Absent F-waves in conus medullaris stroke mimicking Guillain-Barré syndrome

Spontaneous conus infarction with "snake-eye appearance" on magnetic resonance imaging: A case report and literature review

BACKGROUND

Infarction of the conus medullaris is a rare form of spinal cord infarction. The first symptom is usually acute non-characteristic lumbar pain, followed by lower limb pain, saddle numbness, fecal incontinence, and sexual dysfunction. Spontaneous conus infarction with "snake-eye appearance" on magnetic resonance imaging has rarely been reported.

CASE SUMMARY

We report a 79-year-old male patient with spontaneous conus infarction who had acute lower extremity pain and dysuria as the first symptoms. He did not have any recent history of aortic surgery and trauma. Magnetic resonance imaging revealed a rare "snake-eye appearance." In addition, we reviewed the literature on 23 similar cases and summarized the clinical features and magnetic resonance manifestations of common diseases related to the "snake-eye sign" to explore the etiology, imaging findings, and prognosis of spontaneous conus infarction.

CONCLUSION

We conclude that acute onset of conus medullaris syndrome combined with "snake-eye appearance" should be strongly suspected as conus medullaris infarction caused by anterior spinal artery ischemia. This special imaging manifestation is helpful in the early diagnosis and treatment of conus infarction.

Isolated Infarctions of the Conus Medullaris: Clinical Features and Outcomes

OBJECTIVE

This study aims to describe the clinical features and outcomes of patients with isolated infarctions of the conus medullaris, and to identify factors associated with poor functional outcomes.

MATERIALS AND METHODS

We performed a systematic review and retrospective analysis on the clinical characteristics and outcomes of patients with isolated conus medullaris infarctions reported in literature over the past 30 years.

RESULTS

We analyzed a total of 19 cases; 18 identified in literature from January 1991 to June 2021, together with our patient. Their median age was 56 years (range 28-79), with twice as many females as males. Pain was prominent at onset (15/19, 79%), only a third had vascular risk factors (7/19, 37%), and half had no significant preceding activities or events (9/19, 47%). Almost all experienced paraplegia or paraparesis (16/19, 84%), in which upper motor neuron features were rare (3/19, 16%). The underlying cause was unknown in half (10/19, 53%). Functional outcomes appeared fair, with nearly half being capable of unassisted ambulation (9/11, 82%). Patients with vascular risk factors (67% vs 13%, p = 0.024) or with identified underlying causes (78% vs 13%, p = 0.007) were less likely to walk unassisted.

CONCLUSION

Isolated conus medullaris but should be considered in patients with acute cauda equina syndrome, especially in females. Patients with vascular risk factors, or with known causes of infarction, are less likely to walk unassisted. DWI sequences should be included in conventional MRI sequences when evaluating patients with acute cauda equina syndrome.