Arm and Neck Pain

Chapter 29 Arm and Neck Pain




Evaluation of the patient with arm and/or neck pain is based on a careful history and clinical examination. Diagnosis of the common causes and a treatment plan can almost always be accomplished in the office before laboratory investigation, but further study may be required if the patient fails to improve or has other specific indications for imaging or electrical studies.


A useful approach is to consider the diagnosis in terms of pain-sensitive structures in the neck and upper limbs. These structures may be part of the nervous system or may involve joints. Neurological causes should be considered in terms of the innervation of the neck and arm, and non-neurological causes are based on dysfunction of the other anatomical structures of the arm or neck. Because nerve root irritation generates neck muscle spasm, this type of pain is usually lumped into the “neurological” category. Some essentially non-neurological conditions have neurological complications and are grouped in this chapter as “in-between” disorders.



Clinical Assessment



History



Neurological Causes of Pain






Plexus Pain


Peripheral pathology may involve the brachial plexus (Fig. 29.1) or individual nerves extending to the hand. Infiltrative or inflammatory lesions of the brachial plexus produce severe brachialgia radiating down the upper limb and also spreading to the shoulder region. Radiation to the ulnar two fingers suggests that the origin is in the lower brachial plexus, and radiation to the upper arm, forearm, and thumb suggests an upper plexopathy. Patients with a thoracic outlet syndrome complain of brachialgia and numbness or tingling in the upper limb or hand when working with objects above the head.







Examination


The physical examination is designed to localize a neurological deficit related to spinal cord, nerve roots, or peripheral nerves. Evaluation for non-neurological pathology is required because rheumatological problems often complicate a primarily neurological problem. A detailed knowledge of motor and sensory neuroanatomy is required for accurate localization.



Motor Signs


The examination begins with inspection. Particular attention is paid to atrophy of muscles of the shoulders, arms, and the small muscles of the hands. Fasciculations are often due to anterior horn cell disease, but they may be part of the neurology of cervical spondylosis and radiculopathy. Significant sensory signs would argue against anterior horn cell degeneration.


Muscles in the various myotomes must be tested individually. When there is unilateral weakness, the contralateral side can act as a control, but some standard measure of strength is necessary for accurate evaluation when bilateral weakness is present. If one can overcome the action of a patient’s muscle by resisting or opposing its action close to the joint it moves, using an equivalent equipotent muscle of the examiner (fingers test fingers, whole arm tests biceps), then that muscle in the patient is, by definition, weak. The degree of weakness can be graded, and the 5-point (Medical Research Council [MRC]) grading scale is often used. Grade 5 represents normal strength. Grade 4 represents “weakness” somewhere between normal strength and the ability to move the limb only against gravity (grade 3). Grade 4 covers such a wide range of weakness that it is usually expanded. One simple expansion is into “mild, moderate, or severe.” When the muscle can move the joint with the effect of gravity eliminated, it is graded at 2, and grade 1 is just a flicker of contraction.


The lower limbs must always be examined, even when the patient complains of symptoms only in the upper limbs. Evidence of a myelopathy as evidenced by the finding of sensory or motor dysfunction in the lower limbs, when combined with the presence of radicular signs in the upper limbs, indicates a spinal cord lesion in the neck.


The distribution of weakness is all important in localizing the problem to nerve root, plexus, peripheral nerve, muscle, or even upper motor neuron (central weakness). It is useful to use a simplified schema of radicular anatomical localization when evaluating nerve root weakness because overlap of segmental innervation of muscles can complicate the analysis (Table 29.1).


Table 29.1 Segmental Innervation Scheme for Anatomical Localization of Nerve Root Lesions











































Segment Level Muscle(s) Action
C4 Supraspinatus First 10 degrees of shoulder abduction
C5 Deltoid Shoulder abduction
  Biceps/brachialis/brachioradialis Elbow flexion
C6 Extensor carpi radialis longus Radial wrist extension
C7 Triceps Elbow extension
C7 Extensor digitorum Finger extension
C8 Flexor digitorum Finger flexion
T1 Interossei Finger abduction and adduction
  Abductor digiti minimi Little finger abduction

The thoracic outlet syndrome, or brachial plexus entrapment, is an overdiagnosed condition. Maneuvers designed to test for compromise of the neurovascular structures passing through the thoracic outlet are often difficult to interpret. In these maneuvers, the arm is extended at the elbow, abducted at the shoulder, and then rotated posteriorly. The examiner palpates the radial pulse while listening with a stethoscope over the brachial plexus in the supraclavicular fossa. The patient takes a deep inspiration and turns the head to one or the other side. Many normal individuals lose their radial pulse, but the emergence of a bruit does suggest at the least vascular entrapment (Adson test). The patient then exercises the hands held above the head with extended elbows—numbness, pain, or paresthesias, often with pallor of the hand, support the diagnosis (Roos test).


A distribution of weakness that does not conform to a clearly defined anatomical distribution of a single peripheral nerve in the upper limb suggests plexopathy. Upper plexus lesions cause mainly shoulder abduction weakness, and lower plexus lesions will affect the small muscles of the hand.






Pathology and Clinical Syndromes



Spinal Cord Syndromes




Extramedullary Lesions


Extramedullary lesions may result in any combination of root, central cord, and long-tract signs and symptoms. The most common cause of extrinsic nerve root and spinal cord compression is cervical spondylosis. This is a degenerative disorder of the cervical spine characterized by disc degeneration with disc space narrowing, bone overgrowth producing spurs and ridges, and hypertrophy of the facet joints, all of which can compress the cord or nerve roots. Hypertrophy of the spinal ligaments, with or without calcification, may contribute to compression. Hypertrophic osteophytes are present in approximately 30% of the population, and the incidence increases with age. The presence of such degenerative changes does not indicate that the patient has symptoms due to these changes; astuteness in diagnosis is necessary. Furthermore, the degree of bony change does not always correlate with the severity of the signs and symptoms it produces. This degenerative process is sometimes referred to as hard disc as opposed to an acute disc herniation or soft disc in which the onset is acute with severe neck pain and brachialgia. Patients with cervical spondylosis often awake in the morning with a painful stiff neck and diffuse nonpulsatile headache that resolves in a few hours. The lesion is most commonly at C5/6 and C6/7, and focal signs are likely to be at these levels. Wasting and weakness of the small muscles of the hands, particularly weakness of abduction of the little finger, is also frequently seen. These signs localize to lower segmental levels, but there may be no observable anatomical change at those levels, and then they are referred to as false localizers. Restricted neck movement is always present with significant cervical spondylosis. Bladder dysfunction, indicated by frequency, urgency, and urgency incontinence or the finding of long-tract signs or symptoms, indicates the need for imaging of the cervical spine both to exclude other pathology and to define the severity of the spinal cord compression. Immobilization in a cervical collar often helps with the symptoms and signs of cervical spondylosis. The role of surgery in treatment is discussed in Chapter 75.


Extramedullary compression in the extradural space is usually due to primary or metastatic tumors. Of the primary tumors commonly encountered, a schwannoma produces signs and symptoms related to the nerve root on which it arises, and as it enlarges, progressive myelopathic dysfunction occurs. Plain radiographs of the cervical spine may demonstrate an enlarged intervertebral foramen, but MRI is diagnostic. A meningioma may present in a somewhat similar fashion but is more frequent in the thoracic region.


Epidural spinal cord compression due to metastatic malignancy presents initially with spine pain in over 90% of patients. Malignant bone pain is usually localized to the vertebra involved, and percussion tenderness is a good localizing sign, even in the neck. As the pathology spreads to the epidural space, radicular pain appears. Plain radiographs of the cervical spine may show bony pathology with preservation of disc spaces, and again, the imaging modality of choice is MRI. The whole spinal column should be scanned because the pathology is often at multiple sites and may be subclinical. Spinal cord compression due to metastatic disease is a neurological emergency requiring treatment with immediate high-dose steroids and local irradiation. Occasional patients are referred for surgery.


Epidural infection (abscess) may be either acute and pyogenic or more chronic when the organism is mycobacterial or fungal. Pyogenic epidural abscess usually presents acutely with fever, severe pain localized to a rigid neck, radicular pain, and rapidly progressing root and myelopathic signs. Sometimes the presentation is more subacute with less systemic evidence of infection. Imaging will usually reveal early destruction of the disc, with spread into the epidural space; only later is there spread to bone, with vertebral collapse. Optimal therapy is surgical decompression and evacuation combined with 6 to 12 weeks of appropriate antimicrobial therapy for pyogenic infections and more prolonged treatment for tuberculosis.


The differential diagnosis of a very rapidly progressing painful epidural lesion includes spinal epidural abscess and spinal subarachnoid, subdural, or epidural hemorrhage. The latter are usually associated with some form of coagulopathy or anticoagulant therapy and sometimes with vascular anomalies or trauma. The sudden onset of severe pain in the neck, with or without radicular pain, may be due to hemorrhage. Reversal of the coagulation deficit, if present, should be followed by decompression.


The sudden onset of pain at the back of the neck with associated posterior fossa signs suggests vertebral artery dissection. The diagnosis is easily made with MRI and fat suppression sequences.


Repetitive sudden shooting pains radiating from the occipital region to the temporal areas or vertex suggests the diagnosis of occipital neuralgia. There may be local tenderness over the greater or lesser occipital nerve, and a local injection of corticosteroid plus local anesthetic is both diagnostic and therapeutic. Failure to respond suggests that the craniovertebral junction area should be imaged.

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Jun 19, 2016 | Posted by in NEUROLOGY | Comments Off on Arm and Neck Pain

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