Neurology · Spinal Cord Injury
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Anterior cord syndrome is caused by infarction of the anterior spinal artery, typically resulting from aortic cross-clamping or aortic dissection.
Patients present with bilateral loss of motor function below the level of the lesion due to damage to the corticospinal tracts.
The syndrome is characterized by bilateral loss of pain and temperature sensation below the level of the lesion due to damage to the spinothalamic tracts.
Proprioception, vibration, and fine touch are preserved because the dorsal columns are supplied by the posterior spinal arteries.
The clinical presentation involves flaccid paralysis initially, which later progresses to spastic paralysis as upper motor neuron signs develop.
Autonomic dysfunction, specifically bladder and bowel incontinence, is a common clinical finding due to disruption of descending autonomic pathways.
MRI of the spine is the diagnostic modality of choice to confirm the presence of an acute spinal cord infarction.
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A 62-year-old male is brought to the emergency department following an emergent repair of a thoracic aortic aneurysm. Post-operatively, the patient is unable to move his lower extremities. Physical examination reveals bilateral loss of pain and temperature sensation from the T10 dermatome downward. However, the patient retains intact vibration and proprioception in both lower extremities. Deep tendon reflexes are currently absent in the lower limbs.
What is the most likely diagnosis?
Anterior cord syndrome
The patient exhibits the classic dissociation of sensory loss (pain/temperature lost, vibration/proprioception preserved) and motor paralysis characteristic of anterior spinal artery injury following aortic surgery.
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Etiology / Epidemiology
Caused by anterior spinal artery infarction or flexion injury of the cervical spine.
Clinical Manifestations
Loss of motor function and pain/temperature sensation below the lesion with preserved proprioception/vibration.
Diagnosis
MRI spine is the gold standard to rule out compression or hemorrhage.
Treatment
Immediate stabilization and surgical decompression if secondary to compression.
Prognosis
Generally poor; only 10-20% of patients achieve significant motor recovery.
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Epidemiology & Etiology
Most commonly associated with aortic cross-clamping during thoracic surgery or aortic dissection. Also occurs following cervical flexion injuries causing vertebral body retropulsion. Central cord syndrome is the most common incomplete spinal cord syndrome.
Pertinent Anatomy
The anterior two-thirds of the spinal cord are supplied by the anterior spinal artery. The posterior columns, supplied by the posterior spinal arteries, remain intact. This anatomical distribution dictates the specific sensory-motor dissociation.
Pathophysiology
Ischemia or mechanical compression disrupts the corticospinal tracts (motor) and spinothalamic tracts (pain/temp). Because the dorsal columns are supplied by the posterior spinal arteries, they are spared. This results in the classic dissociated sensory loss pattern.
Clinical Manifestations
Patients present with bilateral paralysis and loss of pain/temperature sensation below the level of injury. Proprioception and vibration sense are preserved. Autonomic dysfunction including bladder/bowel incontinence is common. Brown-Séquard syndrome is the primary differential to exclude.
Diagnosis
The MRI spine is the diagnostic modality of choice to visualize cord signal changes. If MRI is unavailable, CT myelography may be utilized. Always assess for spinal shock, characterized by flaccid paralysis and areflexia.
Treatment
Management focuses on hemodynamic stabilization to maintain spinal cord perfusion pressure. Surgical decompression is indicated if there is evidence of extrinsic compression. Avoid hypotension as it exacerbates ischemic injury.
Prognosis
Prognosis is guarded with low rates of functional recovery. Long-term management requires multidisciplinary rehabilitation and monitoring for pressure ulcers and neurogenic bladder complications.
Differential Diagnosis
Central Cord Syndrome: disproportionate upper extremity motor deficit
Brown-Séquard Syndrome: ipsilateral motor loss with contralateral pain/temp loss
Posterior Cord Syndrome: loss of proprioception/vibration with preserved motor
Cauda Equina Syndrome: saddle anesthesia and bowel/bladder dysfunction
Transverse Myelitis: bilateral sensory/motor loss with distinct sensory level