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Download بسم الله الرحمن الرحیم Entrapment Neuropathies
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بسم اهلل الرحمن الرحیم Entrapment Neuropathies Carpal tunnel syndrome (CTS) Ulnar neropathy at the elbow Thoracic outlet syndrome (TOS) Meralgia paresthetica Tarsal tunnel syndrome (TTS) Morton’s neuroma Patterns of weakness and sensory loss can identify which nerves are injured and localize the site of injury. Provocative maneuvers, which briefly increase pressure at a site of compression, aid diagnosis by recreating or exacerbating symptoms. Electrodiagnostic testing (EDX) should be performed to confirm the diagnosis Magnetic resonance imaging (MRI) or ultrasonagraphy should be performed to identify the source of compression Diagnosis of one entrapment neuropathy does not exclude another. such as carpal tunnel syndrome and cervical radiculopathy. This phenomenon is called a “double crush.” Symptoms and signs can overlap. EDX can also provide prognostic information. EDX often differentiate myelin dysfunction from axon damage. When a compressive lesion causes only focal demyelination, the injury is called neurapraxic, and carries a better prognosis for quick and complete recovery. Axon loss ,recovery will be slower and perhaps incomplete. CARPAL TUNNEL SYNDROME CTS is the most common and most studied entrapment neuropathy. PATHOLOGY The median nerve can be compressed as it passes through the carpal tunnel. The tunnel is at the base of the hand. The carpal, or wrist bones, form the floor of the tunnel and the flexor retinaculum forms the roof. Nine flexor tendons also pass through the tunnel. Due to this crowded arrangement, tenosynovial proliferation, fluid collection, or arthritic deformity can lead to carpal tunnel syndrome. Epineural ischemia(impede flow to arteries) Intraneural edema(venous stasis) SYMPTOMS • Numbness on the palmar surface of the thumb and index, middle, and half of the ring finger Patients are often not aware of the true distribution of numbness and may report that all five fingers are involved. The pain can be both distal and proximal to the site of compression. Patients can report pain in the hand, wrist, elbow, and shoulder. Carpal tunnel syndrome should be considered in any obscure complaint of pain in the arm. symptoms at night/Driving “flick sign”(needing to shake hand) Patients usually do not complain of weakness. They may report dropping things or having difficulty with certain motor activities like doing up buttons or opening a jar. PHYSICAL FINDINGS The median nerve after it exits the carpal tunnel supplies sensation to the palmar surface of the thumb and index, middle, and half the ring finger. It also supplies the dorsal tips of these same fingers. The palmar branch of the median nerve, which supplies sensation to the proximal portion The palm and thenar eminence, does not go through the carpal tunnel, and is therefore spared in carpal tunnel syndrome. Phalen’s maneuver Tinel’s sign ELECTRODIAGNOSIS sensitivity as high as 95%. The hallmark of electrodiagnosis is a delay in the distal latency of median nerve conduction. Rule out cervical RAD/ TOS/ diff PNP TREATMENT splinting to maintain the wrist in a neutral position Anti-inflammatory Surgical decompression RISK FACTORS computer use flexion and extension at the wrist obesity, arthritis, diabetes, and hypothyroidism shape of the wrist ULNAR NEUROPATHY AT THE ELBOW Ulnar nerve entrapment at the elbow is the second most common neuropathy in the upper extremity. Entrapment can occur either at the ulnar groove or at the cubital tunnel. PATHOLOGY The ulnar nerve is particularly vulnerable to compression or stretch as it crosses the elbow and passes through the cubital tunnel. The ulnar groove is formed by the medial epicondyle and the olecranon process. The nerve is also vulnerable to impingement if there is a bony deformity or scar formation. Patients with a remote history of supracondylar fracture can develop such a bony deformity and nerve impringement in what has been called “tardy ulnar palsy.” SYMPTOMS Intermittent numbness and tingling in the distribution of the ulnar nerve is usually the first symptom of ulnar palsy. Patients can wake up with elbow pain radiating into the fifth digit. There can be cramping and aching in the hypothenar eminence. Symptoms can be exacerbated by flexion of the elbow. Patients may complain about a generalized loss of strength in the hand or loss of dexterity. PHYSICAL FINDINGS The ulnar nerve supplies sensory fibers to the fifth finger, both palmar and dorsal surfaces, and usually in some individuals the ulnar nerve may supply the whole ring finger and even part of the long finger. weaken grasp and pinch strength( froment sign) Difficulty addacting the fifth digit(wartenberg sign) Clawing of digits 4&5 and finger abduction weakness (Benediction Posture) Weakness of ulnar flexor digitorum Atrophy of the hypothenar eminence and the first dorsal interosseous can often be seen. tenderness with palpation and Flexion of the elbow ELECTRODIAGNOSIS EDX testing is necessary to confirm a diagnosis and to exclude other causes including brachial plexopathy, cervical radiculopathy, and an ulnar entrapment at the wrist. NCS will usually show slowing across the elbow and sometimes a drop in response amplitude across the elbow. Inching techniques can sometimes localize the site of compression to the ulnar groove or the cubital tunnel. TREATMENT Mild cases of ulnar palsy at the elbow can be successfully treated with an elbow pad to reduce trauma to the nerve or by avoiding prolonged flexion at the elbow. More severe cases may require surgery. The precise site of entrapment will determine the surgical procedure, which can include transposition of the nerve, decompression at the aponeurosis, or even medial epicondylectomy. RISK FACTORS Resting a bent elbow on a hard surface is a behavior that can provoke ulnar palsy. For example, truck drivers can develop a left ulnar palsy from resting their elbow on the window of the truck while driving. Direct trauma including elbow fractures can cause acute ulnar nerve injury. Delayed or tardy ulnar palsies can result from bony deformities that develop after trauma or fracture. THORACIC OUTLET SYNDROMES (TOS) There are many structures that can compress or impinge the brachial plexus as it enters the arm. Vascular structures can also be compressed in the same way. Various positions of the shoulder can also compromise both vascular and neural structures in the thoracic outlet. PATHOLOGY A cervical rib is the most discussed source of compromise in TOS, but easily identified by x-ray An anomalous fibrous band from the transverse process of the last cervical vertebra to the first rib is a common cause of impingement. by the scalenes, subclavius, and pectoralis minor muscles have all been reported. Hyperextension injuries of the neck can lead to intrascalene muscle hemorrhage and swelling with resultant scar formation in the muscle or around the brachial plexus. Most commonly in neurogenic TOS the lower trunk of the brachial plexus is most involved. Vascular syndromes usually involve compromise of the axillary and subclavian vessels/Flow studies SYMPTOMS The symptoms of TOS depend on whether they are primarily arterial, venous, or neurologic and can vary with shoulder position. In the arterial form, symptoms are ischemic in nature and include pain, paresthesia, coldness, and color change. Venous symptoms can include swelling, and cyanosis, as well as pain and paresthesia. Neurogenic symptom -numbness of the medial forearm and ulnar side of the hand. aching pain, poorly localized in the arm and anterior chest. clumsiness or weakness in the hand and fingers. Atrophy of both the thenar and hypothenar eminences can be seen. Elicit symptoms with Anterior flexion and Abduction and supination of the arm PHYSICAL FINDINGS the lower trunk of the brachial plexus-sensory deficits on the ulnar weakness and atrophy of the thenar eminence syndrome progresses, sensory loss can involve all five fingers. True neurogenic TOS initially causes weakness of median innervated hand muscles and later ulnar innervated muscles. Atrophy of both thenar and hypothenar eminences can occur Provocative tests Adson’s maneuver involves extending the arm at shoulder height to the side and supinating the hand .loss of radial pulse, and an increase in sensory symptoms. The Elvey maneuver stresses the brachial plexus by again extending the arm to the side and then tilting the head to the opposite side ELECTRODIAGNOSIS Reduction in the amplitude of the medial antebrachial cutaneous sensory response. Later ulnar sensory responses in the hand will be diminished. Late responses such as F-waves will become prolonged and conductions across the plexus will be slowed as plexopathy progresses. Needle examination may elicit denervation changes in both median and ulnar innervated hand muscles in advanced cases. TREATMENT Correction of shoulder posture Exercises that strengthen the rhomboid and trapezius muscles Clavicle straps Surgery-The most common surgical procedures are resection of cervical rib and fibrous band, and calenectomies. Both procedures carry significant morbidity. The injection of botulinum toxin into the scalene muscles subclavius, pectoralis minor, trapezius, and levator scapula also have been injected with good results in some patients. Potential complications of botulinum toxin injections in this area include dysphagia, dysphonia, and muscle weakness. MERALGIA PARESTHETICA Entrapment of the lateral femoral cutaneous nerve of the thigh has been well described for over 100 years. PATHOLOGY The lateral femoral cutaneous nerve of the thigh (L2&L3)arises from upper lumbar roots, travels through the pelvis, and exits into the leg at the upper lateral end of the inguinal ligament. The nerve is usually trapped as it passes under or through the inguinal ligament. Blunt trauma to this area can cause damage to the nerve. More chronic episodic external compression from tightfitting clothes, a holster, or tool belt can provoke meralgia. increased intra-abdominal ressure from weight gain or pregnancy. Mass lesions, including lipomas and fibroids, have been reported in some cases. SYMPTOMS unpleasant sensations and numbness in the lateral thigh. Light touch in the area can be unpleasant. PHYSICAL FINDINGS The lateral femoral cutaneous nerve is a purely sensory nerve that supplies just the lateral thigh. ELECTRODIAGNOSIS difficult to elicit sensory responses from the lateral femoral cutaneous nerve in normal individuals. TREATMENT Pain control with medication is the standard treatment. Reduction of risk factors Nerve blocks Surgical intervention RISK FACTORS Obesity Pregnancy Diabetes tight-fitting clothes Pelvic osteotomy stabilization devices during spine surgery TARSAL TUNNEL SYNDROME posterior tibial nerve at the medial ankle PATHOLOGY The tarsal tunnel is formed by the ankle bones and the flexor retinaculum. Through the tunnel passes the posterior tibial nerve, tendons of the foot and toe flexors, and the posterior tibial artery. Increased pressure in the tunnel brings on the syndrome. This can occur from an ankle fracture or sprain, arthritic changes, tenosynovitis, or fluid collection. Mass lesions in the tarsal tunnel like ganglion cysts or convoluted blood vessels, SYMPTOMS foot pain Burning Painful numbness Walking and standing can exacerbate symptoms PHYSICAL FINDINGS Intrinsic foot muscles primarily toe flexors and abductors, can be affected but clinical testing of these muscles can be difficult. Pressure Painful Eversion and dorsiflexion can also provoke symptoms ELECTRODIAGNOSIS motor and sensory slowing through the tarsal tunnel. Needle examination of intrinsic foot muscles can be misleading TREATMENT Anti-inflammatory medication Surgical decompression is highly effective RISK FACTORS Ankle trauma Rheumatoid arthritis diabetes mellitus both increase the risk for tarsal tunnel syndrome INTERDIGITAL NEUROPATHY (MORTON’S NEUROMA) Pressure on an interdigital nerve in one of the intermetatarsal spaces can cause pain and numbness in the distal foot and toes. PATHOLOGY The interdigital nerves are distal branches of the lateral and medial plantars. actual scar Neuroma This most commonly occurs between the third and fourth metatarsal heads but can involve other interdigital nerves. SYMPTOMS burning pain in the ball of the foot that radiates to one or two toes. The corresponding toes may feel numb. Pain will be worse with weight bearing. PHYSICAL FINDINGS Pain can be elicited by pushing on the ball of the foot over the affected interdigital nerve. A neuroma can often be visualized with MRI or ultrasound. ELECTRODIAGNOSIS Difficult and often unreliable. Both orthodromic and antidromic sensory or mixed nerve studies using both surface electrodes and near-needle electrodes have been described, but none are routinely performed. excluding other neuropathologies that also manifest with foot pain and numbness, in particular TTS, lumbosacral radiculopathy, and generalized PNP. TREATMENT physical therapy, orthotics, and avoiding offending footwear are often successful. Interdigital anesthetic nerve blocks, often with corticosteroids, have been effective in some patients. A variety of surgical interventions have been used, all with some success. RISK FACTORS Activities that increase trauma to the foot can all increase one’s risk for interdigital neuropathy. Ill-fitting shoes, especially high heels, also predispose one to develop Morton’s neuroma. باتشکر
