Carpal Tunnel Syndrome

Primary Category

Neuromuscular

P-Category

Secondary Category

S-Category

Authors:

Bao Quoc Nguyen MD,
Junaid Kalia MD

Introduction

Carpal tunnel syndrome (CTS) is a peripheral neuropathy caused by compression of the median nerve as it passes under the transverse carpal ligament at the wrist.

Symptoms consist of pain, numbness, and tingling; mostly in the hand

Treatment includes non-surgical and surgical management

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Most common entrapment neuropathy. Covers up to 90% of all neuropathies

Etiology

Previous wrist fracture

Occupational factor

Exposure to hand-transmitted vibration
Repeated and forceful activities of the wrist

Pregnancy

Rheumatoid arthritis

Osteoarthritis

Obesity

Diabetes

Other systemic disorders

Systemic amyloidosis
Hypothyroidism
Acromegaly

Innervation of the median nerve at the hand

Table 1: The Median Nerve Motor Distribution

ㅤ	Muscle	Function
Thenar muscles	Abductor pollicis brevis	Thumb abduction
ㅤ	Opponens pollicis	Thumb opposition
ㅤ	Flexor pollicis brevis (superficial head)	Thumb flexion
Intrinsic muscles	Lumbricals I-II	MCP flexion at the joint
ㅤ	ㅤ	PIP and DIP extension

MCP: MetaCarpoPhalangeal ; PIP: Proximal InterPhalangeal; DIP: Distal InterPhalangeal

Figure 1: Superficial muscles of the hand (Palmar view of the left hand)

CFCF. (2015, October 14). English: Based off: Wikimedia Commons. https://commons.wikimedia.org/wiki/File:1121_Intrinsic_Muscles_of_the_Hand_Superficial_sin.png ‌

Figure 2: The Median Nerve Sensory Distribution

Pathophysiology

The carpal tunnel is a narrow osteofibrous outlet, lying between the transverse carpal ligament and the carpal bones, which contains flexor tendons and the median nerve

↑ carpal tunnel pressure → compression of components within a confined space, including the median nerve → altering in the median nerve’s microvascular structure → ↓ endoneurial blood flow → edema and hypoxia → axonal degeneration

Figure 3: The Carpal Tunnel Cross Section

Clinical features

Mild to Moderate

Symptoms progress within the distribution of the median nerve, including the palmar aspect of the thumb, index, middle fingers, and radial half of the ring finger

Pain
Numbness/tingling/burning sensation

Worsen at night or after repetitive motions

Positive Flick sign

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The palmar branch arises from the median nerve ABOVE the wrist level → NO sensory loss in the thenar eminence

Moderate to Severe

Symptoms mentioned above, plus motor dysfunction (weakening opponens pollicis, abductor pollicis brevis, and superficial head of the flexor pollicis brevis)

Weakened grip strength → dropping objects
Thenar atrophy → loss thumb opposition

Figure 4: Thenar atrophy

Diagnostics Evaluation

Provocative tests

Phalen’s maneuver

Holds the patient's wrist in full flexion (90°)
Paresthesia occurs or worsens in the median nerve distribution within one minute → positive
Sensitivity: 57%. Specificity: 58%

Figure 5: Phalen’s maneuver illustration

Tinel’s sign

Taps over the carpal tunnel with fingertips or a reflex hammer
Shooting pain and/or numbness/tingling in the median nerve distribution → positive
Sensitivity: 36%. Specificity: 75%

Figure 6: Tinel’s sign illustration

Other tests

Electrophysiological studies

Nerve conduction studies (NCS)

Confirm the diagnosis
Velocity decrease (prolongation of the distal motor and sensory latency)

Electromyography (EMG)

Evaluate the severity
Surgical prognosis

Differential Diagnosis

Table 2: Differential diagnosis of Carpal tunnel syndrome

Conditions	Characteristics
Cervical radiculopathy C6 or C7	Neck pain radiating to the shoulder and the forearm
ㅤ	Weakness of elbow flexion, extension, and arm pronation
ㅤ	Upper extremities hyporeflexia
ㅤ	Positive Spurling test
Median neuropathy above the carpal tunnel	Impaired palmar cutaneous nerve → thenar eminence sensory loss
ㅤ	More proximal median-innervated muscles involvement (thumb flexion, wrist flexion, and arm pronation)
Arthritis	Rheumatoid arthritis, osteoarthritis, or other inflammatory arthropathies
ㅤ	Usually bilateral involvement
ㅤ	Positive Grind test
ㅤ	X-ray findings
ㅤ	Other lab findings
De Quervain tendinopathy	Tenderness at the distal radial styloid
ㅤ	Positive Finkelstein Test
Hereditary neuropathy with liability to pressure palsy (subvariant of Charcot-Marie-Tooth disease)	Autosomal dominant disorder
ㅤ	Nerve entrapment in multiple areas

Management

Mild to moderate

Conservative management

Lifestyle Modification

Avoiding repetitive motions
Using ergonomic devices (ergonomic keyboard, mouse pad, wrist rest)
Using voice recognition and dictation devices

Short-term oral corticosteroids

Prednisone 20 mg daily for the first week; 10 mg daily for the second week
Rapid response
Gradually wanes over 8 weeks after medication is discontinued

Splinting

Neutral and cock-up wrist splints deliver similar symptoms relief outcomes
Over-night splinting alone can reduce symptom severity and improve median nerve conduction velocities
Follow up for 06-08 weeks

Local corticosteroid injection

Bolus injection of 20 mg Triamcinolone acetonide without lidocaine beneath the transverse carpal ligament
In mild cases, a symptoms-free period might be up to one month after the injection
May be used as an adjuvant therapy before surgery
Carry a risk of median nerve injury

Moderate to severe (or fail conservative management)

Open and endoscopic transverse carpal ligament release surgery has been showing equivalent five-year outcomes

Relieves symptoms significantly more than splinting, but not more than local corticosteroid injection

Figure 7: Open carpal tunnel release surgery

Prognosis

If left untreated → Progress over time and can cause permanent median nerve damage

~90% of mild to moderate cases improve with conservative management only

Up to one-third of the patients have recurring symptoms 5 years after surgery

Bibliography

Aboonq M. S. (2015). Pathophysiology of carpal tunnel syndrome. Neurosciences (Riyadh, Saudi Arabia), 20(1), 4–9.

Geoghegan, J. M., Clark, D. I., Bainbridge, L. C., Smith, C., & Hubbard, R. (2004). Risk factors in carpal tunnel syndrome. Journal of hand surgery (Edinburgh, Scotland), 29(4), 315–320. https://doi.org/10.1016/j.jhsb.2004.02.009

Herskovitz, S., Berger, A. R., & Lipton, R. B. (1995). Low-dose, short-term oral prednisone in the treatment of carpal tunnel syndrome. Neurology, 45(10), 1923–1925. https://doi.org/10.1212/wnl.45.10.1923

LeBlanc, K. E., & Cestia, W. (2011). Carpal tunnel syndrome. American family physician, 83(8), 952–958.

Palmer K. T. (2011). Carpal tunnel syndrome: the role of occupational factors. Best practice & research. Clinical rheumatology, 25(1), 15–29. https://doi.org/10.1016/j.berh.2011.01.014

Sevy JO, Varacallo M. Carpal Tunnel Syndrome. [Updated 2021 Sep 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448179/