A. Etiology [1]

1. Trauma
2. External Compression
3. Idiopathic
4. Risk Factors
   1. Diabetes mellitus
   2. Rheumatoid Arthritis
   3. Smoking
   4. EtOH Consumption
   5. Hypothyroidism
   6. AIDS
5. Uncommon Risk Factors
   1. Acromegaly
   2. Amyloidosis
   3. Malnutrition
   4. Pregnancy

B. Carpal Tunnel Syndrome [1,2,3]

1. Most common entrapment condition
2. Median nerve compression at the wrist
3. Decreased pain sensation, numbness in digits 1-3; thenar atrophy
4. May be related to repetitive tasks such as typing, drilling, etc.
5. Signs
   1. Phalen's: Wrist hyperflexion causes tingling in fingers
   2. Tinnel's: Tapping median nerve at wrist causes tingling in fingers
6. Nerve conduction velocity (NCV) on wrist are best test to confirm diagnosis
7. Treatment
   1. Splinting
   2. Non-steroidal anti-inflammatory drugs (NSAIDs)
   3. Glucocorticoid injections
   4. Surgical decompression in severe cases

C. Other Median Nerve Syndromes [4]

1. Pronator Syndrome
   1. Pain in volar forearm with numbness in digits 1-3 and ~50% of 4th
   2. Symptoms similar to Carpal Tunnel syndrome
   3. Tinel's sign positive in forearm
   4. NCS will confirm diagnosis
   5. Splinting elbow in flexion, decreased activity, NSAIDs.
   6. Surgical correction may be required
2. Anterior Interosseous Syndrome
   1. Transient pain in mid-volar forearm
   2. Weakness in thumb-index finger pinch
   3. Weakness of flexor pollicis longus, flexor digitorum profundus, pronator quadratus
   4. NCV study helpful (median nerve distal to elbow)
   5. Decrease activity, splint elbow in flexion

D. Fourth and Fifth Finger Dysesthesia and Weakness

1. Cervical Radiculopathy
2. Thoracic Outlet Syndrome
3. Cubital Tunnel Syndrome - compression of ulnar nerve at elbow
4. Ulnar Tunnel Syndrome - compression of ulnar nerve at wrist

E. Cervical Radiculopathy (Cervical Spondylitis) [6]

1. Dysfunction of cervical spinal nerve, roots of nerve, or both
   1. Incidence of ~1/1000 men, 0.6/1000 women
   2. Peak age 50-54 years, mainly in age >40 years
   3. History of physical exertion or trauma precedes symptoms in only ~15% of cases
2. Causes
   1. Usually caused by cervical disk disease (cervical spondylosis)
   2. Foraminal encroachment in ~70% of cases
   3. Foraminal encroachment due to decreased disc height, degenerative changes in joints
   4. Nucleus pulposus herniation responsible for 20-25% of cases only
   5. Tumors of spine and spinal infections are very uncommon
3. Presentation
   1. Pain in neck and one arm
   2. Combination of sensory loss, loss of motor function, or reflex changes
   3. Pain radiates above shoulder
4. Diagnosis
   1. History and physical exam usually sufficient to make diagnosis
   2. Radiographic testing only indicated if "red flags" are present
   3. C7 is most commonly affected, followed by C6
   4. Physical Exam Findings (Table 1, Ref [6]) are helpful for localizing root compression
5. Disk Level C4-5 (Root C5):
   1. Pain: medial scapular border, lateral upper arm to elbow
   2. Weakness: deltoid, supraspinatus, infraspinatus
   3. Sensory Loss: left upper arm
   4. Reflex Loss: supinator reflex
6. Disk Level C5-6 (Root C6):
   1. Pain: lateral forearm, thumb, index finger
   2. Weakness: biceps, brachioradialis, wrist extensors
   3. Sensory Loss: thumb, index finger
   4. Reflex Loss: biceps reflex
7. Disk Level C6-7 (Root C7):
   1. Pain: medial scapula, posterior arm, dorsal forearm, third finger
   2. Weakness: triceps, wrist flexors, finger extensors
   3. Sensory Loss: posterior forearm, third finger
   4. Reflex Loss: triceps reflex
8. Disk Level C7-T1 (Root C8):
   1. Pain: shoulder, ulnar side of forearm, fifth finger
   2. Weakness: thumb flexors, abductors, intrinsic hand muscles
   3. Sensory Loss: fifth finger
   4. Reflex Loss: none
9. Indications for Radiographic Testing
   1. Include possible red flags
   2. History of fever or chills
   3. Unexplained weight loss
   4. Unremitting night pain
   5. Previous cancer
   6. Immunosuppression
   7. Intravenous drug abuse
   8. Symptoms of myelopathy: diffuse hand numbness, balance difficulty, sphincter dysfunction
   9. Pain lasting >6 weeks
10. Testing
    1. MRI of Cervical Spine - method of choice, but high false positive rates
    2. CT is of limited value in assessing root disease
    3. EMG / NCS only for distinguishing nerve root pain from other causes of neck/arm pain
11. Differential Diagnosis (Table 3, Ref [6])
    1. Peripheral entrapment neuropathies
    2. Disorders of rotator cuff and shoulder
    3. Acute brachial plexus neuritis (Parsonage-Turner Syndrome)
    4. Thoracic outlet syndrome
    5. Herpes zoster
    6. Pancoast syndrome
    7. Sympathetically mediated syndromes
    8. Referred somatic pain from neck
12. Treatment
    1. Cervical soft collar, tight fitting, may be helpful - may only need to wear at night
    2. Physical therapy, with ultrasound treatments, may decrease pain
    3. NSAIDs of mild benefit
    4. Acetaminophen at 1gm tid-qid may be as effective as NSAIDs
    5. Prednisone 70mg po once daily, decreasing by 10mg each day, may be beneficial
    6. Translaminar and transoframinal epidural glucocorticoid injections (up to 60% effective)
    7. Intermittent cervical traction
    8. Cervical traction during sleep is particularly effective (after 7-14 days)
    9. Surgical intervention

F. Thoracic Outlet Syndrome [1,5]

1. Compression of the brachial plexus and vasculature (subclavian vessels)
2. Occurrance
   1. True syndrome is very uncommon
   2. Usually occurs in persons with repetative arm motions
   3. Whiplash injuries may exacerbate conditions
   4. Masses, including neoplasia and inflammatory lesions, may also cause syndrome
3. Symptoms
   1. Vague to severe pain in shoulder, medial arm and forearm
   2. Paresthesias and/or dysesthesias of medial forearm and ulnar two digits
   3. May have edema in affected upper extremity
4. Exam
   1. Thorough nerve and vessel exam
   2. Reversible, positionally dependent paresthesias
   3. Downward traction on arm decreases pulse
5. Studies
   1. EMG
   2. Radiographs may show a cervical rib
   3. CT scan or preferably MRI with angiography
6. Treatment
   1. Rest
   2. Weight loss
   3. Shoulder strengthening exercises
   4. Neck motion exercises; ultrasound treatments

G. Cubital Tunnel Syndrome [1,4]

1. Most common cause of ulnar neuropathy
2. Symptoms
   1. Pain and motor symptoms: weakness and dysesthesias in ulnar 4th and 5th digits
   2. Intrinsic muscle weakness and atrophy; increased symptoms on elbow flexion
3. Tinel's sign on elbow positive
4. EMG to confirm
5. Treatment
   1. Rest, elbow extension splint at night
   2. Surgical transposition in chronic cases

H. Ulnar Tunnel Syndrome

1. Pain and motor symptoms as above with intrinsic muscle weakness
2. Positive Allen Test: compression of radial artery at wrist leads to severe hand blanching
3. Positive Phalen's and Tinel's signs
4. Volar wrist splint, rest
5. Surgical release in chronic cases

I. Radial Nerve Syndromes

1. Radial Tunnel Syndrome
   1. Radial Nerve distal to elbow - pain syndrome (over extensor forearm)
   2. Weakness in wrist, thumb, and digital extension; resisted full digital extension
   3. EMG to confirm
   4. Rest, splint with elbow in flexion; surgical release in 8-12 weeks if treatment fails
2. Posterior Interosseous Syndrome
   1. Radial Nerve at forearm - pain and motor syndrome
   2. Pain fproximal forearm with weakness in thumb and digital extension
   3. EMG to confirm
   4. Treatment same as Radial Tunnel Syndrome

J. Tarsal Tunnel Syndrome

1. Entrapment neuroapthy of posterior tibial nerve at the ankle
2. Symptoms include aching, burning, tingling, numbness of plantar surface, radiate up calf
3. Usually occurs due to compression of posterior tibial nerve
4. Underlying conditions similar to carpal tunnel: hypothyroidism, inflammatory arthritis, amyloid, pregnancy.
5. Signs are variable, sometimes positive Tinel's sign by tapping on plantar foot surface
6. Diagnosis by nerve conduction study or MRI
7. Local injection or anti-inflammatory drugs are sometimes helpful
8. Surgical decompression may be required in severe cases

References

1. Dawson DM. 1993. NEJM. 329(27):2013
2. Katz RT. 1994. Am Fam Physician. 49(6):1371
3. Atroshi I, Gummesson C, Johnsson R, et al. 1999. JAMA. 282(2):153
4. Bracker MD and Ralph LP. 1995. Am Fam Physician. 51(1):103
5. Grasland A, Pouchet J, Regnard JF, Vinceneux Ph. 1998. Lancet. 352(9122):110
6. Carette S and Fehlings MG. 2005. NEJM. 353(4):392