsin, USA

(4)
Cleveland Clinic, Department of Orthopedic Surgery, Abu Dhabi, UAE

 



Take-Home Message





  • Median nerve compression is supported by a latency >4.5 s and reduction of amplitude and velocity across the wrist.


  • Loss or presence of sensation in the dorsal ulnar cutaneous nerve distinguishes between proximal or distal compression.


  • Parsonage turner presents with severe pain, variable sensory/motor abnormalities, followed by resolution of pain within weeks. It typically self resolves over 1–2 years.


  • The addition of tenosynovectomy, neurolysis, and transverse carpal ligament lengthening has shown no benefit in carpal tunnel release.


Definitions





  • Compressive neuropathy: Mechanical compression of a peripheral nerve resulting in pathologic alteration to its function.


  • Nerve conduction studies:



    • Latency: Measure of speed of conduction for motor or sensory nerves along the fastest fibers.


    • Conduction Velocity: Measure of rate of conduction across a determined segment of the nerve.


    • Amplitude: Measure of height of action potential. Relates to number of conducting axons.


  • EMG:



    • Insertional activity: Muscle electrical activity upon needle insertion. Positive sharp waves in acute denervation, electrical silence in chronic denervation without reinnervation.


    • Fibrillation potentials: Earliest sign of denervation. Most sensitive indicator of nerve compression.


    • Motor unit potentials: Generated by voluntary muscle contraction



      • Decreased motor unit recruitment or activation denotes denervation.


  • EMG/NCS limitations



    • Does not test small or unmyelinated nerve fibers, i.e., pain and temperature.


    • Latency examines fastest conducting fibers only. Normal latency can be present with many but not all of the nerve fibers affected.


    • May be normal up to 6 weeks following complete nerve injury.


Etiology





  • Median nerve:



    • Proximal to distal: Ligament of Struthers. between two heads of pronator teres, FDS, compression from accessory muscle (Gantzer’s) described but rare.


    • Carpal Tunnel:



      • Edematous state, i.e., pregnancy, renal disease, decreased tunnel volume with flexor tenosynovitis, posttraumatic hematoma. Work-related etiologies debated.


      • Rare: Hereditary neuropathies, i.e., CMT and HNPP.


      • Pronator syndrome:



        • Compression of median nerve in the forearm presenting as isolated sensory symptoms.


        • Compression due to pronator teres, under ligament of Struthers, FDS origin.


        • Resisted forearm pronation, long finger flexion, or elbow flexion can reproduce symptoms.


      • AIN Syndrome:



        • Compressive or unprompted loss of AIN function presenting as loss of FPL and index finger FDP function.


      • Parsonage-Turner syndrome: Brachial plexus neuritis typically progresses from several weeks of severe pain to loss of motor function. Isolated AIN palsy is common.


  • Ulnar nerve:



    • Differential for intrinsic atrophy: Cervical root compression, motor neuron disease, i.e., amyotrophic lateral sclerosis and Guillain-Barre



      • Compression at elbow:



        • Flexion decreases space in the cubital tunnel and increases interneural pressure


        • Motor conduction velocity <50 m/s across the elbow diagnostic


        • Multiple sites of compression: Medial head of tricep, medial intermuscular septum, arcade of Struthers, cubital tunnel, between heads of FCU


      • Guyon’s canal:



        • Zone 1: Commonly ganglion cyst


        • Zone 2: Ganglion cyst or hook of hamate fracture


        • Zone 3: Ulnar artery thrombosis


  • Radial Nerve:



    • Wartenburg’s syndrome: Superficial radial nerve compression as its transitions volar to dorsal between ECRL and BR muscles.



      • Etiology: Compressive accessories (wrist watch), repeated supination/pronation activities, localized inflammation (DeQuervein’s).


      • Examination: Decreased sensation dorsal thumb, index finger, first dorsal web space. Positive Tinel’s, reproduction of symptoms with ulnar deviation.


    • Radial Tunnel: Formed laterally by BR and ECRL, medially by bicep and brachialis, and posteriorly by the capsule of the radiocapitellar joint.



      • Clinical diagnosis, pain with palpation over tunnel, concomitant lateral epicondylitis common. Typically no electrodiagnostic findings.


    • Posterior interosseous nerve: Compression due to elbow synovitis (RA), mass, iatrogenic injury with bicep tendon repair.



      • Clinically presents as loss of extensor function with ECRL and BR maintained. That is, attempted wrist extension results in radial deviation.


Pathophysiology





  • Nerve compression:



    • Acute changes due to compression related to transient ischemia.


    • Superficial nerve fibers affected first followed by deeper fibers.


    • Nerve topography dictates progression of symptoms (sensory vs. motor).


    • Progression in chronic compression:



      • Compression → restricted circulation, → neural edema, → perineural fibrosis, → demyelination, → axonal degeneration.


Radiographs





  • AP and lateral X-rays of the wrist may demonstrate bony abnormality.


  • AP and lateral X-rays of the elbow may demonstrate a supracondylar process, medial humeral condyle osteophytes, signs of RA.


Classification





  • Seddon classification:



    • Neuropraxia: Disruption of myelin.


    • Axonotmesis: Axonal disruption with variable retention of connective tissue elements.


    • Neurotmesis: Disruption of entire nerve.


  • Sutherland classification:



    • Further classification of axonotmesis into three distinct types based on increasing damage to connective tissue elements. Questionable clinical relevance.


  • Guyon’s canal zones:



    • Zone 1: Proximal aspect of canal. Mixed sensory and motor nerve compressions.


    • Zone 2: Distal radial aspect of canal. Deep motor branch compression.


    • Zone 3: Distal ulnar aspect of canal. Sensory branch compression.


Treatment





  • NCS/EMG limitations



    • Does not test small or unmyelinated nerve fibers, i.e., pain and temperature.


    • Latency examines fastest conducting fibers only. Normal latency can be present with many, but not all of the nerve fibers affected.


    • May be normal up to 6 weeks following complete nerve injury.


  • Nonoperative:



    • Carpal tunnel: Night time neutral wrist splints, corticosteroid injections proven short-term benefit and prediction of response to surgery


    • Cubital tunnel: Activity modification, elbow pad and splints preventing full flexion and decreasing further nerve trauma or compression, nerve glides, and FCU stretching


    • Wartenberg’s: Limitation of supination/pronation activities, avoidance of compression, corticosteroid injections


    • Guyon’s canal compression: Avoidance of compression


    • Parsonage-Turner syndrome: Supportive treatment. Self-resolving


  • Operative:



    • Carpal tunnel: Carpal tunnel release. No difference with addition of tenosynovectomy, neurolysis, or lengthening of transverse carpal ligament.


    • Cubital tunnel: Cubital tunnel release in situ is gold standard.


    • Transposition only for nerve subluxation (instability) or failed in situ release. May resect a portion of medial head of triceps if needed.


    • Wartenburg’s: Radial sensory nerve decompression between ECRL and BR tendons.


    • Guyon’s canal: Decompression with removal of offending agent. That is, aneurysm excision, pisiform excision, ganglion excision, and hook of hamate excision.


    • PIN: Decompression, rare and debated.


Complications





  • Iatrogenic nerve injury and incomplete recovery with all nerves



Bibliography

1.

Andersen JH, Thomsen JF, Overgaard E, Lassen CF, Brandt LPA, Vilstrup I, Kryger AI, Mikkelsen S. Computer use and carpal tunnel syndrome: a 1-year follow-up study. JAMA. 2003;289:2963–9. doi:10.​1001/​jama.​289.​22.​2963.

 

2.

Cranford CS, Ho JY, Kalainov DM, Hartigan BJ. Carpal tunnel syndrome. J Am Acad Orthop Surg. 2007;15:537–48.

 

3.

Elhassan B, Steinmann SP. Entrapment neuropathy of the ulnar nerve. J Am Acad Orthop Surg. 2007;15:672–81.

 

4.

Lubahn JD, Cermak MB. Uncommon nerve compression syndromes of the upper extremity. J Am Acad Orthop Surg. 1998;6:378–86.

 

5.

Shum C, Parisien M, Strauch RJ, Rosenwasser MP. The role of flexor tenosynovectomy in the operative treatment of carpal tunnel syndrome. J Bone Joint Surg Am. 2002;84-A:221–5.

 



2 Tumors



Abhishek Julka5  and Steven Maschke6


(5)
University of Wisconsin Department of Orthopedic Surgery, Madison, Wisconsin, USA

(6)
Cleveland Clinic, Department of Orthopedic Surgery, Abu Dhabi, UAE

 


Take-Home Message



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Sep 18, 2016 | Posted by in ORTHOPEDIC | Comments Off on Conditions Affecting the Wrist and/or the Hand

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