Myelopathy is a general term describing dysfunction of the spinal cord itself due to compression or injury. When this condition occurs in the mid-back, it is specifically referred to as thoracic myelopathy, affecting the spinal cord that runs through the T1 to T12 vertebrae. This condition represents a serious neurological issue because the pressure on the spinal cord can lead to progressive loss of function.
What Is Thoracic Myelopathy?
Thoracic myelopathy is a disorder resulting from severe physical compression of the spinal cord within the bony canal of the thoracic spine. The compression causes damage to the neural tissue, leading to a disruption of the signals traveling between the brain and the rest of the body. The thoracic spine is naturally more rigid than the neck (cervical) or lower back (lumbar) regions because it is stabilized by the rib cage.
The spinal cord in this region is particularly vulnerable because the spinal canal is relatively narrow, leaving less room for the cord to shift away from pressure. Furthermore, the thoracic cord has a less robust blood supply compared to other spinal regions, making it susceptible to ischemic damage when compressed. Myelopathy, which involves the spinal cord itself, is distinct from radiculopathy, which is the compression or irritation of a single nerve root as it exits the spine.
Common Causes of Spinal Cord Compression in the Thoracic Region
The causes of thoracic spinal cord compression can be broadly categorized into degenerative changes, traumatic injuries, and non-degenerative pathologies. Degenerative causes are the most common and typically develop slowly over time as the spine ages. These include conditions like spinal stenosis, which is a narrowing of the spinal canal often caused by bone spurs (osteophytes) and the thickening of ligaments.
One specific degenerative condition is the hypertrophy or ossification of the ligamentum flavum, a thick ligament that runs along the back of the spinal canal. When this ligament thickens or turns into bone, it can press directly on the spinal cord from behind. Thoracic disc herniation is another source of compression, though it is less common in the thoracic spine than in other spinal regions. Central disc herniations are most likely to cause myelopathy because they push directly into the spinal cord.
Non-degenerative causes can lead to a more rapid onset of symptoms. These include tumors, such as meningiomas or neurofibromas, which grow and take up space within the spinal canal. Infections, such as spinal epidural abscesses, or the presence of a hematoma (a collection of blood) can also quickly cause significant compression. Vascular anomalies, like dural arteriovenous fistulas, create abnormal blood flow patterns that may lead to spinal cord swelling and subsequent dysfunction.
Traumatic injuries, such as severe falls or motor vehicle accidents, can cause fractures and dislocations of the vertebrae. These injuries can lead to immediate, direct compression of the spinal cord by bone fragments or displaced vertebrae. In all cases, the mechanism of injury results in reduced space for the spinal cord.
Recognizing the Signs: Neurological Symptoms
The symptoms of thoracic myelopathy reflect the disruption of nerve pathways that control movement, sensation, and automatic body functions below the level of compression. Motor symptoms often manifest as a progressive stiffness, weakness, and heaviness in the legs. Patients frequently experience a clumsy or spastic gait disturbance, sometimes described as feeling like walking on sponges or having trouble lifting the feet.
Sensory changes are also common and can include numbness, tingling, or a pins-and-needles sensation in the legs and feet. A characteristic sign is the “girdle” or “band-like” sensation, where a person feels a tight, constricting band wrapped around their chest or abdomen at the level of the compression. This symptom is a direct result of sensory pathway damage in the thoracic cord.
Damage to the upper motor neurons in the spinal cord often results in hyperreflexia, which means the reflexes in the lower extremities are exaggerated or abnormally brisk. In more advanced cases, the condition can affect autonomic functions, leading to issues with bladder and bowel control. This loss of normal function, such as urinary retention or incontinence, indicates a more widespread impact on the spinal cord.
Clinical Evaluation and Management Options
The process of diagnosing thoracic myelopathy begins with a thorough physical and neurological examination. A physician will assess muscle strength, test reflexes for signs of hyperreflexia, and check for specific patterns of sensory loss. The doctor will also evaluate the patient’s gait and coordination to identify subtle walking difficulties that suggest spinal cord involvement.
Imaging is necessary to confirm the diagnosis and identify the precise cause and location of the compression. Magnetic Resonance Imaging (MRI) is the preferred imaging modality because it provides detailed visualization of the spinal cord, discs, ligaments, and any surrounding soft tissue masses. Other diagnostic tools, such as Computed Tomography (CT) scans, may be used to better visualize bony structures, or specialized electrical tests like electromyography (EMG) may be used to assess nerve function.
Management depends heavily on the severity of the neurological deficit and the cause of the compression. Conservative management, including physical therapy, activity modification, and pain medication, may be considered for mild symptoms or in cases where the compression is not severe. This approach aims to manage symptoms while closely monitoring the condition for progression.
However, if the myelopathy is progressive or severe, surgical decompression is typically the recommended treatment to prevent irreversible neurological damage. The goal of surgery is to physically relieve the pressure on the spinal cord by removing the offending structure, whether it is a herniated disc, a thickened ligament, or a tumor. Timely surgical intervention is important because the longer the spinal cord remains compressed, the lower the chance of a full neurological recovery.