P2.253: Post-Viral Cauda Equina Syndrome in a Pediatric Patient: A Diagnostic Challenge with Guillain-Barré Syndrome Mimicry

Introduction: Cauda Equina Syndrome (CES) and Guillain-Barré Syndrome (GBS) are uncommon illnesses in children which may present similarly with bilateral lower extremity pain and weakness. Both may follow viral infection; however, post-infectious and inflammatory CES is not well-documented. Due to increased influenza cases this year, a corresponding rise in rare post-viral complications including CES may be seen.

Case Description: A 10-year-old female presented with 48 hours of acute bilateral lower extremity weakness, pain, and difficulty ambulating two weeks after an Influenza A diagnosis. Examination revealed weakness and marked tenderness in the calves, thighs, hamstrings, and left sacroiliac joint. Achilles reflexes were absent. Laboratory studies including metabolic panel and creatine kinase were unremarkable. Spinal MRI showed subtle superficial enhancement of the lower thoracic spinal cord, conus medullaris, and cauda equina nerve roots concerning for GBS. Lumbar puncture and nerve conduction studies were not obtained.

Empiric treatment with intravenous immunoglobulin (IVIG) and gabapentin was initiated, resulting in rapid improvement in ambulation and pain after two doses. She was discharged after completion of five doses of IVIG with full strength, no pain, and the ability to walk unassisted.

That evening, her symptoms relapsed and progressed to include fecal incontinence. Examination remained consistent with previous admission exam, now with the addition of saddle anesthesia. Repeat labs were again unremarkable, including work up for vitamin deficiencies and thyroid labs. Given the abnormally rapid response to IVIG and subsequent relapse, her diagnosis was revised to non-structural CES (post-viral vs. post-inflammatory). Treatment included outpatient physical therapy and pain management with gabapentin, acetaminophen, and ibuprofen.

Discussion: The incidence of post-viral CES is unknown and represents a rare cause of CES. While CES is typically due to compressive lesions seen on imaging, post-viral cases may show nodular or smooth enhancement of cauda equina nerve roots. Pediatric patients may present with weakness and pain, mimicking other post-viral neurologic syndromes such as GBS. Since both can have overlapping clinical and imaging findings, cerebrospinal fluid analysis or nerve conduction studies may help differentiate the two. However, treatment of suspected GBS with IVIG should not be delayed during differentiation due to risks of autonomic dysfunction and respiratory failure. If post-viral CES is confirmed, early diagnosis and supportive care are essential to minimize long term neurological deficits such as bladder dysfunction, chronic pain, or motor weakness. The complications of delayed GBS and CES diagnosis and treatment are significant, highlighting the importance of intervention and close follow-up.

Conclusion: Reporting rare pediatric presentations enhances clinical awareness and may guide future management. Additional research is needed to clarify the pathophysiology and optimal treatment strategies for non-structural CES.