Disorders of the Spinal Cord and Vertebral Bodies

Abstract

The spinal cord extends caudally from the medulla to the first or second lumbar vertebrae in adults and slightly lower in infants. Spinal cord functions are not solely passive but also modulate or generate many afferent and efferent pathways. Spinal cord dysfunction results from traumatic, inflammatory, demyelinating, ischemic, nutritional, and degenerative conditions. The chapter begins with a discussion of common major clinical features and mechanisms of damage of the spinal cord. Clinical signs depend on the level of the spinal cord damage and whether the damage involves part or all of the cord. Diseases affecting the spinal cord may present as degenerative with loss of specific spinal cord elements, focal lesions at one or more level of the spinal cord, or compression of spinal cord nerve roots that are exiting the vertebra. Three common diseases of the spinal cord are discussed in detail, amyotrophic lateral sclerosis, acute transverse myelitis, low back pain with radiculopathy or lumbar spinal stenosis, with attention to their pathophysiology, major clinical features, major laboratory findings, and principles of management and prognosis.

A 45-year-old healthy woman executive who is an avid jogger first noted that her time to complete a 2-mile jogging course became progressively longer. Over the next 3 months, she became more fatigued after exercising and her endurance was less. By 6 months, she noted twitching in both leg muscles plus a few arm muscles even on days when she did not exercise. Her internist noted brisk deep tendon reflexes but her muscle strength and sensation appeared normal. Laboratory tests for anemia, electrolytes, and liver function were normal. No diagnosis was made. By 9 months, she knew her leg muscles were weak. She saw a neurologist who found mild atrophy and weakness in several leg muscles, spontaneous fasciculations in both arm and leg muscles, and mild atrophy and fasciculations of her tongue. Her deep tendon reflexes were brisk and she had bilateral Babinski signs. MRI of her spinal cord was normal but the electromyogram demonstrated fibrillations and positive sharp waves in many arm and leg muscles. A variety of blood tests were normal. A diagnosis of amyotrophic lateral sclerosis was made based on the multiple spinal cord levels of both upper and lower motor neuron disease plus involvement of bulbar muscles.

Video Legend

This video shows a 62 year-old man with Amyotrophic Lateral Sclerosis (ALS).

Segment 1: Cranial Nerve Exam

• Normal eye movements

• Normal jaw, neck and tongue strength

Segment 2: Motor Exam

• Distal weakness in upper extremities

• Marked atrophy of hand muscles

• Observing for muscle fasciculation

• Signs of upper motor neuron lesion with spasticityon tone exam

Segment 3: Reflex Exam

• Mixed findings of both hyperreflexia (upper motor neuron) and absent reflexes (lower motor neuron) characteristic of ALS