CARPAL TUNNEL SYNDROME

Introduction

Carpal tunnel syndrome (CTS) is a symptomatic compression neuropathy of the median nerve at the level of the wrist and is characterized by pain and aresthesias in the palmar radial aspect of the hand. Symptoms are often worse at night and exacerbated by repetitive and forceful use of the hand. As the syndrome represents a collection of signs and symptoms, no one test absolutely confirms a diagnosis. CTS is the most common compression neuropathy of the upper extremity.

Related Anatomy *

Scaphoid tubercle, trapezium
Hook of the hamate, pisiform
Transverse carpal ligament
Flexor pollicis longus (FPL) tendons
Flexor digitorum sublimis (FDS) tendons
Flexor digitorum profundus (FDP) tendons

* See image below

Pathogenic Factors

Anatomical: decreased size of carpal tunnel or increased contents of canal
Physiological: neuropathies, inflammatory conditions, fluid imbalances, congenital anomalies
Microbiology: fibrous tissue and variable edema with scattered lymphocytes; Schwann cell response, macrophage recruitment, axonal loss/degeneration, myelin stabilization
Position and use of the wrist: repetitive flexion/extension, squeeze/release, torsion, vibration exposure, weight-bearing with wrist extended, immobilization with wrist flexed

Incidence and Related Conditions

~1 million adults in the United States are diagnosed with CTS each year
Women are affected 3 times more than men; pregnancy is associated with an increased risk for CTS
Up to 50% of patients with thumb carpometacarpal (CMC) joint osteoarthritis also have CTS

Differential Diagnosis

Double crush syndrome
Isolated pathology at the cervical spine, brachial plexus, median nerve of forearm
Intrinsic nerve pathology
Multiple sclerosis (MS)
Amyotrophic lateral sclerosis (ALS)
Charcot-Marie-Tooth disease
Syringomyelia
Spinal muscular atrophy (SMA)

Clinical Presentation Photos and Related Diagrams

Compressed median nerve with pseudoneuroma proximally (right) and median nerve branches distally. (Hover over right edge to see more images)
Testing median nerve sensation in long finger and comparing it to ulnar sensation in the little finger.
Dr. John Durkan demonstrating the application of pressure on the interthenar portion of the median nerve during the Durkan test. Image provided by Dr. Durkan.

Pathoanatomy Photos and Related Diagrams

Carpal tunnel anatomy: Carpal bones form the dorsal roof and the sides of the tunnel while the transverse palmar ligament forms the tunnel floor volarly. The tunnel contains nine flexor tendons and the median nerve.

Symptoms

Numbness in the thumb side of the hand (hypesthesia)

Hand pain radiating to fingers or up the forearm and arm

Tingling (paresthesia)

Clumsiness (eg, dropping objects more than usual)

Weakness

Numbness with reading the newspaper or driving

Difficulty buttoning

Night pain

Typical History

Patients will present with symptoms that first appeared in one or both hands at night and then gradually increased to other times of the day. Patients report symptoms such as numbness and tingling in the palm and fingers, especially the thumb, index and middle fingers, which are intermittent and associated with specific activities such as driving, typing, knitting, etc. Patients will report difficulty grasping small objects or performing other manual tasks. In chronic, untreated cases, the muscles at the base of the thumb may have atrophied; some patients are unable to discriminate between hot and cold by touch.

Positive Tests, Exams or Signs

Median Nerve Compression (Durkan's Test)

Muscle Test: Thenars (ABPB, ABPL, OP, FPB)

Phalen Sign

Thenar Muscle Atrophy

Tinel's Sign: Median Nerve

Grip Strength

Work-up Options

Electrophysiological testing - EMG/NCV

Magnetic resonance imaging - MRI with contrast

Images (X-Ray, MRI, etc.)

MRI showing cross section of carpal tunnel. 1.Ulnar nerve; 2.Hamate and hook of hamate; 3. Trapezium and trapezoidal ridge; 4. Median nerve; 5. Transverse carpal ligament; 6. Flexor tendons

Treatment Options

Conservative:

For patients with symptoms <1 year, intermittent numbness, normal 2-point discrimination and only minor slowing on NCV:

Splinting
Corticosteroid injections
Non-steroidal anti-inflammatory drugs (NSAIDs)

Operative:

For patients with more severe or constant symptoms, prolonged distal motor and sensory latencies, thenar atrophy or who fail conservative management, surgery is indicated:

Open carpal tunnel release (OCTR)
Mini OCTR with carpascope
Endoscopic carpal tunnel release (ECTR)

Complications

OCTR/mini OCTR: median nerve injury, palmar branch injury, failure to relieve symptoms, infection, persistent atrophy, pillar pain
ECTR: ulnar nerve injury, digital nerve injury, tendon injury, superficial palmar arch injury, median nerve injury, palmar branch injury, infection, failure to relieve symptoms, persistent atrophy, pillar pain
Recurrence occurs in up to 19% of patients after carpal tunnel release

Outcomes

Conservative: effective for providing short-term relief of symptoms
ECTR vs OCTR is associated with faster recovery times (return to work, muscle strength) but also associated with more complications owing to reduced visibility during the procedure
OCTR leads to symptomatic relief, patient satisfaction and return to work in the majority of patients

Video

Carpal Tunnel Exam

Key Educational Points

The carpal bones and the transverse carpal ligament are the components of the carpal tunnel. The bony attachments of the transverse carpal ligament are the ridge of the trapezium, the tuberosity of the scaphoid, the hook of the hamate and the pisiform.
The most common cause of numbness and tingling in the upper extremity is carpal tunnel syndrome.
Carpal Tunnel Syndrome is more common in women and often associated with thumb CMC joint arthritis, trigger fingers and DeQuervain'stenosynovitis.
The carpal tunnel compression test (Durkan's Test) is the most sensitive and specific physical exam test for diagnosing Carpal Tunnel Syndrome.
Carpal Tunnel Syndrome can accurately be diagnosed by history and physical exam but the diagnosis is usually confirmed by EMG/NCV testing. EMG/NCV also helps categorize the entrapment as mild, moderate or severe. In mild CTS there is a prolonged sensory latency with normal muscle latency and NO axon loss. In Moderate CTS, both the sensory and motor latencies are prolonged with NO axon loss. In Severe CTS both sensory and motor latencies are prolonged with AXON LOSS.⁵

Practice and CME

References

New articles

Cagle PJ Jr, Reams M, Agel J, Bohn D. An Outcomes Protocol for Carpal Tunnel Release: A Comparison of Outcomes in Patients With and Without Medical Comorbidities. J Hand Surg Am 2014 ePub.
Lane LB, Starecki M, Olson A, Kohn N. Carpal Tunnel Syndrome Diagnosis and Treatment: A Survey of Members of the American Society for Surgery of the Hand. J Hand Surg Am 2014 ePub.
Pacek CA et al. The morphology of the carpal tunnel. Hand (NY). 2010 Jan: 5(2): 135-140. PMCID: PMC2880678
Robert M. Szabo, et al. The Value of Diagnostic Testing in Carpal Tunnel Syndrome. J Hand Surg 1999: 24A:704-714.
Werner RA and Andary M. Electrodiagnostic Evaluation of Carpal Tunnel syndrome. Muscle Nerve 44: 597-607, 2011.

Reviews

Ghasemi-Rad M, Nosair E, Vegh A, et al. A handy review of carpal tunnel syndrome: From anatomy to diagnosis and treatment. World J Radiol 2014;6(6):284-300.
Kim PT, Lee HJ, Kim TG, Jeon IH. Current Approaches for Carpal Tunnel Syndrome. Clin Orthop Surg 2014;6(3):253-257.

Classics

Brain WR, Wright AD, Wilkinson M. Spontaneous compression of both median nerves in the carpal tunnel; six cases treated surgically. Lancet 1947;1(6443-6445):277-82.
Phalen GS, Gardner WJ, La Londe AA. Neuropathy of the median nerve due to compression beneath the transverse carpal ligament. J Bone Joint Surg Am 1950;32(1):109-12.