10.1 Carpal Tunnel Syndrome
Carpal tunnel syndrome (CTS) is a common clinical condition, occurring in 1 out of 50 people at any one time; over 50% present with bilateral disease. CTS is caused by compression of median nerve in the carpal tunnel. The ulnar nerve is not affected, as it lies above the carpal tunnel (▶Fig. 10.1).
Clinically, CTS presents with numbness, tingling, burning, and dull ache. Symptoms are predominately in the thumb, index, middle finger, and parts of the ring finger and sometimes the palm as well. Symptoms are most common at night and often relieved by shaking the hands on waking. These symptoms may recur during the day with activities such as driving, carrying objects, or typing. In some people, pain radiates up the forearm, sometimes even up to the neck. Rarely, people get weakness or clumsiness, skin changes (dryness, altered color).
10.1.1 Tests which aid in the diagnosis of CTS
Median nerve percussion test (Tinel’s sign): The test is positive when tapping the area over the median nerve at the wrist can produce paresthesia in the median nerve distribution. Sensitivity: 28–73%, specificity: 44–95%.
Carpal tunnel compression test: The test is considered positive when after applying pressure over the carpal tunnel for 30 seconds the patient′s sensory symptoms are duplicated. Sensitivity: 87%, specificity: 90%.
Phalen wrist flexion test (Prayer sign): It is positive when full flexion of the wrist for 60 seconds produces the patient′s symptoms. Sensitivity: 46–80%, specificity: 51–91%.
These are considered the gold standard in the diagnosis of CTS. This works by comparing the latency and amplitude of a median nerve segment across the carpal tunnel to another nerve segment that does not go through the carpal tunnel, such as the radial or ulnar nerve. A lot of factors, such as age, gender, finger diameter, concurrent systemic disease, obesity and temperature, may influence the amplitude and latency of an individual nerve. This is the most sensitive and accurate technique, with a sensitivity of 80–92% and specificity of 80–99%. However, false negative and false positives result in 16–34% of clinically defined CTS being mixed with NCS.
This test is normal (false negative cases) in up to 31% of CTS. Abnormal electromyography (EMG) with increased polyphasicity, positive waves, fibrillation potentials, and decreased motor unit numbers of maximal thenar muscle contraction is considered severe in degree and is an indication for surgery.
The use of US has been implicated in the diagnosis of CTS because thickening of the median nerve, flattening of the nerve within the tunnel, and bowing of the flexor retinaculum are features diagnostic of CTS. Comparison of the diagnostic utility of US with that of electrodiagnostic studies (EDS) found that the two techniques had almost equal sensitivities (i.e., 67.1 and 64.7% respectively). When these techniques were used together the sensitivity increased to 76.5%. However, a significant flaw is that 23.5% of patients with CTS remained undetected.
Magnetic resonance imaging (MRI)
MRI is excellent for picking up rare pathological causes of CTS (i.e., ganglion, hemangioma, or bony deformity). Furthermore, sagittal images may show accurately and allow the determination of the severity of nerve compression with a sensitivity of 96%, although specificity is extremely low at 33–38%. MRI is able to predict those patients who would benefit from surgical interventions, although the results do not correlate well with patient’s perceived severity of symptoms because MRI provides anatomical information as opposed to information on nerve impairment and function.
10.1.2 Contributing risk factors
CTS remains an idiopathic syndrome, but there are certain risk factors that have been associated with this condition. The most significant of these are:
Extrinsic factors that increase the volume within the tunnel (outside or inside the nerve)
Extrinsic factors that alter the contour of the tunnel
Intrinsic factors within the nerve that increase the volume within the tunnel
10.1.3 Differential diagnosis
Cervical radiculopathy (C6, C7)
Sensory symptoms (numbness and paresthesia)
May involve the thumb, index and middle fingers like in CTS although they may often radiate along the lateral forearm and occasionally the radial dorsum of the hand. In cervical radiculopathy, the pins and needles come and go, day and night, in an irregular way, never lasting more than an hour at a time whereas in CTS the pins and needles appear on using the hand. There are no paresthesias at rest, nor are they felt above the wrist.
Unlike the CTS, pain in cervical radiculopathy frequently involves the neck and may be precipitated by neck movements. Nocturnal exacerbation of pain is more prominent with CTS. Patients with radicular pain tend to keep their arms and neck still, whereas in CTS patients shake their arms and rub their hands to relieve the pain. Symptoms aggravated by coughing and sneezing are much more likely to be due to cervical radiculopathy than CTS.
It involves C6, C7-innervated muscles, not median-innervated C8 muscles. Brachioredialis and triceps tendon reflexes may be decreased or absent in radiculopathy.
In CTS, the symptoms are reproduced by provocative tests:
i. By tapping over the carpal tunnel (Tinel’s signs)
ii. By flexion of the wrist (Phalen’s sign)
iii. By a blood pressure cuff with compression above systolic pressure; median paresthesias and pain may be aggravated (cuff compression test of Gilliatt and Wilson)
They are usually diagnostic although both C6, C7 root compression and distal median nerve entrapment may coexist (double crush injury). Somatosensory evoked response EMG, orthodromic/antidromic etc.
It is usually incomplete and characterized by the involvement of more than one spinal or peripheral nerve producing clinical deficits such as muscle paresis and atrophy, loss of muscle stretch reflexes, patchy sensory changes, and often shoulder and arm pain which is usually accentuated by arm movement.
Upper plexus paralysis (Erb–Duchenne type)
The muscles supplied by the C5 and C6 roots are paretic and atrophic (i.e., deltoid, biceps, brachioradialis, radialis, and occasionally the supraspinatus, infraspinatus, and subscapularis) producing a characteristic position of the limb: Porter’s tip position (i.e., internal rotation and adduction of the arm, extension and pronation of the forearm and the palm is facing out and backward). The biceps and brachioradialis reflexes are depressed or absent. There may be some sensory loss over the deltoid muscle area.
Lower plexus paralysis (Dejerine–Klumpke type)
The muscles supplied by the C8 and T1 roots are paretic and eventually atrophic (i.e., weakness of wrist and finger flexion and weakness of the small hand muscles) producing a “claw hand” deformity. The finger flex- or reflex is depressed or absent. Sensation may be intact or lost over the medial arm, forearm, and ulnar aspect of the hand. Ipsilateral Horner’s syndrome with injury of the T1 root.
Neuralgic amyotrophy (Parsonage–Turner syndrome)
Otherwise known as idiopathic brachial plexitis. It begins typically with a prodrome of severe proximal limb pain followed in 7–10 days by marked weakness in one or more peripheral nerves with little numbness. Typically the distribution is not specifically in the distal median nerve distribution, although more proximal branches of the median nerve, such as the anterior interosseous nerve, may be affected. Such findings, out of the distribution of the median nerve in the carpal tunnel, argue strongly against the diagnosis of CTS. In doubtful cases, EDS can help sort out the pathology. The pain usually disappears within few days. The condition is idiopathic, but it is thought to be a plexitis and may follow viral illness or immunizations.
Thoracic outlet syndrome (cervicobrachial neurovascular compression syndrome)
The thoracic outlet syndrome may be purely vascular, purely neuropathic, or rarely, mixed. The true neurogenic thoracic outlet syndrome is rare that occurs more frequently in young women and affects the lower trunk of the brachial plexus. Initially the pins and needles are strictly nocturnal. There is mutational numbness, but hardly any symptoms during the day. This is the release phenomenon, i.e., the paresthesia appears only after cessation of the compression; the interval is related to the duration of the compression. Intermittent pain in the medial arm and forearm and the ulnar border of the hand is the most common symptom. Paresthesias and sensory loss involve the same distribution. The motor and reflex findings are essentially those of lower brachial plexus palsy, with particular involvement of the C8 root causing weakness and wasting of the thenar muscles similar to CTS. However, in contrast to the latter one, in the thoracic outlet syndrome wasting and paresis also tend to involve the hypothenar muscles which derive innervation from the C8 and T1 roots, and the sensory symptoms involve the medial arm and forearm where the arm discomfort is made worse with movement. EDS reveal evidence of lower trunk brachial plexus dysfunction.
This tumor can be confused with CTS in that the symptoms may be present in the hand, but the neurological distribution will be rather different depending on the specific location of the Pancoast tumor. It would be extremely unlikely for a tumor at the lung apex to specifically affect only the fibers pointing to the median nerve, particularly as some of these come from the medial cord and some from the lateral cord of the brachial plexus.
Similarly, postradiation neuritis of the brachial plexus can cause extreme pain, hand numbness, and hand weakness, but the pattern will not be limited to the median nerve distribution, and EDS will localize to the plexus and not to the wrist.
Proximal medial nerve neuropathy
It results due to the compression of the median nerve as it passes between the two heads of the pronator teres. It is characterized by:
i. Diffuse aching of the forearm
ii. Paresthesias in the median nerve distribution over the hand.
iii. Weakness of the thenar and forearm musculature (ranging from mild involvement to none)
iv. Pain in the proximal forearm upon forced wrist supination and wrist extension
The lacertus fibrosus syndrome
Pain in the proximal forearm is caused upon resisting forced forearm pronation of the fully supinated and flexed forearm.
The flexor superficialis arch syndrome
Pain in the proximal forearm is caused upon forced flexion of the proximal interphalangeal (IP) joint of the middle finger.
The anterior interosseous syndrome (purely a motor branch)
i. Weakness of the flexor pollicis longus (FPL), pronator quadratus, and the median-innervated profundus muscles. Impaired flexion of the terminal phalanx of the thumb and the index finger is characteristic.
ii. There is no associated sensory loss.
iii. Excessive supination/pronation seems to aggravate the pain.
Entrapment at the elbow (ligament of Struthers)
These can sometimes present with history of numbness or tingling in the hand, weakness in the hand, or loss of coordination in the hand. Often, these findings will be associated with hyperreflexia indicating that the diagnosis is more central. In addition, the pattern of weakness or hypoesthesia will typically not be in a distribution limited to that of the median nerve. Thus, a careful neurological examination, combined with appropriate imaging studies such as MRI, is the key factor in sorting out CNS neoplasia from CTS.
Multiple sclerosis can be superficially confused with CTS but can be readily distinguished by a careful neurological evaluation, since the diagnosis of multiple sclerosis requires, as its name suggests, multiple events and multiple sites of pathology, none of which would be typical for CTS. Other CNS disorders, such as amyotrophic lateral sclerosis or Charcot–Marie–Tooth (CMT) disease, are pure motor neuropathies that affect distal muscles diffusely, so that all the intrinsic muscles show weakness, and not just those of the thenar eminence.
This condition can also be confused with CTS. The characteristic patterns of numbness and weakness, however, are quite different reflecting the cervical spine origin of the symptoms.
Tumors within the peripheral nerves
Peripheral nerve tumors can simulate CTS. This can be particularly difficult if the tumor is within the carpal tunnel as is often the case with lipofibromatous hamartoma of nerve. The key distinction here will be a relatively long history of a mass. Unlike the swelling of the flexor synovium that one can see in CTS, the nerve tumor enlargement will not move with active finger motion. MRI is oftentimes useful in sorting out the diagnosis more specifically.
Amadio PC. Differential diagnosis of carpal tunnel syndrome. Springer-Verlag Berlin; 2007:89–94
Ibrahim I, Khan WS, Goddard N. Carpal tunnel syndrome: A review of the recent literature Open Orthop J 2012;6:69–76
Atroshi I, Gummesson C, Johnsson R, Ornstein E, Ranstam J, Rosén I. Prevalence of carpal tunnel syndrome in a general population. JAMA 1999;282(2):153–158
Burns TM. Mechanism of acute and chronic conversion neuropathy. In: Dyck PJ, Thomas PK, eds. Peripheral Neuropathy. 4th ed. Amsterdam Elsevier; 2005:1391–1402
Werner RA, Andary M. Carpal tunnel syndrome: pathophysiology and clinical neurophysiology. (Review) Clin Neurophysiol 2002;113(9):1373–1381
10.2 Ulnar Neuropathy
Ulnar nerve entrapment is the second most frequent entrapment neuropathy in the upper extremity. The elbow is the most common area of entrapment. Less common sites of entrapment include the arcade of Struthers, the medial intermuscular septum, the medial epicondyle, and the deep flexor pronator aponeurosis (▶Fig. 10.2).
10.2.1 Ulnar entrapment at the elbow (cubital tunnel syndrome)
The most common location (62–69%) is the nerve entrapment at the epicondylar groove from repeated subluxation of the nerve with elbow flexion over the medial epicondyle. Entrapment of the ulnar nerve as it enters the cubital tunnel is the next most common site (23–28%), and results as it enters the forearm via a narrow opening (cubital tunnel) formed by the medial humeral epicondyle, the medial collateral ligament of the joint, and the firm aponeurotic band to which the flexor carpi ulnaris is attached. Elbow flexion reduces the size of the opening under the aponeurotic band, while extension widens it. The frequency of ulnar nerve compression is increasing, partly due to the use of mobile phones, as the elbow is held flexed for long periods of time. “Tardy ulnar palsy” results from narrowing of the cubital tunnel secondary to an elbow fracture or in osteoarthritis, ganglion cysts, lipomas, or neuropathic (Charcot) joints.
Total paralysis of the nerve, including branches of the nerve serving the flexor digitorum profundus and flexor carpi ulnaris muscles, causes wasting along the medial side of the forearm.
Paralysis of the nerve also leads to weakness of flexion of the fourth and fifth fingers; if proximal portions of these fingers are held steady, the patient is unable to flex the terminal phalanges.
With paralysis of the hypothenar muscles, abduction of the fifth finger is impossible.
Paralysis of interossei and the medial two lumbricals causes “claw hand” deformity, mainly seen in the ulnar fingers.
There may be wasting of the hypothenar muscles, interossei, and the medial part of the thenar eminence. Further, there may be weakness in movement of fingers and abduction of the extended thumb against the palm.
There is sensory loss of the dorsal and palmar aspects of the medial side of the hand together with the medial one and a half fingers.
With compression of the ulnar nerve, the ulnar nerve is often palpably enlarged in the ulnar groove and for a short distance proximal to the elbow.
Tinel’s sign may be present and finger crossing usually abnormal.
10.2.2 Differential diagnosis
Cervical radiculopathy (C8/T1)
May cause sensory symptoms in the fourth and fifth fingers, and also along the medial forearm. Although the elbow is a common C8 referral site, pain is more proximal centering in the shoulder and neck.
Thoracic outlet syndrome/lower brachial plexopathy
Sensory symptoms involve not only the fourth and fifth fingers, but also medial forearm.
Weakness involves both the hypothenar and more severely the thenar muscles. If index finger extension is spared, you would tend to think lower trunk, not medial cord.
EDS show normal conduction and a lesion in the lower trunk of brachial plexus.
Dissociated sensory loss is characteristic with sparing of large-fiber sensation.
Median-innervated C8 motor function is impaired as well as ulnar function. There are often associated long track findings in the legs.
Electrodiagnosis shows normal ulnar sensory potentials due to the preganglionic nature of the lesion.
Sensory disturbances are not found.
Weakness and wasting of intrinsic hand muscles. Thenar muscles as well as the hypothenar muscles are often affected. Fasciculations may be present indicating the widespread nature of the disease.
Ulnar neuropathy at the wrist (Guyon’s canal)
Also known as handlebar palsy (seen in cyclists). The wrist is the second most common area of entrapment. It is caused by direct compression of the ulnar nerve in Guyon’s canal due to any of the following reasons:
10.2.3 Clinical presentation
Cutaneous sensation of the hand and fingers is often spared.
If the lesion is just proximal to the wrist, it causes impaired sensation of the palmar aspects of the hand and the fourth and fifth fingers, and muscle weakness, especially in the hypothenar eminence.
Clawing of ring and little fingers from loss of intrinsic muscles (adductor pollicis, deep head flexor pollicis brevis, interossei, and lumbricals 4 and 5).
Weakened grasp from loss of MCP joint flexion power.
Weak pinch from loss of thumb adduction (as much as 70% of pinch strength is lost).
Positive Tinel’s signs on percussion over the ulnar nerve at the wrist (light percussion over the nerve causes a sensation of “pins and needles” in the distribution of the nerve, i.e., the ulnar side of the hand and the fourth and fifth fingers).
Positive Phalen’s test with paraesthesias in the fourth and fifth fingers (the patient holds their wrist in maximum flexion for 30–60 seconds)
IP flexion compensating for loss of thumb adduction when attempting to hold a piece of paper.
Loss of MCP flexion and adduction by adductor pollicis (ulnar nerve)
Compensatory IP hyperflexion by FPL (anterior interosseous nerve)
A compensatory thumb MCP hyperextension and thumb adduction by extensor pollicis longus (radial nerve)
Compensates for loss of IP extension and thumb adduction by adductor pollicis (ulnar nerve)
Wartenberg’s sign: abduction posturing of the little finger
Difference between ulnar tunnel syndrome and cubital tunnel syndrome:
Kimura J. Mononeuropathies and entrapment syndromes: In: Kimura J, ed. Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice. 3rd ed. Oxford-New York; 2001:711–750
Tagliafico A, Resmini E, Nizzo R, et al. The pathology of the ulnar nerve in acromegaly. Eur J Endocrinol 2008;159(4):369–373
Andreisek G, Crook DW, Burg D, Marincek B, Weishaupt D. Peripheral neuropathies of the median, radial, and ulnar nerves: MR imaging features. Radiographics 2006;26(5):1267–1287
Murata K, Shih JT, Tsai TM. Causes of ulnar tunnel syndrome: a retrospective be study of 31 subjects J Hand Surg Am 2003;28A:647–651
Posner MA. Compressive ulnar neuropathies at the elbow: I. Etiology and diagnosis. J Am Acad Orthop Surg 1998;6(5):282–288
10.3 Claw Hand
(Also known as Spinster’s claw or ulnar claw)
It is a common clinical deformity, also known as the “intrinsic minus” hand. This is characterized by hyperextension of the metacarpophalangeal (MCP) joints and flexion of the proximal and distal IP joints (▶Fig. 10.2).
The ulnar nerve paralysis results in ulnar claw, where the clawing is confined to the little and ring fingers. The high ulnar palsy has less obvious clawing than the low ulnar palsy. There is loss of abduction/adduction of the fingers and wasting of the interosseous muscles, most obvious in the first web space and the hypothenar eminence. There will be numbness in the distribution of the involved nerve or nerves. Frequently in ulnar paralysis, the little finger remains permanently abducted from the ring finger (Wartenberg’s sign).
10.3.1 Causes
In this condition, all interossei as well as the ulnar-sided lumbricals are paralyzed, but the median nerve-innervated lumbricals to the index and middle fingers are preserved. As a consequence, the clawing is confined to the ring and little fingers and the thumb. The most common cause of ulnar nerve palsy is wrist laceration. Ulnar nerve compression at the elbow will cause ulnar claw and ulnar sensory loss. Spontaneous ulnar clawing with no sensory loss is most likely due to compression of the motor branch by a ganglion in the region of the pisohamate joint.
Paralysis of the ulna and median nerves
This produces a full claw hand. This deformity will also result from C8 and T1 nerve root lesions.
On a worldwide basis, leprosy still remains the most common cause of the claw hand.
10.3.2 Differential diagnosis
Certain conditions mimic the claw hand.
This deep flexor compartment compression syndrome results in ischemic necrosis of the profundus tendons in the forearm causing flexion contracture of the fingers. The superficialis tendons are usually spared, but intrinsic tendons may also be contracted. This produces flexion of all joints of the fingers rather than hyperextension of the MCP joints. The flexor tendons are tight.
This can be of ischemic origin, due to crash injuries and produces the opposite deformity in the claw hand, namely tight intrinsics, or intrinsic plus hand, rather the loose intrinsic minus claw hand. This condition spontaneously occurs in rheumatoid arthritis and may lead to Swan-neck deformity.
This typically involves the little and ring fingers and can mimic a claw hand, but the MCP joint is flexed and the contracted fingers cannot passively be extended. Palpation of the Dupuytren’s tissue in the palm confirms the diagnosis.
Congenital flexion contracture (camptodactyly)
This condition usually involves only the little finger, it is often bilateral and is hereditary. It is present at birth. The finger is flexed at the proximal IP joint and often cannot be passively fully straightened.
This condition results from an upper motor neuron palsy and usually involves a clasping deformity of the thumb in the palm and tightening of the flexor tendons that cannot be easily passively extended. The wrist is also characteristically flexed.
Various muscular dystrophies present as bizarre hand deformities of an atypical type.
Preston DC, Shapiro BE. Proximal, distal, and generalzed weakness. In: Daroff RB, Fenickel GM, Jankovic J, Mazziott JC, eds. Bradley’s Neurology in Clinical Practice. 6th ed. Philadelphia PA: Elsevier; 2012:chap 25
Sapienza A, Green S. Correction of the claw hand. Hand Clin 2012;28(1):53–66
10.4 Dupuytren’s Contracture
Dupuytren’s disease must be distinguished from several other conditions that affect the hand, including trigger finger, stenosing tenosynovitis, a ganglion cyst, or a soft-tissue mass. Unlike Dupuytren’s contracture, trigger finger typically involves pain with flexion followed by the inability to extend the affected digit (▶Fig. 10.3).
Stenosing tenosynovitis may be distinguished from Dupuytren’s disease by pain and a history of overuse or trauma. A small, movable nodule that is tender to palpation at the MCP joint is likely a ganglion cyst. A soft-tissue mass must also be excluded from the diagnosis, especially if the patient is significantly younger than the typical patient with Dupuytren’s disease and if he or she has no other risk factors.
A patient younger than age 40 years without involvement of the dorsal hand or foot is unlikely to have Dupuytren’s disease; however, then possibility of a sarcoma must be ruled out. Although the pathologic findings of a biopsy will most likely reveal a benign etiology (e.g., lipoma, inclusion cyst).
10.4.1 Differential diagnosis
Rayan GM. Dupuytren disease: Anatomy, pathology, presentation, and treatment. J Bone Joint Surg Am 2007;89(1):189–198
Young DM, Hansen SL. Current diagnosis and treatment: Surgery 13e; In: Doherty GM, ed. Chap 42 Hand Surgery. New York: The Mcgraw Hill Company; 2010
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
