Carpal Tunnel (CTS) & Ulnar Nerve Neuropathies

Carpal Tunnel Syndrome and Ulnar Neuropathy are the two most common entrapment neuropathies of the upper extremity, frequently occurring together or causing diagnostic confusion.

What is involved?

• Carpal Tunnel Syndrome: Median nerve at the wrist
• Ulnar Neuropathy: Ulnar nerve, most commonly at the elbow

Location

• Median Nerve: Carpal tunnel at the wrist (between carpal bones and transverse carpal ligament)
• Ulnar Nerve: Cubital tunnel at the elbow (behind medial epicondyle) or Guyon’s canal at the wrist

Common symptoms

Carpal Tunnel Syndrome

• Numbness/tingling in thumb, index, middle finger (and radial half of ring finger)
• Hand weakness, dropping objects
• Symptoms worse at night, patient wakes up shaking hands
• May radiate up the forearm
• Usually bilateral but often asymmetric

Ulnar Neuropathy at Elbow

• Numbness/tingling in ring and little fingers
• Hand weakness, difficulty with fine motor tasks
• Symptoms often related to elbow position
• May have elbow soreness
• Wasting of hand intrinsic muscles

Both Together

• When both conditions present, can have numbness in all fingers
• Important to differentiate from cervical radiculopathy or peripheral neuropathy

Onset

• Usually gradual over months to years
• Carpal tunnel may worsen during pregnancy or with fluid retention
• Ulnar neuropathy may follow elbow trauma or prolonged leaning on elbow

Risk factors

Carpal Tunnel

• Female gender
• Diabetes
• Pregnancy
• Hypothyroidism
• Rheumatoid arthritis
• Repetitive hand activities
• Wrist fracture

Ulnar Neuropathy

• Leaning on elbows
• Prolonged elbow flexion
• Prior elbow fracture or trauma
• Diabetes
• Surgery in lateral decubitus position

Exam

Carpal Tunnel Syndrome

• Thenar (APB) atrophy in severe cases
• Weak thumb abduction (APB testing)
• Decreased sensation over median distribution (thumb, index, middle fingers)
• Positive Tinel at wrist (tingling with tapping)
• Positive Phalen test (symptoms with 60 seconds wrist flexion)

Ulnar Neuropathy at Elbow

• Hypothenar atrophy
• First Dorsal Interosseous (FDI) atrophy
• Weak finger abduction and adduction
• Weak finger flexion at DIP of little finger (FDP)
• Decreased sensation over ulnar distribution (little finger, ulnar ring finger)
• Positive Tinel at elbow
• Froment sign (thumb IP flexion with key grip)

Differentiating Features

Feature	Carpal Tunnel	Ulnar Neuropathy
Numb fingers	1, 2, 3	4, 5
Thenar atrophy	Yes	No
Hypothenar atrophy	No	Yes
FDI atrophy	No	Yes
Night symptoms	Prominent	Less common
Tinel location	Wrist	Elbow

EMG

EMG is essential for confirming diagnosis and assessing severity.

Carpal Tunnel Syndrome Findings

• Prolonged median sensory distal latency (>3.5 ms)
• Prolonged median motor distal latency (>4.2 ms)
• Median-ulnar sensory latency difference >0.5 ms
• Low median sensory amplitude
• Normal ulnar studies
• APB denervation on needle EMG in moderate-severe cases

Ulnar Neuropathy at Elbow Findings

• Slowed ulnar motor conduction velocity across elbow (less than 50 m/s)
• Drop in CMAP amplitude across elbow (>20% suggests conduction block)
• Low ulnar sensory amplitude
• Normal median studies
• FDI, ADM, FCU denervation on needle EMG

When Both Are Present

• Abnormalities in both median and ulnar distributions
• Important to check lower extremity nerves to exclude generalized neuropathy
• “Double crush” phenomenon may coexist

Severity Grading

Carpal Tunnel:

• Mild: sensory only prolonged
• Moderate: sensory and motor prolonged
• Severe: absent sensory, motor prolonged, denervation

Ulnar Neuropathy:

• Mild: slowing across elbow only
• Moderate: slowing with sensory amplitude drop
• Severe: conduction block, low amplitudes, denervation

Recommendations

Carpal Tunnel Syndrome

• Mild: Night splints in neutral position, activity modification
• Moderate: Add corticosteroid injection
• Severe: Surgical release (carpal tunnel release), especially with thenar atrophy or denervation

Ulnar Neuropathy at Elbow

• Mild: Elbow padding, avoid leaning on elbow, avoid prolonged flexion
• Moderate: Night splint to prevent elbow flexion
• Severe: Surgical options include simple decompression, medial epicondylectomy, or anterior transposition

When Both Present

• Treat the more symptomatic condition first
• Consider staged surgeries if both require intervention
• Address underlying conditions (diabetes, etc.)

What else could it be?

• Cervical Radiculopathy (C6-C8): neck pain, dermatomal pattern, weakness in multiple muscles
• Peripheral Neuropathy: bilateral, symmetric, affects feet too
• Thoracic Outlet Syndrome: vascular symptoms, affects C8-T1 distribution
• Pronator Syndrome: forearm pain, no night symptoms
• Anterior Interosseous Syndrome: no sensory loss, weakness only
• Guyon’s Canal Syndrome: ulnar neuropathy at wrist, spares dorsal cutaneous branch
• Brachial Plexopathy: affects multiple nerves, abnormal sensory potentials