Spinal Cord Compression

Spinal cord compression may develop acutely or by slow progression. Acute spinal cord compression is usually due to trauma (see above) or hemorrhage (e. g., epidural hematoma). Slowly progressive compression is usually due to a tumor, less commonly an abscess or granuloma. Other causes include deformities of the spine (kyphoscoliosis, ankylosing spondylitis), degenerative narrowing of the spinal canal (especially in the cervical region, see below), and massive intervertebral disk herniation.

Clinical manifestations that are typical of slowly progressive spinal cord compression include:

increasing stiffness or fatigability of the lower limbs,

more or less rapidly progressive gait impairment,

bladder dysfunction,

impaired sensation in one or both lower limbs,

bandlike paresthesiae around the chest or abdomen,

back pain.

Diagnostic evaluation. Neuroimaging usually provides definitive evidence of spinal cord compression; MRI is generally superior to CT for this purpose.

General aspects of treatment. The treatment is determined by the nature of the compressive lesion and is generally analogous to the treatment of corresponding lesions affecting the brain.

Spinal Cord Tumors

Tumors in the spinal canal can arise from the spinal cord tissue itself (intrinsic spinal cord tumors), from the spinal meninges (meningioma), or from the Schwann cells of the nerve roots (neurinoma). Tumors (particularly metastases) can also project into the spinal canal from the vertebral and paravertebral regions. Intrinsic spinal

cord tumors are intramedullary; leptomeningeal tumors are usually extramedullary, though still intradural. Tumors growing into the spinal canal from without are both extramedullary and extradural. Some highly invasive tumors arising in an extramedullary location can infiltrate the substance of the spinal cord, thereby becoming partly intramedullary.

In this section, we will briefly describe the more common varieties of spinal cord tumor.

Extramedullary Tumors

Metastases usually arise from the vertebral bodies and grow into the spinal canal. Their initial symptom is usually pain, which may be restricted to the site of the tumor, or else radiate in a radicular distribution. Paraparesis can arise quite rapidly thereafter, followed by bladder dysfunction. Clinical examination reveals the corresponding neurological deficits (pyramidal tract signs, possible sensory level, radicular segmental deficits) and, often, focal tenderness of one or more spinous processes to percussion. Neuroimaging studies are essential for the definitive diagnosis (Fig. 7.4). The most common primary tumors are carcinomas of the lung and breast, followed by carcinoma of the prostate gland.

Meningiomas arise from the spinal dura mater and account for one-third of all intraspinal masses. They are usually found in the thoracic and lumbar regions. They produce very slowly progressive gait impairment and spastic paraparesis, often over the course of several years, and have a characteristic appearance in imaging studies (Fig. 7.5).

Neurinomas (also called schwannomas) are nearly as common as meningiomas and, like them, are usually found in the thoracic and abdominal regions. They arise from the Schwann cells of the spinal nerve root sheaths. They nearly always present with radicular pain and radicular deficits. A neurinoma arising from a nerve root and straddling an intervertebral foramen, so that it has

Fig. 7.4 Metastatic carcinoma of the breast. The MR image reveals destruction of several thoracic vertebral bodies and spinal cord compression by tumor projecting into the vertebral canal at a mid-thoracic level.

Fig. 7.5 Extramedullary meningioma at T4, based on the ventral dura mater. Spinal cord compression is clearly visible. (T2-weighted MR image.)

Fig. 7.6 Neurinoma at C4, as seen by CT. The arrows indicate the intra and extraspinal portions of the tumor. The intraspinal portion compresses the spinal cord (c). (Image courtesy of the Neuroradiological CT Institute, PD Dr. H. Spiess, Zurich.)

both intraand extraspinal portions, is called a dumbbell or hourglass tumor (Fig. 7.6).

Meningeal carcinomatosis and leukemic meningitis can cause clinically evident spinal cord compression, in addition to pain (the most common symptom) and polyradicular neurological deficits.

Intramedullary Tumors

Intramedullary tumors are less common. Their manner of presentation depends on their location. The two most common types are astrocytoma and ependymoma; im-

Fig. 7.7 Intramedullary ependymoma in the conus medullaris, as seen in T1-weighted (a) and T2-weighted (b) MR images. The spinal cord is expanded, especially dorsally.

aging studies are essential for definitive diagnosis (Fig. 7.7).

Tumors are only one possible cause of slowly compressive spinal cord compression. Another very common cause is discussed in the next section.

Myelopathy Due to Cervical Spondylosis

Cervical myelopathy is often due to degenerative narrowing of the spinal canal with resulting spinal cord compression. Patients with inflammatory diseases of the spine, such as rheumatoid arthritis, are at elevated