Carpal tunnel syndrome

In the clinical picture, carpal tunnel syndrome is manifested by paresthesia and pain in the fingers. Pain often radiates to the forearm, less often to the shoulder. Hypoesthesia is limited to the palmar surface of the first finger, the dorsal and palmar surfaces of the second to fourth fingers. Sensitivity on the palmar surface of the hand is not impaired, since the cutaneous branch to the inner half of the palm departs from the main trunk of the median nerve slightly above the wrist and is therefore not compressed. Unlike the round pronator syndrome, with compression of the median nerve in the carpal canal, paresis of the flexors of the fingers is not detected. At the wrist level, a motor branch departs from the median nerve, innervating the muscles of the outer part of the thenar of the first finger - the opposing, short abductor and short flexor of the thumb. The latter muscle has a double innervation from the median and ulnar nerves, so in carpal tunnel syndrome only weakness of opposition and abduction of the thumb is clearly revealed. Hypotrophy of the eminence of the first finger often occurs. Hyperhidrosis in the hand occurs with this disease more often than hypohidrosis. The main diagnostic tests are the wrist flexion test and the tapping symptom along the projection of the median nerve at the wrist level. Tourniquet and elevation tests have additional diagnostic value.

Differential diagnosis of various topographic variants of such syndromes along the median nerve is based on specifying the zone of paresthesia, hypalgesia, participation of the corresponding muscles (paresis, hypotrophy), data obtained during tapping and compression along the nerve, as well as electrophysiological data. In the clinical picture, the greatest proportion is occupied by paresthesia in the distal parts of the hands.

In the early stages of the disease, nocturnal paresthesias appear first, with great constancy and intensity. Patients wake up with a feeling of numbness and tingling mainly in the II-III fingers or the entire hand. In the initial phase of the disease, episodes of paresthesia occur 1-2 times a night and disappear a few minutes after waking up. Then, nocturnal paresthesias become frequent and painful, disturbing sleep. Long-term, intense manual labor during the day and the position of the hands on the chest contribute to nocturnal paresthesias. If a patient with bilateral tunnel syndrome turns on his side during sleep, paresthesias appear earlier in the upper limb lying above. Paresthesias can be stopped by rubbing and shaking the hand, tapping or hanging the upper limbs over the edge of the bed, or walking with swinging movements.

In the subsequent phase of the disease, daytime paresthesias also join in. Daytime paresthesias are provoked by intensive manual labor with prolonged tension of the finger flexor muscles (milking, carrying heavy objects, assembly work on a conveyor, writing, etc.), as well as movements of the upper limbs in an elevated position (painters, electricians, etc.).

During an attack of paresthesia, most patients also experience pain in the corresponding upper limb of unclear localization, mainly in its distal part (fingers, hand, forearm). Sometimes the pain spreads in the proximal direction - to the shoulder joint. The pain is dull, aching in nature and is felt in deep tissues. As the disease progresses, it intensifies and gradually becomes extremely pronounced, burning.

An early symptom of tunnel syndrome is morning numbness of the hands, which occurs before paresthesia and pain. After sleep, patients feel stiffness and swelling of the hands and fingers, but there are no clearly visible signs of edema. Morning numbness of the hands gradually weakens and passes in 20-60 minutes. The most common variants of localization of sensitivity disorders are the palmar surface of the third (92% of patients) and second fingers (71% of patients). Half of the patients have hypalgesia of the skin of the fourth finger, and 40% - of the first finger.

Motor disorders in carpal tunnel syndrome appear in the late stage of damage to the branches of the median nerve. At first, paresis of the corresponding muscles is detected, and after 2-3 weeks their atrophy also becomes noticeable (the thenar muscles atrophy first). For the clinical analysis of motor disorders, the variants of individual innervation of the thenar muscles are of great importance. During dynamometry, the compression force on the side of the tunnel syndrome is 10-25 kg less than in the healthy hand.

Vegetative disorders in carpal tunnel syndrome are common and manifest as acrocyanosis or pallor (spasm of the finger vessels), impaired sweating (hyper- or hypohidrosis, determined by ninhydrin dactylograms), changes in the trophism of the skin and nails (hyperkeratosis of the horny layer of the palm, clouding of the nail plate, etc.). Vasomotor disorders manifest themselves in increased sensitivity to cold, coldness of the hand during paresthesia attacks, and changes in the color of the skin of the fingers. If such manifestations are significant, a differential diagnosis must be made with Raynaud's disease. The attenuation of clinical manifestations after local injections of hydrocortisone or after surgical decompression of the carpal tunnel confirms their pathogenetic connection with tunnel syndrome.

Most often, carpal tunnel syndrome has to be differentiated from neurological manifestations of cervical osteochondrosis with discogenic (spondylogenic) lesions of the spinal roots CVI - CVIII. Both types of neurological pathology are often found in the same age groups and the coexistence of these diseases in the same patient is often possible. The following differential diagnostic signs can be identified.

1. Spondylogenic radicular syndrome is accompanied by vertebral symptoms (smoothness of the cervical lordosis, limited mobility of this section of the spine, painfulness of paravertebral points during palpation, spontaneous pain in the neck - cervicalgia), tension of the paravertebral muscles. These symptoms are absent in patients with carpal tunnel syndrome.
2. The localization of sensitivity disorders and the sequence of pain and paresthesia spreading are different. Pain and tactile sensitivity disorders in carpal tunnel syndrome are observed only in the area of the distal phalanges of the dorsal surface of the fingers, and in radicular syndrome, hypoesthesia spreads to the entire hand and forearm in the dermatome zone. Cervical osteochondrosis is characterized by the occurrence of pain and paresthesia from the area of the spinal column and shoulder girdle spreading in the distal direction. In carpal tunnel syndrome, paresthesia and pain begin in the distal part of the upper limb. Only with a significant increase in intense pain does it spread in the proximal direction to the elbow joint and not above the shoulder joint.
3. Motor disturbances in cervical radicular syndrome extend to the muscles of the corresponding myotome (these muscles are located on the hand, forearm and shoulder), deep reflexes in the hand are reduced. In carpal tunnel syndrome, paresis and hypotrophy of only the thenar muscles are detected.
4. Tests that provoke paresthesia in the upper limbs almost always cause paresthesia in the hand and fingers in carpal tunnel syndrome and are absent in cervical osteochondrosis.
5. Local injections of hydrocortisone into the carpal tunnel area eliminate pain and paresthesia in this tunnel syndrome. Such injections are ineffective in cervical osteochondrosis.

Radiological findings of cervical osteochondrosis should be interpreted only taking into account the characteristics of the clinical picture, since Vj patients with carpal tunnel syndrome also have radiological signs of degenerative-dystrophic changes in the cervical spine.

It is often necessary to differentiate carpal tunnel syndrome from spondylogenic scalene syndrome (Naffziger syndrome), in which paresthesia and pain extend to the entire upper limb, and after a night's sleep, swelling (pastosity) of the hand and its cyanosis are noticeable. Pulsation of the radial artery may decrease with deep inspiration and Edson's test. Hypesthesia occurs not only on the skin of the hand, but also on the forearm and shoulder. The flexion-elbow reflex is reduced. Palpation and tension of the anterior scalene muscle are painful. All these symptoms are absent in carpal tunnel syndrome.

In case of bilateral carpal tunnel syndrome, manifestations of polyneuritis (toxic, toxic-infectious), endogenous (dysmetabolic) polyneuropathy (diabetic, nephrogenic), and vibration disease should be excluded.

Local pain with irradiation in the distal and proximal directions from the hand occurs with damage to the ligaments and tendon sheaths. Irradiation of pain creates a complex impression of the involvement of the nerves of the entire hand in the process. This group of diseases is similar to carpal tunnel syndrome in the general mechanism of disease development - overstrain of the tendons and muscles of the hand. A combination of damage to the ligaments, tendon sheaths and the median nerve is often noted. In this case, it is necessary to distinguish a component of damage to the branches of the median nerve and a component of damage to the tendons and periosteal formations.

De Quervain's disease (styloiditis of the radius) is common, with pain spreading to the hand and 1st finger. However, the pain is localized along the radial surface of the hand and 1st finger, which is not observed in carpal tunnel syndrome. In de Quervain's disease, pain is most pronounced in the gloss of the styloid process of the radius. It is provoked by ulnar abduction of the hand; the amplitude of such abduction is limited. To verify de Quervain's disease, radiography of the styloid process is performed to detect soft tissue edema and local thickening of the dorsal ligament of the palm above the styloid process. In de Quervain's disease, paresthesia is rare and is associated with secondary involvement of the superficial branch of the radial nerve. In these cases, hypesthesia spreads to the dorsal surface of the hand, which is not observed in carpal tunnel syndrome.

Pain and movement disorders of the fingers occur with stenosing ligamentitis of the flexor tendon sheaths of the fingers. At the onset of the disease, pain occurs at the base of the fingers, sometimes the pain spreads to the back of the hand and the first and second fingers, which can create a false impression of the involvement of the branches of the median nerve. In differential diagnosis, it is taken into account that the pain intensifies when bending and unbending the fingers. Palpation of this area or pressure on the base of the fingers with a working tool also leads to increased pain. At a later stage, mobility in the interphalangeal joints is impaired ("snapping fingers"), differential diagnosis becomes easy.

Intermetacarpal tunnel syndrome occurs when the common digital nerve (n. digitalis communis) is affected at the level of the heads of the metacarpal bones, which is located in a special intermetacarpal canal. With repeated forced extension of the fingers, compression-ischemic damage to this nerve may develop in the main phalanx. The pain is localized in the area of the dorsal surface of the hand and spreads to the interdigital zone. In the acute phase, these pains often radiate in the proximal direction, as well as to the distal parts of the forearm. Similar localization of pain is observed during an exacerbation of carpal tunnel syndrome, which may cause an erroneous determination of the level of damage to the median nerve. When palpating between the heads of the metacarpal bones, projection paresthesia and pain in the surfaces of the fingers facing each other occur.

In the advanced stage of the disease, the hypalgesia zone is also determined here. Such local symptoms are not observed in patients with carpal tunnel syndrome.

Anterior interosseous nerve syndrome occurs when the branch of the median nerve below the pronator teres is affected. In such cases, the small distal branch of this nerve is first adjacent to the anterior interosseous membrane, then to the dorsal surface of the periosteum of the inner part of the radius, where it divides into a number of thin root branches that penetrate the dorsal carpal ligament and the capsule of the wrist joints. The anterior interosseous nerve innervates the radiocarpal and intercarpal joints from the front.

When the terminal branch of the anterior interosseous nerve is affected, pain occurs in the wrist area. To diagnose this neuropathy, a novocaine nerve block can be performed. The needle is inserted through the muscle - the round pronator - until it touches the bone, and then the tip of the needle is slightly pulled toward the center in the direction of the interosseous membrane. After anesthesia, the pain in the wrist temporarily stops and the function of the hand improves. A wrist hyperextension test also helps in diagnosis.

When the common trunk of the median nerve is damaged, paralysis and atrophy of all innervated muscles develops, the ability to flex the 1st and 2nd fingers, and to oppose the 1st finger to the 5th (fifth) finger is lost. This makes it difficult to grasp objects. The position of the 1st finger changes, it is located in the same plane as the others. Atrophy of the thenar muscles leads to flattening of the palm, and the hand acquires a pathological shape resembling a monkey's paw ("monkey hand"). The zone of sensitivity disorder due to overlap by adjacent nerves is smaller than the territory of pain sensations, and is mainly localized on the radial half of the palmar surface of the hand and the back of the distal phalanges of the 2nd-3rd fingers. Deep sensitivity is lost in the terminal interphalangeal joint of the 2nd finger. Pronounced vasomotor and trophic disorders in the area of the skin of the hand and nails (redness or blanching, hyperhidrosis or anhidrosis, hyperkeratosis or thinning of the skin, clouding of the nails, ulcers of the nail phalanx of the second finger) are not uncommon. With partial damage to the median nerve, there is causalgic pain and hypesthesia dolorosa, which is associated with the presence of sympathetic fibers in this nerve. With pronounced causalgic syndrome, reflex protective immobilization of the limbs with antalgic contracture develops.

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ]