Describe the epidemiology.
Most common entrapment neuropathy (90% of all cases) 
The prevalence and yearly incidence of CTS may change according to several occupational and nonoccupational factors.
List risk factors.
CTS is caused by compression of the median nerve in the carpal tunnel, under the transverse carpal ligament. 
Previous fracture of the wrist
Traumatic dislocation of the lunate 
Manual work: increased risk in workers using vibrating tools or prolonged, forceful, and repetitive flexion/extension of the wrist 
Rheumatoid arthritis and other types of chronic inflammation of the tendon sheaths 
Pregnancy and puerperium 
Renal failure and dialysis-associated deposition of amyloid 
Describe the pathophysiology.
The carpal tunnel is a narrow fibro-osseous structure at the level of the palmar aspect of the wrist, delimited by the carpal bones and the transverse carpal ligament, which contains flexor tendons and the median nerve.
Pressure increase within the carpal tunnel → compression of contained structures → impaired blood flow and altered microvascular structure of the median nerve → inflammatory reaction → edema and hypoxia → axonal degeneration
Develop in the areas innervated by the median nerve: palmar surface of the thumb, index, and middle fingers, and radial half of the ring finger.
Paresthesia: burning sensation, tingling
Loss of sensation/numbness
Typically worsen at night
Patients often report that symptoms improve by shaking the hand (flick sign). 
Severely affected patients may report:
Dropping objects and difficulty with fine motor skills (e.g., buttoning up clothing) secondary to weakened finger pinch and grip strength
Disappearance of pain
List examination findings.
Mild disease: Initial examination is often normal; symptoms only develop with provocative tests for CTS.
Severe disease: Findings of both sensory and motor deficits may be seen.
Examination of the sensory system
May show decreased sensation in the area innervated by the median nerve distal to the carpal tunnel
Usually, there is no loss of sensation of the palmar surface of the thenar eminence because it is innervated by the superficial branch of the median nerve, which arises 5–7 cm proximal to the carpal tunnel and is, therefore, not compressed.
Examination of the motor system: may show weakness in thumb abduction and opposition as well as thenar atrophy
Sensory innervation of the thenar eminence is not affected in CTS.
The "pope's blessing" (inability to flex the first three digits when making a fist) is not a symptom of CTS. It is only seen in proximal lesions of the median nerve
List general diagnostic principles.
Usually a clinical diagnosis, based on classic clinical features of CTS combined with positive provocative tests for CTS 
Consider additional testing (e.g., electrodiagnostic studies) in:
Severe cases (e.g., those that may require surgical intervention)
List provocative tests.
Considered positive when sensory symptoms (e.g., pain, paresthesias) are elicited along the distribution of the median nerve distal to the carpal tunnel 
Usually performed in combination as use of a single provocative test has low sensitivity and specificity 
Commonly used provocation tests
Phalen test: The patient's wrist is held in full flexion (90°) for one minute. 
Tinel sign: The examiner percusses or taps with the fingertips over the carpal tunnel.
Hand elevation test: The patient holds both hands above their head for one minute.
Carpal compression test: The examiner uses a finger to apply moderate pressure directly over the carpal tunnel for 30 seconds.
Describe electrophysiological tests.
Diagnostic uncertainty or atypical presentation
To rule out alternative diagnoses (e.g., polyneuropathy, radiculopathy)
Nerve conduction studies (confirmatory test): show impaired median nerve conduction along the carpal tunnel
Prolonged sensory and distal motor latency
May be normal in patients with mild disease
Usually ordered to rule out alternative diagnoses
May show abnormal spontaneous activity (e.g., fibrillation potentials) or altered action potential morphology
Electrodiagnostic studies are not necessary to confirm a clinical diagnosis of CTS but should be ordered when the diagnosis is uncertain and for patients scheduled to have surgery.
Carpometacarpal arthritis of the thumb
Arthritis of the wrist
Cervical radiculopathy (C6)
De Quervain tendinopathy
Vibration white finger
Describe the treatment approach.
Mild to moderate disease
Trial immobilization or glucocorticoid injection.
No response after 6 weeks
Assess for adherence.
Trial alternate conservative methods.
Severe or refractory disease: Refer to a hand specialist for possible surgery.
Describe the conservative management.
Treatment of underlying comorbidities
Immobilization: splinting of the wrist in a neutral position.
First-line: steroid injection, e.g., methylprednisolone
Alternative: oral glucocorticoids, e.g., prednisone
Physical therapy and exercise: e.g., nerve glide exercises, therapeutic ultrasound, and carpal bone mobilization
Oral analgesia (e.g., NSAIDs, gabapentin) is not effective in managing CTS
Describe the surgical treatment.
Indications: severe disease or refractory symptoms
Open or endoscopic release of the transverse carpal ligament
The transverse carpal ligament is divided to increase space for the median nerve in the carpal tunnel.