Carpal Tunnel Syndrome: Comprehensive Overview
Definition and Pathophysiology
Carpal tunnel syndrome (CTS) is a median nerve entrapment neuropathy at the wrist, affecting 4-5% of the population, caused by compression of the median nerve as it travels through the carpal tunnel. 1, 2
- The pathophysiology involves mechanical trauma, increased pressure within the carpal tunnel, and ischemic damage to the median nerve 2
- CTS is the most common peripheral nerve entrapment encountered worldwide and the most frequently reported form of median nerve compression 2, 3
Clinical Presentation
Classic Symptoms
- Numbness and paresthesias along the median nerve distribution (radial 3.5 digits: thumb, index, middle, and radial half of ring finger) 4, 3
- Nocturnal paresthesias and neuritic "pins-and-needles" pain are characteristic 3
- Pain in the hand with tingling in the median nerve distribution 2
- Thenar muscle weakness is a late manifestation indicating advanced disease 4
Risk Factors
- Female gender and elderly age show increased frequency 3
- Obesity 2
- Monotonous wrist activity and repetitive exposure to vibrations or forceful angular motions 2, 3
- Pregnancy 2, 3
- Genetic heredity 2, 3
- Diabetes mellitus 3
- Rheumatoid inflammation 2
Diagnostic Approach
Clinical Diagnosis
The American College of Radiology recommends that CTS be primarily diagnosed through clinical evaluation combined with electrophysiologic studies, with imaging reserved for selected circumstances only. 5
Physical Examination Maneuvers
- Tinel's sign and Phalen's sign are helpful provocative tests in suggesting the diagnosis 4, 3
- These maneuvers can evoke symptoms to guide diagnosis 3
Electrophysiologic Testing
- Electrophysiologic studies (nerve conduction studies and needle electromyography) are recommended to confirm the diagnosis 5, 4
- These tests help determine whether CTS is acute or chronic and identify evidence of axonal injury 3
- Electroneuromyographic examination may be recommended before surgery or in cases of occupational illnesses 6
Important caveat: The American Academy of Neurology recommends against routine laboratory testing for patients with typical CTS, as it may generate more false positives than true positives 5
Imaging Studies
When to Use Imaging
- Ultrasound is highly sensitive and specific for diagnosing CTS when compared with clinical assessment and electrophysiologic studies 5
- Ultrasound can measure the cross-sectional area of the median nerve at various locations and is the validated technique to measure median nerve size 5
- Wrist ultrasound or MRI without contrast may be appropriate in selected circumstances for patients with clinical symptoms and unclear diagnoses 5
- MRI may be used in the diagnosis of atypical cases 4
The American College of Radiology suggests that CT, CT arthrography, bone scan, and radiographic arthrography are not routinely used to diagnose CTS. 5
Laboratory Testing for Atypical Cases
- Consider laboratory tests (HbA1c, TSH, Vitamin B12, Vitamin B6, folic acid, serum protein electrophoresis with immunofixation) to exclude underlying reversible causes of neuropathy in atypical presentations 5
- Additional tests (ANA, ESR, CRP, ANCA, hepatitis B/C serologies, HIV) may be considered when signs suggest systemic diseases 5
Treatment Algorithm
Non-Surgical Management (Mild Cases)
For mild and discontinuous symptoms, non-surgical measures are indicated. 3
- Wrist splinting 2
- Ergonomic maneuvers and change of working position 4, 2
- Use of alternative non-vibrating equipment at work 2
- Steroid injections may alleviate symptoms in mild cases 4
- Medications 2
Surgical Management (Moderate to Severe Cases)
Surgical decompression is the most effective treatment for CTS, providing significantly better symptom relief than non-surgical options, especially for moderate to severe cases. 5
Indications for Surgery
- Severe symptoms 4
- Failure to respond to conservative therapy 4
- Significant evidence of axonal injury on electrophysiologic testing 3
Surgical Techniques
Open carpal tunnel release and endoscopic carpal tunnel release are equally effective for symptom relief, with endoscopic repair allowing patients to return to work approximately one week earlier. 5
- Open carpal tunnel release is the classical surgery with usually excellent results and remains the most common hand surgery procedure 4, 3
- Endoscopic carpal tunnel release was introduced to decrease the morbidity of open surgery, though it has its own complications and is still being refined 4
Post-Surgical Complications and Management
Persistent Symptoms After Surgery
- The American College of Radiology recommends ultrasound evaluation of the median nerve as the first-line imaging study to evaluate persistent numbness and shooting pain after carpal tunnel release 5
- Ultrasound can identify incomplete decompression of the median nerve or post-surgical complications 5
Worsening Symptoms After Surgery
- Complex regional pain syndrome is a rare complication that should be considered in the differential diagnosis 5
- Consider coexisting conditions such as polyneuropathy that may have been masked by CTS symptoms 5
- Evaluate nerve function using electrodiagnostic studies 5
Conservative Post-Surgical Management
Conservative management, including physical therapy focusing on optimal postural alignment, normal movement patterns, and strategies to reduce muscle overactivity, pain, and fatigue, should be considered for 4-6 weeks before proceeding to surgical re-exploration. 5
Critical Pitfalls to Avoid
- Avoiding prolonged immobilization is crucial, as it can lead to muscle deconditioning and potentially worsen symptoms 5
- Patients should gradually increase activity using the affected limb within functional activities 5
- Excessive use of splinting should be avoided, as it may prevent restoration of normal movement and function 5
- Serial casting for fixed functional dystonia has been associated with worsening symptoms 5