American Board of Psychiatry and Neurology (ABPN) Practice Exam 2025 - Free ABPN Practice Questions and Study Guide

The clinical presentation of lower extremity weakness and sensory loss following a flu-like illness strongly suggests acute transverse myelitis. This condition often occurs after viral infections, where the immune response can mistakenly attack the spinal cord, causing inflammation and resulting in both motor and sensory impairments.

Acute transverse myelitis typically presents with bilateral symptoms because it affects a segment of the spinal cord, resulting in deficits on both sides of the body. The rapid onset, coupled with the history of a preceding viral illness, aligns well with this diagnosis.

Other potential considerations, like a spinal epidural abscess or spinal metastasis, could present with similar symptoms, but these conditions would likely progress differently, often accompanied by other signs such as fever, profound pain, or neurological deficits that progress rather than occur acutely following an infection. Anterior spinal artery infarction would also show a different pattern of symptoms, typically presenting with a "suspension" of pain and temperature sensation below the level of the injury, while preserving proprioception and vibration.

Thus, given the history and symptomatology, acute transverse myelitis stands out as the most likely diagnosis in this case.