Posterior cord syndrome

Overview

Posterior cord syndrome is a rare type of incomplete spinal cord injury characterized by damage to the posterior (dorsal) columns of the spinal cord. These columns are responsible for transmitting sensory information related to vibration, fine touch, and proprioception (the sense of body position). As a result, individuals with posterior cord syndrome experience significant sensory deficits, especially loss of proprioception, while motor function and pain and temperature sensation may remain relatively intact.

Although less common than other spinal cord syndromes, such as anterior cord syndrome or central cord syndrome, posterior cord syndrome can cause considerable functional impairment, particularly affecting balance, coordination, and mobility. Prompt recognition and management are crucial to minimize long-term disability and improve quality of life.

Causes

Posterior cord syndrome can result from a variety of traumatic and non-traumatic conditions that affect the dorsal aspect of the spinal cord. Common causes include:

• Trauma: Hyperextension injuries, vertebral fractures, or penetrating trauma to the posterior spinal cord.

• Spinal cord tumors: Compression from meningiomas or other tumors affecting the dorsal spinal cord.

• Multiple sclerosis: Demyelinating plaques that affect the dorsal columns.

• Vitamin B12 deficiency: Can cause subacute combined degeneration, affecting the posterior and lateral columns of the spinal cord.

• Syphilis (Tabes dorsalis): A late complication of untreated syphilis involving degeneration of the dorsal columns.

• Friedreich’s ataxia: A hereditary neurodegenerative disease that causes degeneration of the posterior spinal cord.

• Ischemia: Posterior spinal artery infarction, though rare, can result in selective damage to the posterior columns.

Symptoms

The symptoms of posterior cord syndrome are primarily sensory in nature, as the posterior columns transmit vibration, proprioception, and fine touch signals to the brain. Motor function is generally preserved. Common symptoms include:

• Loss of proprioception: Difficulty sensing the position and movement of limbs, leading to poor coordination and balance (especially with eyes closed).

• Ataxia: Unsteady gait and clumsiness due to impaired position sense rather than motor weakness.

• Loss of vibration sensation: Inability to feel vibrations in the feet or hands.

• Loss of fine touch: Reduced ability to detect subtle textures or distinguish between two points (reduced two-point discrimination).

• Positive Romberg sign: Worsening of balance when the eyes are closed, due to reliance on vision to compensate for lost proprioception.

• Urinary incontinence: May occur in some cases, depending on the extent and level of cord involvement.

Pain and temperature sensations, which are carried by the spinothalamic tract, are typically preserved. Weakness may be mild or absent unless other tracts are involved.

Diagnosis

Diagnosis of posterior cord syndrome involves a combination of clinical evaluation and imaging studies to identify the lesion and underlying cause. Diagnostic steps include:

• Neurological examination: Assessment of sensory deficits (proprioception, vibration), reflexes, and coordination. The presence of a positive Romberg test is a key finding.

• Magnetic Resonance Imaging (MRI): The gold standard imaging technique to visualize spinal cord lesions, tumors, demyelination, or ischemic damage.

• Blood tests: May include vitamin B12 levels, syphilis serology, and markers for autoimmune or inflammatory disorders.

• Lumbar puncture (spinal tap): Useful if multiple sclerosis or an infectious cause is suspected, to analyze cerebrospinal fluid (CSF) for abnormalities.

• Somatosensory evoked potentials (SSEPs): May be used to assess the integrity of sensory pathways in the spinal cord.

Identifying the underlying cause is essential for guiding treatment and preventing progression of symptoms.

Treatment

Management of posterior cord syndrome depends on the underlying cause, severity of symptoms, and progression. Treatment options include:

Medical Management

• High-dose corticosteroids: May be administered in acute traumatic or inflammatory cases to reduce spinal cord swelling and inflammation.

• Vitamin B12 supplementation: For cases caused by deficiency, typically given intramuscularly for rapid repletion.

• Antibiotics or antivirals: If an infectious cause like neurosyphilis or viral myelitis is identified.

• Immunomodulatory therapy: In cases of multiple sclerosis or autoimmune myelopathies.

Surgical Management

• Decompression surgery: May be necessary for spinal cord compression due to tumors, herniated discs, or trauma.

• Tumor resection: For cases involving intradural or extradural spinal neoplasms affecting the posterior cord.

Rehabilitation and Supportive Therapy

• Physical therapy: To improve balance, coordination, and ambulation.

• Occupational therapy: Helps with activities of daily living and fine motor skills.

• Assistive devices: Canes, walkers, or braces may be needed for mobility and fall prevention.

• Bladder training or catheterization: If urinary symptoms are present.

A multidisciplinary approach involving neurologists, physiatrists, physical therapists, and nutritionists is often beneficial.

Prognosis

The prognosis of posterior cord syndrome depends largely on the underlying cause, the speed of diagnosis, and the effectiveness of treatment. In some cases—such as B12 deficiency or demyelinating disease—early intervention can halt progression and lead to partial or full recovery. In contrast, cases resulting from extensive trauma or irreversible damage may result in long-term disability.

Factors influencing prognosis include:

• Extent and level of spinal cord involvement

• Underlying etiology (e.g., reversible vs. progressive)

• Timeliness and effectiveness of treatment

• Access to comprehensive rehabilitation services

With appropriate therapy, many individuals with posterior cord syndrome can regain independence in daily activities and maintain mobility, though some may experience residual sensory deficits or require long-term supportive care.