Table of Contents
- Introduction
- Etiology
- Innervation of the median nerve at the hand
- Table 1: The Median Nerve Motor Distribution
- Figure 1: Superficial muscles of the hand (Palmar view of the left hand)
- Figure 2: The Median Nerve Sensory Distribution
- Pathophysiology
- Figure 3: The Carpal Tunnel Cross Section
- Clinical features
- Mild to Moderate
- Moderate to Severe
- Figure 4: Thenar atrophy
- Diagnostics Evaluation
- Provocative tests
- Figure 5: Phalen’s maneuver illustration
- Figure 6: Tinel’s sign illustration
- Electrophysiological studies
- Differential Diagnosis
- Table 2: Differential diagnosis of Carpal tunnel syndrome
- Management
- Mild to moderate
- Moderate to severe (or fail conservative management)
- Figure 7: Open carpal tunnel release surgery
- Prognosis
- Further Reading
- Bibliography
Primary Category
Neuromuscular
P-Category
Secondary Category
S-Category
Authors:
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
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)
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
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
Further Reading
- Wright, A. R., & Atkinson, R. E. (2019). Carpal Tunnel Syndrome: An Update for the Primary Care Physician. Hawai'i journal of health & social welfare, 78(11 Suppl 2), 6–10.
- Żyluk A. (2020). The role of genetic factors in carpal tunnel syndrome etiology: A review. Advances in clinical and experimental medicine : official organ Wroclaw Medical University, 29(5), 623–628. https://doi.org/10.17219/acem/118846
- LeBlanc, K. E., & Cestia, W. (2011, April 15). Carpal tunnel syndrome. American Family Physician. Retrieved January 2, 2022, from https://www.aafp.org/afp/2011/0415/p952.html#afp20110415p952-b20
- Wipperman, J., & Goerl, K. (2016, December 15). Carpal tunnel syndrome: Diagnosis and management. American Family Physician. Retrieved January 2, 2022, from https://www.aafp.org/afp/2016/1215/p993.html
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/
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Written by
Founder NeuroCare.AI, Practicing Neurologist, sub-specialized in the field of Neurocritical Care, Stroke & Epilepsy