What are the signs of an anterior spinal artery infarct?

Signs of Anterior Spinal Artery Infarct

Anterior spinal artery infarction presents with a characteristic clinical syndrome including bilateral motor weakness, dissociative sensory loss, and autonomic dysfunction, with symptom onset typically ranging from minutes to 48 hours.

Clinical Presentation

Motor Symptoms

• Bilateral motor weakness below the level of the lesion
• Rapid progression of weakness (minutes to hours)
• Paraplegia or quadriplegia depending on the level of infarction
• Bilateral hand weakness may be the sole presentation in cervical cord infarcts 1
• "Man-in-the-barrel syndrome" in some cases 2

Sensory Symptoms

• Dissociative sensory loss (loss of pain and temperature sensation with preservation of vibration and position sense)
• Sensory level corresponding to the level of infarction
• Spinothalamic sensory deficits 1
• Pain (often severe neck or back pain) may be an initial symptom 2

Autonomic Dysfunction

• Urinary retention
• Bowel incontinence
• Anhidrosis below the level of lesion
• Sexual dysfunction

Timing and Progression

• Acute or subacute presentation with peak deficit within 72 hours 2
• Symptom onset to peak time ranging from minutes to 48 hours 2
• Often preceded by sudden severe neck or back pain

Neurological Examination Findings

• Flaccid paralysis in acute phase, later becoming spastic
• Hyperreflexia below the level of lesion (after spinal shock resolves)
• Babinski sign (upgoing plantar response)
• Loss of pain and temperature sensation with preserved proprioception and vibration
• Clear sensory level demarcation

Imaging Findings

• MRI is the diagnostic modality of choice 3
• T2-weighted images show hyperintensity in the anterior two-thirds of the spinal cord 4, 3
• Characteristic "owl eye" appearance on axial T2 images (37.5% of cases) 2
• "Pencil-like" hyperintensities on T2 sagittal images (100% of cases) 2
• Diffusion restriction may be present (seen in approximately 47% of cases) 2
• T1-weighted images may show hypointensity in chronic lesions 3
• Contrast enhancement may be present in some cases 3, 2
• MRI changes may evolve over time, similar to cerebral infarction 3

Distinguishing Features

• Anterior spinal artery syndrome affects the anterior two-thirds of the spinal cord 4, 3
• Preservation of posterior column function (vibration and position sense)
• Bilateral symptoms (unlike posterior spinal artery syndrome which is typically unilateral)
• CTA of the neck may depict injury of the anterior spinal artery 5

Risk Factors and Associated Conditions

• Aortic dissection or complications of aneurysm
• Thromboembolism
• Systemic hypotension 5
• Vertebral artery occlusion 1
• Atherosclerosis
• Cardiac surgery
• Spinal interventional procedures

Atypical Presentations

• Some patients may present with bilateral hand weakness without sensory deficits 1
• Symptoms may mimic other neurological conditions

Early recognition of these signs is crucial as spinal cord infarction can lead to significant morbidity, with outcomes ranging from complete recovery to permanent disability or death 2.