Thoracic Spinal Cord Injury: Diagnosis & Treatment

Diagnosis and Treatment of Thoracic Spinal Cord Injury By Wise Young, Ph.D., M.D. W. M. Keck Center for Collaborative Neuroscience Rutgers University, Piscataway, New Jersey http:sciwire.com, last updated 23 July 2005

Many people have been asking for an article about diagnosis and treatment of thoracic spinal cord injury. The following is a short description of upper and mid-thoracic spinal cord injury, emphasizing the anatomy, the neurology, treatment, recovery, and long-term changes, and hope for recovery and therapies.

Anatomy

The thoracic spinal cord is situated in the T1-T9 thoracic spinal canal. The thoracic vertebral segments form the chest wall and have ribs. The thoracic segments are the best protected of all the vertebral segments because of the ribs. It takes enormous forces to fracture the thoracic spinal vertebral bodies. Traumatic injuries of the upper thoracic spinal cord are relatively rare, accounting for only 10-15% of spinal cord injuries (compared to 40% due to cervical, 35% due to thoracolumbar injuries, and 5% due to lumbosacral injuries). Thoracic spinal cord injuries occur as a result of high-speed motor vehicular accidents, tumors that have compressed the spinal cord, and ischemic injuries of the spinal cord. When traumatic injuries of the thoracic spinal cord occur, they generally are severe and often result in complete loss of neurological function below the injury site.

Details of the anatomy are worthwhile noting. The C1 roots exit the spinal column just above the C1 vertebral body, that there is a C8 spinal segment but no C8 vertebral segment. The C8 root therefore exits the vertebral column between C7 and T1. The T1 root exits the spinal column below T1. The thoracic spinal roots form the intercostal nerves (nerves that run on the underside of the ribs). Although many clinicians say and believe mistakenly that the thoracic segments do not have a significant motor component and that all they control are the intercostal muscles for breathing, this is not true. As it turns out, the thoracic segments control muscles that attach to the ribs (which include the abdominal muscles, as well as most of the back muscles).

Neurology

Injury to the thoracic spinal cord causes paraplegia, or loss of motor and sensory function in the lower half of the body. Because the thoracic cord is situated some distance from the brain and lumbar cord, sensory and motor axons have a long ways to regenerate before they can restore function. Nevertheless, substantial sensory and motor recovery occurs in a majority of people with mid-thoracic injuries, even those with initially "complete" spinal cord injury. For example, recovery of 4-6 dermatomes of sensory function and upper trunk/abdominal muscles is common. Diagnosis of spinal cord injury usually is based on sensory examination. The axillary (armpit) region is T2, the nipples T4, the bottom of the rib cage is T8, the umbilicus (belly button) is T10, and the suprapubic region is T12.

The cervical segments innervate superficial trunk muscles such as the scapula and the latissimus dorsi. Multiple overlapping thoracic segments innervate most deeper trunk muscles. Injury to the thoracic spinal cord will cause partial paralysis of deeper trunk muscles such as the cervicis (T1-5), splenius (T3-T6), erector spinae and iliocostalis (T6-12), spinalis (T1-9), semispinalis, transversospinal, and segmental (T1-12) muscles. The thoracic segments and upper lumbar segments innervate the abdominal muscles including the rectus abdominus (T4-L3), external oblique (T6-L3), transverse abdominis (T9-L3), and internal oblique (T12-L3). The posterior oblique (T6-10) and the anterior oblique (T4-8) muscles attach to the lower and upper thoracic ribs respectively. In general, muscles above the belly button are innervated by T5-T11 while muscles below the belly button are innervated by T12 and L1.

Causes of Injury

Decompression of the thoracic spinal cord often requires surgery because traction alone often cannot reposition the thoracic vertebral segments. Because surgery on the thoracic spinal column usually requires the opening of the thoracic cavity, decompression of thoracic spinal cord injury may be delayed by many hours, days, or even weeks after injury. Continued compression of the spinal cord contributes to the damage. In my opinion, delays in decompressing the spinal cord contribute to neurological loss in thoracic spinal cord injuries. Compression of the spinal cord causes ischemia or loss of blood flow to the spinal cord. Pressure on the spinal cord exceeding blood pressure will reduce or stop blood flow to the spinal cord. Continued compression for many hours, days, or even weeks is likely to cause further damage to the spinal cord.

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Thoracic Spinal Cord Injury: Diagnosis & Treatment