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Posterior cord syndrome

Posterior cord syndrome (PCS), also known as posterior spinal artery syndrome (PSA) is a type of incomplete spinal cord injury .PCS is the least commonly occurring of the six clinical spinal cord injury syndromes, with an incidence rate of less than 1%, and it originates from the posterior spinal artery infarct. PCS is typically caused by disease, tumor, or injury, causing a transmission interruption of sensory information and motor commands from the brain to the periphery.

Etiology and symptoms
Posterior cord syndrome (PCS) is caused by lesions on the posterior portion of the spinal cord, specifically the posterior column, posterior horn, and posterolateral region of the lateral column. These lesions can be caused by trauma to the neck, occlusion of the spinal artery, tumors, disc compression, deficiency of vitamin B12, syphilis, or multiple sclerosis. Neck hyperflexion injuries can result from car accidents or sports related injuries. In these cases, posterior dislocations and extensions occur without the rupture of ligaments. During spinal artery occlusion, transient ischemic attacks cause ischemia to the cord. PCS may develop with the failure to treat syphilis, with symptoms appearing during the tertiary phase of the disease, usually between twenty and thirty years after the initial infection. This is due to the progressive degeneration of the nerve roots and posterior columns by the bacterium Treponema pallidum, resulting in locomotor ataxia and tabes dorsalis. Complications from tabes dorsalis include optic nerve damage, leading to blindness; shooting pains; urinary incontinence; and degeneration of the joints. Friedreich's Ataxia, an autosomal-recessive inherited disease, and tumors such as astrocytoma, ependyoma, meningioma, neurofibroma, sarcoma, and schwannoma are other common pathological sources of PCS. Cobalamin, commonly known as vitamin B12, plays a crucial role in the synthesis and maintenance of myelin in neurons found in the spinal cord. A deficiency of this essential vitamin results in demyelination, deteriorating the neuronal connections and interrupting signal transmission, with an unknown specificity to the posterior region.

Generally, lesions present bilaterally, although in very rare cases lesions have presented unilaterally. General symptoms of posterior spinal artery infarcts include loss of proprioception, light touch, and vibration; deep tendon areflexia; and paralysis below the portion of the spinal cord affected.

Diagnosis
Complete spinal imaging, plain x-rays, computed tomography (CT), or magnetic resonance imaging (MRI) can be used to show infractions on the dorsal columns. Although, imaging alone can be non-conclusive and clinical history, blood and cerebral spinal fluid (CSF) tests can also be used to complete a full diagnosis.

Treatment
The type of treatment received for patients with posterior cord syndrome depends on the symptoms of the patient and the source of infraction, however the main goal is to stabilize the spine. Possible treatments include airway adjuncts, the use of ventilators, full spinal precautions and immobilization, and injections of dopamine. While there is no definite cure for posterior cord syndrome, treatment and supportive care can be provided based on the symptoms of the patient.

Therapy including acute, definite, and rehab care can help ease the symptoms associated with PCS. Acute therapy can include intensive medical care and analgesia. Corticosteroids are used to reduce any inflammation or swelling. Bracing or surgical repair can be done to stabilize the spinal fracture. Walking aids as well as physical, occupational, and psychotherapy can alleviate PCS symptoms.

Research
Since symptoms of PCS are not specific in nature and can vary with the exact location of lesions on the cord it is difficult to make any breakthroughs in diagnosis or treatment. In addition, the demographics of patients suffering from PCS can be wide spread as the onset of symptoms usually follows a traumatic event. Another setback in research is the fact that PCS is extremely rare with few documented cases compared to anterior spinal cord injury. However, research has helped in differentiating PCS from brain injuries in order to develop better therapies for its treatment. For instance, one study suggests that a tissue plasminogen activator (tPA) therapy intervention, which is commonly used in stroke patients, might aid in treating the symptoms of PCS.