Median Nerve Injury and Carpal Tunnel Syndrome

Median Nerve Injury and Carpal Tunnel Syndrome

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  BY Dr. VEERABHISHEK GOUD MS ORTHO
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  DEFINITION Carpal tunnel syndromeis a nerve disorder of the hand resulting due to compression of the median nerve within the carpal tunnel. Entrapment neuropathy Tardy median nerve palsy
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  ANATOMY-CARPAL TUNNEL  Dorsally- Transverse arch of the carpal bones.  Medially- Hook of the hamate, triquetrum, & pisiform.  Laterally- Scaphoid, trapezium, & fibro-osseous flexor carpi radialis sheath.  Roof- Flexor retinaculum.  Contents – median nerve(most ventral structure) & the nine flexor tendons of the fingers & the thumb.
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  FLEXOR RETINACULUM Proximally –deep forearm fascia Distally –aponeurosis b/w the thenar & hypothenar muscles Over the wrist- the transverse carpal ligament
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  MEDIAN NERVE  Root-C5,6,7,8 and T1.  Along with the ulnar artery passes beneath fibrous arch of flexor digitorum superficialis and runs deep to this muscle on the surface of flexor digitorum profundus.  About 5 cm above flexor retinaculum it becomes superficial and lies between tendons of flexor carpi radialis and flexor digitorum superficialis.  Median nerve enters the palm by passing deep to flexor retinaculum (through carpal tunnel).
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  MEDIAN NERVE  Muscularbranches to all superficial flexors except flexor carpi ulnaris.  Ant interosseus branch – flexor pollicis longus, lat half of flexor digitorum profundus and pronator quadratus. Also supplies distal radioulnar and wrist joints.  Palmar cutaneous branch – skin over thenar eminence, central part of the palm.
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  In the hand: Dividesinto lateral and medial branches Lateral division- Muscular branch to the thenar muscles Three digital branches, 2 for the thumb and one for the lateral side of the index finger which also supplies the 1st lumbrical. Medial division- Digital branches for the second and third interdigital clefts, the latter also supplies the 2nd lumbrical. MEDIAN NERVE
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  MUSCLES EXAMINED: FLEXOR POLLICISLONGUS:
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  OCHSNERS CLASPING TEST:
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  FLEXOR CARI RADIALIS
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  MUSCLES OF THENAREMINENCE: PEN TEST: OPPONENS POLLICIS:  Brings the tip of the thumb towards tip of the other fingers.  Count the fingers.
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  Carpal Tunnel Syndrome
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  PATHOLOGY • Results FromConduction Block In Medial Nerve. • Both Ischemia And Mechanical Block Have Been Implicated. • Initial Lesion Is Intra Funicular Anoxia. • Due To Venous Obstruction From Pressure.
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  FACTORS INVOLVED INTHE PATHOGENESIS OF CARPAL TUNNEL SYNDROME Anatomy: Decrease in Size of Carpal Tunnel  Bony abnormalities of the carpal bones  Acromegaly  Flexion or extension of wrist
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  Increase in Contentsof Canal  Forearm and wrist fractures (Colles fracture, scaphoid fracture)  Dislocations and subluxations (scaphoid rotary subluxation, lunate volar dislocation) Posttraumatic arthritis (osteophytes)  Musculotendinous variants  Aberrant muscles (lumbrical, palmaris longus, palmaris profundus)  Local tumors (neuroma, lipoma, multiple myeloma, ganglion cysts)  Persistent medial artery (thrombosed or patent)  Hypertrophic synovium  Hematoma (hemophilia, anticoagulation therapy, trauma)
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  Neuropathic Conditions  Diabetesmellitus, Alcoholism  Double-crush syndrome  Exposure to industrial solvents
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  Inflammatory Conditions  Rheumatoidarthritis  Gout  Nonspecific tenosynovitis  Infection
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  Alterations of FluidBalance  Pregnancy  Menopause  Eclampsia  Thyroid disorders (especially hypothyroidism)  Renal failure  Long-term hemodialysis
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   Raynaud disease Obesity  Lupus erythematosus  Scleroderma  Amyloidosis  Paget disease
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  CLINICAL FEATURES  Symptoms: Tingling or numbness in part of the hand, relieved by shaking hand repeatedly.  Sharp pains that shoot from the wrist up the arm, especially at night.  Burning sensations in the fingers.  Morning stiffness or cramping of hands  Thumb weakness.  Frequent dropping of objects.  Inability to make a fist.  Shiny, dry skin on the hand.
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  Signs:  Tests forNerve compression  Phalen maneuver
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  Percussion test (Tinelsign)
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  Carpal tunnel compressiontest (Durkan)
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  Static 2-point discrimination Determineminimal separation of two distinct points when applied to palmar finger tip  Failure to determine separation of at least 5 mm
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  Semmes Weinstein monofilaments- Monofilaments of increasing diameter touched to palmar side of digit until patient can determine which digit is touched
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  Electromyography (EMG)  Needleelectrodes placed in muscle  Fibrillation potentials, sharp waves, increased insertional activity
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  Thenar muscles atrophy
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  DIFFERENTIAL DIAGNOSIS:  Tendonitis Tenosynovitis  Nerve compression by cervical disc herniation  Thoracic outlet syndrome
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  IMAGING STUDIES X-ray andMRI  X-ray: check for arthritis or fractured bones; not useful for detecting CTS  MRI: to estimate severity of CTS: not used routinely but is capable of detecting abnormalities indicative of CTS.  CT scan- Displays bony structures but not soft tissues properly  Ultrasonography – shows movement of flexor tendon but not soft tissues
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  NERVE CONDUCTION TEST 90% sensitive & 60% specific  Median nerve stimulated just proximal to the wrist & the start of muscle AP in abductor pollicis brevis is noted  Sensory nerve fiber conduction velocity b/w finger & the wrist is more sensitive .  Criteria – prolonged conduction velocity, increased duration of AP  Criteria – motor latency >4.5 ms and sensory latency >3.5 ms  Surface electrodes on hand and wrist  Small elec. shocks applied to nerves in fingers, wrist, and forearm (measure speed of conduction)
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  TREATMENT Gelberman divided into4 stages –  Early  Intermediate  Advanced  Acute
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  Early stage (mildsymptoms, no thenar atrophy) – steroid injection into the carpal tunnel, splinting. TREATMENT
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   Injection ofcortisone preparations into the carpal tunnel may provide temporary relief, Care should be taken not to inject directly into the nerve. Injection also can be used as a diagnostic tool in patients without osteophytes or tumors in the canal. Most of these cases are probably caused by a nonspecific synovial edema, and these seem to respond more favorably to injection.
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  Conservative  Rest, Ice,Heat  Brace  Drugs  NSAIDS (Ibuprofen Naproxen, Aspirin): Recommended EARLY In The Inflammation Cycle  Corticosteroids : Decrease In Tendon Strength & Mass Over Time
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   Intermediate &the advanced stage – carpal tunnel release.  Acute stage- seen in Cole's # with flexed wrist immobilization – relieved by the change in wrist position / if symptoms still persisting then division of transverse carpal ligament.
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  SURGERY Open technique  Limitedapproach – Double incision of Wilson & the minimal incision of Bromley Endoscopic release –  Agee’s single portal &  the Chow’s two portal technique
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  OCTR ECTR LIT Prox1 portal 2 portal Agee Chow Bromley 1 incis. Carpal tunnel release - techniques
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  OPEN TECHNIQUE  Curvedincision ulnar to & paralleling the thenar crease  Extending proximally to the flexor crease of the wrist  Angle the incision towards the ulnar side of the wrist to avoid palmar sensory branch of median nerve
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  Classical incision
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  Procedure  Dissect proximallyidentify deep fascia of forearm, incise avoiding median nerve beneath.  Divide transverse carpal ligament along its ulnar border to avoid damage to the median nerve.  Release all components of the flexor retinaculum.  Avoid injury to the palmar arterial arch which is 5 to 8 cms distal to the distal margin of the transverse carpal ligament.  Only skin closure.
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  WILSON’S DOUBLE INCISION Transverse incision proximal to the ant wrist crease b/w FCU & FCR tendon  Distal longitudinal incision b/w proximal palmar crease & 1 cm distal to hamate hook in line with radial border of ring finger
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  POSTOP TREATMENT  Compressiondressing  Volar splint- 2 weeks  Immediate hand & finger movements  Suture removal – after 10-14 days  Light daily activities- 2 to 3 weeks  Gradual initiation of strenuous activities- next 4 to 6 weeks
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  ENDOSCOPIC RELEASE Advantages Small incision Single suture Fastrehabilitation Better cosmetic result
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  Disadvantages  Technically demanding Limited visual field  Vulnerability of the median nerve, flexor tendons & superficial palmar arterial arch  Inability to control bleeding
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  Contraindications for ECTR Patient who requires additional procedure- neurolysis, tenosynovectomy.  Space occupying lesion.  Localized infection or hand edema.  Recurrent carpal tunnel syndrome.  Anatomical variations in the median nerve.  Scarred tunnel due to previous tendon surgery or flexor injury.
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  AGEE’S TECHNIQUE Single portal: Incisionover the proximal wrist flexion crease between the tendons of flexor carpi ulnaris and flexor carpi radialis.
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  CHOW’S TECHNIQUE
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  RECURRENT CARPAL TUNNELSYNDROME  Good results seen in 50%  Fair results in 1/3rd  Complications and failures between 3% and 19%  Symptoms may lead to reoperation in 12%
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  RECURRENCE-FACTORS  Incomplete releaseof transverse carpal ligament  Reformation of flexor retinaculum  Scarring in the carpal tunnel  Recurrent tenosynovitis
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  TREATMENT OF RECURRENCE Incomplete ligament release- re-explore & re-release of ligament  Excision and release of flexor retinaculum  For fibrosis or painful scar-epineurolysis, local muscle flaps, free fat grafts  Excision & Z plasty of painful scar  Recurrent tenosynovitis- tenosynovectomy, appropriate medical management