Case 11

Case 11



HISTORY AND PHYSICAL EXAMINATION


A 30-year-old right-handed man developed neck and left parascapular pain over 2 weeks. Two days before presentation, his pain worsened and he had a radiating pain to the posterior aspect of the arm and numbness of the hand, particularly the index and middle fingers. He became aware of weakness of the left arm. His pain was exacerbated by coughing and neck movement. He denied any history of trauma. He had a history of left parascapular pain that occurred 2 years earlier, which responded to nonsteroidal anti-inflammatory agents. Otherwise, he had been in excellent health.


On examination, the range of neck movements was restricted in all directions. Lateral neck flexion to the left reproduced the left parascapular and arm pain. There was no atrophy or fasciculations. He had moderate weakness of the left triceps muscle (Medical Research Council [MRC] grade 4/5) and very mild weakness of the left wrist extensors (MRC grade 5–/5). All other muscles were normal. The left triceps reflex was trace. All other reflexes were 2/4. Sensory examination revealed no objective sensory impairment. Examination of the right upper and both lower extremities revealed no abnormalities.


Cervical spine x-rays showed reversal of the normal cervical lordosis with normal disk interspaces. Initially, the patient was treated conservatively with cervical traction, nonsteroidal anti-inflammatory agents, and analgesia. Ten days later, there was no improvement.


An electromyography (EMG) examination was then performed.


Please now review the Nerve Conduction Studies and Needle EMG tables.





DISCUSSION



Applied Anatomy


The dorsal root axons originate from the sensory neurons of the DRG, which lie outside the spinal canal, within the intervertebral foramen, immediately before the junction of the dorsal and ventral roots (Figure C11-1). These sensory neurons are unique because they are unipolar. They have proximal projections through the dorsal root, called the preganglionic sensory fibers, to the dorsal horn and column of the spinal cord. The distal projections of these neurons, called the postganglionic peripheral sensory fibers, pass through the spinal nerve to their respective sensory end-organs. The ventral root axons, however, are mainly motor (some are sympathetic, with origins from the anterolateral horn of the cord). The motor axons originate from the anterior horn cells within the spinal cord. Passing through the spinal nerves and the peripheral nerve, these motor fibers terminate in the corresponding muscles.



The spinal nerves terminate as soon as they exit the intervertebral foramina, by branching into posterior and anterior rami. The small posterior rami innervate the paravertebral skin and deep paraspinal muscles of the neck, trunk, and back; the large anterior rami innervate the skin and muscles of the trunk and limbs.


In humans, there are 31 pairs of spinal nerve roots: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. In the cervical spine, each cervical root exits above the corresponding vertebra that shares the same numeric designation (Figure C11-2). For example, the C5 root exits above the C5 vertebra (i.e., between the C4 and C5 vertebrae). Because there are seven cervical vertebrae but eight cervical roots, the C8 root exits between the C7 and T1 vertebrae; subsequently, all thoracic, lumbar, and sacral roots exit below their corresponding vertebrae. For example, the L3 root exits below the L3 vertebra (i.e., between the L3 and L4 vertebrae).




Clinical Features


Cervical radiculopathy frequently is the result of a herniated intervertebral disc, or osteophytic spondylitic changes that result in mechanical compression of the cervical root. The symptoms may be acute, subacute, or chronic. Neck pain radiating to the parascapular area and upper extremity, made worse by certain neck positions, is common. The pain radiation tends to follow the dermatomal innervation of the compressed root. Subjective paresthesias within the involved dermatome is more common than objective sensory findings. The diminution of deep tendon reflexes helps in localizing the lesion to one or two roots. Weakness is uncommon; when present, it involves muscles innervated by the compressed root.


The classic study by Yoss et al., published in 1957, remains the best available clinicoanatomic study of cervical root compression. This detailed study analyzed the symptoms and signs of 100 patients with surgically proven single cervical lesions. C7 radiculopathy was the most common cervical radiculopathy, accounting for almost two thirds of patients (Figure C11-3). Figure C11-4 shows the common sensory symptoms and signs observed in these patients, while Figure C11-5 shows the weakened muscles caused by cervical radiculopathy. This study revealed the extreme variability of sensory manifestations in patients with cervical radiculopathy. Also, no single muscle was exclusively diagnostic of a specific root compression. However, based on the data, certain clinical conclusions can be made:











However, despite the variability in sensory and motor presentations of cervical radiculopathies, certain classical symptoms and signs exist and are extremely helpful in localizing the compressed root. Table C11-1 reveals the common presentations of cervical radiculopathies.




Electrodiagnosis



General Concepts


Certain general concepts are essential to appreciate before one makes a diagnosis of a cervical radiculopathy in the EMG laboratory.





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Aug 12, 2016 | Posted by in CARDIOLOGY | Comments Off on Case 11

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