Post-operative paediatric cerebellar mutism syndrome: time to move beyond structural MRI

Abstract

PurposeTo determine the value of structural magnetic resonance imaging (MRI) in predicting post-operative paediatric cerebellar mutism syndrome (pCMS) in children undergoing surgical treatment for medulloblastoma.MethodsRetrospective cohort study design. Electronic/paper case note review of all children with medulloblastoma presenting to Great Ormond Street Hospital between 2003 and 2013. The diagnosis of pCMS was established through a scoring system incorporating mutism, ataxia, behavioural disturbance and cranial nerve deficits. MRI scans performed at three time points were assessed by neuroradiologists blinded to the diagnosis of pCMS.ResultsOf 56 children included, 12 (21.4%) developed pCMS as judged by a core symptom of mutism. pCMS was more common in those aged 5 or younger. There was no statistically significant difference in pre-operative distortion or signal change of the dentate or red nuclei or superior cerebellar peduncles (SCPs) between those who did and did not develop pCMS. In both early (median 5 days) and late (median 31 months) post-operative scans, T2-weighted signal change in SCPs was more common in the pCMS group (p = 0.040 and 0.046 respectively). Late scans also showed statistically significant signal change in the dentate nuclei (p = 0.024).ConclusionsThe development of pCMS could not be linked to any observable changes on pre-operative structural MRI scans. Post-operative T2-weighted signal change in the SCPs and dentate nuclei underlines the role of cerebellar efferent injury in pCMS. Further research using advanced quantitative MRI sequences is warranted given the inability of conventional pre-surgical MRI to predict pCMS.

Functional Outcomes of Cerebellar Malformations

“…Furthermore, compared to patients who did not develop PFS, those who experienced PFS had a consistent alteration in white matter integrity based on DTI of the bilateral SCP, as well as white matter changes in associated non-sensorimotor cortical areas (Morris et al, 2009). The involvement of the proximal dentatothalamocortical pathway due to damage to the SCP was replicated in a subsequent study using conventional MRI image processing [namely fluid-attenuated inversion recovery (FLAIR) and diffusion weighted imaging (DWI]) (Toescu et al, 2018b). This study also found changes in the dentate nucleus in patients with PFS, though this appeared to be a late onset pathology, rather than an acute problem tightly associated with behavioral morbidity (Toescu et al, 2018b).…”

“…Numerous studies have been undertaken to evaluate the changes in cerebellar structure and connectivity in patients who have experienced PFS (Morris et al, 2009; Patay et al, 2014; Avula et al, 2016; Toescu et al, 2018a, b). An evaluation of factors predisposing medulloblastoma patients to development of PFS found that tumor location proximal to the SCP made development of PFS more likely (Morris et al, 2009).…”

Quantitative MRI in post-operative paediatric cerebellar mutism syndrome

“…In recent years, magnetic resonance imaging (MRI) has been able to provide a [19,27,41,50], though a seminal paper in the field reported that more rostrally located fourth ventricle tumours had a significant statistical association with pCMS [18]. Early post-operative structural MRI showing oedema in middle or superior cerebellar peduncles is likely to be associated with pCMS [19,27], and generalised atrophy of the brainstem and cerebellar structures on delayed follow up MRI has been shown to be significantly more likely in pCMS [27].…”

Feasibility of cerebello-cortical stimulation for intraoperative neurophysiological monitoring of cerebellar mutism

“…The leading hypothesis for the occurrence of CM is mono-or bilateral disconnection of the efferent pathway from the cerebellum to the cortex, namely the cerebello-dentothalamo-cortical (CDTC) pathway [16]. This has been supported by a vast number of recent neuroimaging as well as lesion studies, showing that CM is associated with large [17], midline [18] tumours residing in proximity of the fourth ventricle and predicted by damage of the superior cerebellar peduncles, the dentate nucleus or the CDTC pathway itself [19]. Although tractography can improve preoperative surgical planning or predict postoperative deficit [19], its intraoperative reliability is limited by tissue displacement and brain-shift phenomena [20].…”