What symptoms do patients with a thoracic spine syrinx develop?

Symptoms of Thoracic Spine Syrinx

Patients with a thoracic spine syrinx typically develop progressive sensory deficits, motor weakness, and pain in a cape-like distribution, with potential for bowel and bladder dysfunction as the condition advances.

Clinical Presentation

The symptoms of a thoracic spine syrinx develop in a progressive pattern that reflects the anatomical disruption of the spinal cord. These symptoms can be categorized based on their neurological manifestations:

Sensory Symptoms

• Dissociated sensory loss (loss of pain and temperature sensation with preservation of touch, vibration, and proprioception)
• Cape-like distribution of sensory deficits across the upper back, shoulders, and arms
• Numbness and paresthesias that may begin in the upper extremities and progress downward
• Loss of pain sensation leading to painless injuries and burns

Motor Symptoms

• Progressive spastic paraparesis (weakness and spasticity in lower limbs)
• Hyperreflexia in the lower extremities
• Positive Babinski sign
• Muscle atrophy in affected myotomes
• Gait disturbances (reported in 6.8% of cases with vertebral involvement) 1

Autonomic Dysfunction

• Bladder dysfunction (neurogenic bladder)
• Bowel incontinence
• Sexual dysfunction
• Anhidrosis (decreased sweating)

Pain

• Neuropathic pain described as burning or electric-like
• Back pain at the level of the syrinx
• Radicular pain following dermatomes

Progression Pattern

The clinical course of thoracic syringomyelia typically follows a pattern of progression:

1. Early Phase: Subtle sensory changes, often asymmetric, with mild pain
2. Intermediate Phase: Development of motor symptoms and more pronounced sensory deficits
3. Advanced Phase: Significant motor weakness, autonomic dysfunction, and potential for permanent neurological damage

Special Considerations

Several factors influence the presentation of thoracic syrinx:

Etiology Impact

• Post-traumatic syrinx may present with symptoms at or below the level of injury 2
• Syrinx associated with arachnoiditis often presents with burning pain and sensory loss 3
• Idiopathic syrinx may have a more insidious onset with gradual progression 2

Syrinx Location and Extension

• Syrinx can expand rostrally, potentially reaching cervical levels and causing upper extremity symptoms 4
• Lower thoracic syrinx may predominantly affect lower extremities and bowel/bladder function
• Extensive syrinx spanning multiple levels has more widespread neurological effects

Diagnostic Challenges

• Symptoms may be misattributed to other conditions like multiple sclerosis or thoracic disc herniation
• Early symptoms can be subtle and intermittent, delaying diagnosis
• Neurological symptoms may be absent in up to 85.1% of cases in early stages 1

Clinical Evaluation

When evaluating a patient with suspected thoracic syrinx:

• Assess for dissociated sensory loss using pinprick and temperature testing
• Evaluate muscle strength, tone, and deep tendon reflexes
• Test for pathological reflexes (Babinski, Hoffman's)
• Assess for autonomic dysfunction (bladder function, orthostatic hypotension)
• Document the dermatomal pattern of sensory changes

Imaging Considerations

MRI of the thoracic spine without contrast is the first-line imaging modality for evaluating suspected syringomyelia 1. The imaging should include:

• Complete visualization of the entire spine to assess syrinx extent
• Evaluation for associated conditions (Chiari malformation, arachnoid web, tumor)
• Assessment of syrinx characteristics (location, size, septations)

Pitfalls and Caveats

• Symptoms may be attributed incorrectly to degenerative spine disease or peripheral neuropathy
• Intermittent symptoms can lead to delayed diagnosis
• Neurological deficits may become permanent if diagnosis and treatment are delayed
• Syrinx can expand over time, with worsening symptoms correlating with expansion 4
• Patients with minimal symptoms may still have significant syrinx on imaging

Understanding the progressive nature of thoracic syringomyelia is crucial for early diagnosis and intervention to prevent permanent neurological damage. The constellation of dissociated sensory loss, progressive motor weakness, and autonomic dysfunction should prompt consideration of this diagnosis and appropriate neuroimaging.