Magnetic resonance imaging evaluation of Wallerian degeneration of bilateral middle cerebellar peduncles after pontine infarction

Abstract

We aimed to present a case of symmetrical Wallerian degeneration (WD) in the middle cerebellar peduncles (MCPs) after a unilateral paramedian pontine infarction, which was examined by multimodality magnetic resonance imaging (MRI). In addition, we summarize the small number of reported cases. In our clinic, we observed a case of symmetrical WD of bilateral MCPs that occurred 6 months after the onset of a pontine infarction. We searched the Wanfang (Chinese) and PubMed databases and found 23 reported cases of this condition with characteristic similar to our patient. From the 24 cases, the detection time of WD ranged from 3 to 33 weeks. Symmetrical WD in the bilateral MCPs can occur after unilateral paramedian pontine infarction. Most cases were in Stages 2 and 3 of the disease and showed good clinical prognoses.

Bilateral wallerian degeneration of middle cerebellar peduncles following unilateral pontine infarction

“…The specific neuroimaging finding of symmetrical hyperintensities in the medial cerebellar peduncles can be interpreted as wallerian degeneration of pontocerebellar tracts following pontine infarct [5]. Wallerian de-generation should be considered when the primary infarct site is close to the secondary site, but not in the same region of the vascular innervations [6]. The exact mechanism underlying the pathogenesis of bilateral medial cerebellar peduncles' lesions is unknown.…”

“…Third stage (14 weeks to several years) is characterized by hyperintensities on T2weighted imaging and hypointensities on T1-weighted imaging. Fourth stage occurs after several years and is characterized by shrinkage of the white matter fiber tracts with volume loss [6]. Interestingly, wallerian degeneration can also present with restricted diffusion on diffusion-weighted imaging especially during the first and third stages and should be differentiated from a new infarction [1].…”

“…Wallerian degeneration of the pontocerebellar tracts is considered to be easier to diagnose in the third stage because new neurological deficits, though rare, can appear in this period, but mostly because conventional magnetic resonance imaging can detect abnormal signals [1]. Clinical presentation can be new onset ataxia, dysarthria, vertigo, hearing impairment and dyskinesias [6]. However there is no absolute association between the time of symptom onset and the stage of wallerian degeneration from magnetic resonance imaging findings.…”