Cerebellar mutism syndrome and its relation to cerebellar cognitive and affective function: Review of the literature

Improved prediction of postoperative paediatric cerebellar mutism syndrome using an artificial neural network

Background

Postoperative paediatric cerebellar mutism syndrome (pCMS) is a common but severe complication which may arise following the resection of posterior fossa tumours in children. Two previous studies have aimed to preoperatively predict pCMS, with varying results. In this work, we examine the generalisation of these models and determine if pCMS can be predicted more accurately using an artificial neural network (ANN).

Methods

An overview of reviews was performed to identify risk factors for pCMS, and a retrospective dataset collected as per these defined risk factors from children undergoing resection of primary posterior fossa tumours. The ANN was trained on this dataset and its performance evaluated in comparison to logistic regression and other predictive indices via analysis of receiver operator characteristic curves. Area under the curve (AUC) and accuracy were calculated and compared using a Wilcoxon signed rank test, with p<0.05 considered statistically significant.

Results

204 children were included, of whom 80 developed pCMS. The performance of the ANN (AUC 0.949; accuracy 90.9%) exceeded that of logistic regression (p<0.05) and both external models (p<0.001).

Conclusion

Using an ANN, we show improved prediction of pCMS in comparison to previous models and conventional methods.

Cerebellar Mutism Treated Successfully With Zolpidem in a Patient With Learning Difficulties

Posterior fossa tumors constitute the most common brain tumor in pediatrics with 25% development postresection. Cerebellar mutism can manifest as neurobehavioral abnormalities that can occur within days to months after surgery but usually peak on the third postoperative day. It can be caused by discontinuation of dento-thalamo-cortical pathway in the vermian lesion, due to edema, tumors, and hypoperfusion. We report a seven-year-old patient with posterior fossa lesion (pilocytic astrocytoma in histopathology) and learning difficulties with symptoms of urinary retention, pseudobulbar palsy, and motor incoordination that were treated successfully with zolpidem 2.5 mg with regain of function by the third month.

Cerebellar Calcium-Binding Protein and Neurotrophin Receptor Defects in Down Syndrome and Alzheimer's Disease

Cerebellar hypoplasia is a major characteristic of the Down syndrome (DS) brain. However, the consequences of trisomy upon cerebellar Purkinje cells (PC) and interneurons in DS are unclear. The present study performed a quantitative and qualitative analysis of cerebellar neurons immunostained with antibodies against calbindin D-28k (Calb), parvalbumin (Parv), and calretinin (Calr), phosphorylated and non-phosphorylated intermediate neurofilaments (SMI-34 and SMI-32), and high (TrkA) and low (p75NTR) affinity nerve growth factor (NGF) receptors as well as tau and amyloid in DS (n = 12), Alzheimer's disease (AD) (n = 10), and healthy non-dementia control (HC) (n = 8) cases. Our findings revealed higher Aβ42 plaque load in DS compared to AD and HC but no differences in APP/Aβ plaque load between HC, AD, and DS. The cerebellar cortex neither displayed Aβ40 containing plaques nor pathologic phosphorylated tau in any of the cases examined. The number and optical density (OD) measurements of Calb immunoreactive (-ir) PC soma and dendrites were similar between groups, while the number of PCs positive for Parv and SMI-32 were significantly reduced in AD and DS compared to HC. By contrast, the number of SMI-34-ir PC dystrophic axonal swellings, termed torpedoes, was significantly greater in AD compared to DS. No differences in SMI-32- and Parv-ir PC OD measurements were observed between groups. Conversely, total number of Parv- (stellate/basket) and Calr (Lugaro, brush, and Golgi)-positive interneurons were significantly reduced in DS compared to AD and HC. A strong negative correlation was found between counts for Parv-ir interneurons, Calr-ir Golgi and brush cells, and Aβ42 plaque load. Number of TrkA and p75NTR positive PCs were reduced in AD compared to HC. These findings suggest that disturbances in calcium binding proteins play a critical role in cerebellar neuronal dysfunction in adults with DS.

The supplementary motor area syndrome and the cerebellar mutism syndrome: a pathoanatomical relationship?

PURPOSE

The supplementary motor area (SMA) syndrome affects adults after tumour resection in SMA neighbouring motor cortex. Cerebellar mutism syndrome (CMS) affects children after tumour resection in the posterior fossa. Both syndromes include disturbances in speech and motor function. The causes of the syndromes are unknown; however, surgical damage to the dentato-thalamo-cortical pathway (DTCP) has been associated with CMS. Thus, an anatomical link between the areas associated with the syndromes is possible. We discuss the syndromes and their possible relationship through the DTCP.

METHODS

We identified 61 articles (cohort studies, case reports and reviews) in MEDLINE and Embase searching for CMS, SMA syndrome or DTCP or synonyms and reviewed for evidence linking CMS and SMA.

RESULTS

We found that SMA syndrome and CMS are similar regarding (1) surgical causation; (2) symptoms including speech impairment, disturbance in motor function and facial dysfunction; (3) delayed onset; (4) the courses of the syndromes are transient; and (5) long-term sequelae are seen in both. Relevant differences include age predominance of adults in SMA syndrome versus children in CMS.

CONCLUSIONS

The similarities of the two syndromes could be traced back to their mutual connection through the DTCP and their membership to a cerebro-cerebellar circuit. The connectivity network could explain the emotional changes and speech reduction in CMS. The difference in time of post-surgical onset may be related to the anatomical distance between the surgical damage to the cerebellum and the SMA, respectively, and the effector neural loop underpinning symptoms.

Cerebellar mutism syndrome: current approaches to minimize risk for CMS

PURPOSE

Cerebellar mutism syndrome (CMS) is a serious source of morbidity following posterior fossa surgery in the pediatric population. However, methods for effectively decreasing its incidence and impact remain unclear. It is our aim to examine the impact of adjusting surgical factors, namely the use of a telovelar approach and avoidance of cavitronic ultrasonic aspirator, on the incidence of CMS in our population as well as outlining potential pre-, intra-, and postoperative factors that may contribute to its development.

METHODS

Retrospective review was performed to identify patients undergoing posterior fossa surgery for resection of a medulloblastoma. Demographic, surgical, and postoperative data were collected. These data were analyzed for possible correlations to the risk of developing CMS via univariate analysis. For factors found to be significant, a multivariate analysis was performed to assess their independence.

RESULTS

Seven of 65 patients (10.8%) developed CMS postoperatively. Factors found to be significantly associated with a higher risk of CMS were the degree of retraction utilized during the procedure (p = 0.0000) and incision of the vermis (p = 0.0294). Although they did not reach the threshold of statistical significance, tumor vascularity (p = 0.19), adoption of a transvermian approach (p = 0.19), and lack of intraoperative imaging (p = 0.17) exhibited strongly suggestive trends towards a correlation with CMS.

DISCUSSION

In an effort to reduce the incidence and severity of CMS in our population, our institution adopted surgical practices that minimize tissue trauma and mitigate postoperative edema. This included the use of a telovelar over a transvermian approach to obviate the need for vermian incision, avoidance of the CUSA, and minimization of heavy retraction during surgery. This was successful in reducing the incidence of CMS from 39% in our medulloblastoma patients to 10.8%. The development of CMS after posterior fossa surgery appears to be a "two-hit" phenomenon requiring a combination of existing predisposition, surgical injury, and postoperative exacerbation. Therefore, it is critical to identify the factors involved at each stage and investigate treatments to target them appropriately.

Pediatric postoperative cerebellar cognitive affective syndrome follows outflow pathway lesions

OBJECTIVE

To evaluate lesion location after pediatric cerebellar tumor resection in relation to the development of severe cognitive and affective disturbances, or cerebellar cognitive affective syndrome (CCAS).

METHODS

The postsurgical lesion location of 195 pediatric patients with cerebellar tumors was mapped onto a template brain. Individuals with CCAS were matched to 2 participants without CCAS by sex, age, and lesion volume. Lesion analyses included both a hypothesis-driven evaluation of the cerebellar outflow pathway (deep nuclei and superior cerebellar peduncles) and data-driven multivariate lesion symptom mapping. Lesion-associated networks were evaluated by comparing connectivity patterns between the lesion location of cases with and those without CCAS with resting-state functional connectivity MRI data from large normative adult and pediatric cohorts.

RESULTS

CCAS was present in 48 of 195 participants (24.6%) and was strongly associated with cerebellar outflow tract lesions (p < 0.0001). Lesion symptom mapping also highlighted the cerebellar outflow pathway, with peak findings in the fastigial nuclei extending into the inferior vermis. Lesion network mapping revealed that the cerebellar region most associated with CCAS was functionally connected to the thalamic mediodorsal nucleus, among other sites, and that higher connectivity between lesion location and the mediodorsal nucleus predicts CCAS occurrence (p < 0.01). A secondary analysis of 27 participants with mutism revealed similar localization of lesions and lesion-associated networks.

CONCLUSION

Lesions of the cerebellar outflow pathway and inferior vermis are associated with major cognitive and affective disturbances after pediatric cerebellar tumor resection, and disrupted communication between the cerebellum and the thalamic mediodorsal nucleus may be important.

The role of radiosurgery in the acute management of fourth ventricle compression due to brain metastases

Background:

Approximately 20–30% of all intracranial metastases are located in the posterior fossa. The clinical evolution hinges on factors such as tumor growth dynamics, local topographic conditions, performance status, and prompt intervention. Fourth ventricle (V4) compression with secondary life-threatening obstructive hydrocephalus remains a major concern, often requiring acute surgical intervention. We have previously reported on the application of adaptive hypofractionated Gamma Knife Radiosurgery in the acute management of critically located metastases, a technique known to us as rapid rescue radiosurgery (3R). We report the results of 3R in the management of posterior fossa lesions and ensuing V4 decompression.

Case Descriptions:

Four patients with V4 compression due to posterior fossa metastases were treated with 3R by three separate gamma knife radiosurgical sessions (GKRS) over a period of seven days. Mean V4 volume was 1.02 cm³ at GKRS 1, 1.13 cm³ at GKRS 2, and 1.12 cm³ at GKRS 3. Mean tumor volume during the week of treatment was 10 cm³ at both GKRS 1 and 2 and 9 cm³ at GKRS 3. On average, we achieved a tumor volume reduction of 52% and a V4 size increase of 64% at the first follow-up (4 weeks after GKRS 3). Long-term follow-up showed continued local tumor control, stable V4 volume, and absence of hydrocephalus.

Conclusion:

For this series, 3R was effective in terms of rapid tumor ablation, V4 decompression, and limited radiation-induced toxicity. This surgical procedure may become an additional tool in the management of intractable posterior fossa metastasis with V4 compression.

Cerebellar Mutism Syndrome After Posterior Fossa Surgery: A Report of Two Cases of Pilocytic Astrocytoma

Cerebellar mutism is a type of syndrome including decreased speech, hypotonia, ataxia and emotional instability which occurs after posterior fossa surgery. It has been first reported by Rekate et al. and Yonemasu in 1985. It is well known that long tract signs and lower cranial nerve involvement are not seen with this syndrome and understanding is preserved. However, the pathophysiology of cerebellar mutism has not been well clarified yet. It is mainly seen in patients with medulloblastoma and brainstem involvement. In this report, we present two extraordinary cases of cerebellar mutism after posterior fossa surgery. They were considered extraordinary because their hystopathological analysis results yielded pilocytic astrocytoma which is out of the predefined risk factors.