Cerebellar Mutism Syndrome After Posterior Fossa Tumor Surgery in Children-A Retrospective Single-Center Study

Medical management of cerebellar mutism syndrome at a quaternary children's hospital

PURPOSE

We aimed to evaluate the efficacy of selective serotonin reuptake inhibitors (SSRIs) in treating cerebellar mutism syndrome (CMS).

METHODS

We retrospectively reviewed all pediatric patients who underwent a posterior fossa tumor resection between May 2007 to September 2022 at a single quaternary pediatric hospital. We evaluated clinical presentation and hospital course, including imaging findings, pathology, and surgical approaches. Propensity score matching was used to compare the symptom duration of patients who received SSRIs versus those who did not.

RESULTS

A total of 292 patients met the criteria with 25% (n = 73) being diagnosed with CMS. Several factors were significantly associated with a CMS diagnosis, such as pre-operative hydrocephalus (p = 0.002), a vermis-splitting approach (p = 0.007), tumor in the fourth ventricle (p = 0.010), medulloblastoma diagnosis (p = 0.009), and postoperative complication (p < 0.001). Of the patients diagnosed with CMS, 32.9% (n = 24) received SSRI treatment, specifically fluoxetine (n = 18) and sertraline (n = 6). Overall, treatment did not decrease the duration of CMS symptoms or shorten the inpatient rehab course compared to matched controls. However, within the cohort of fluoxetine-treated patients, earlier initiation of medication was significantly correlated with a shorter duration of mutism (p = 0.007).

CONCLUSIONS

We report the largest cohort of CMS patients treated with SSRIs. The lack of overall clinical benefit when compared to untreated patients in our study may be due to the length of delay in starting an SSRI, since early initiation of fluoxetine correlated with shorter CMS symptoms. These results support the importance of early clinical detection of CMS and potentially treating CMS early in the patient's postoperative course.

Neuroimaging of postoperative pediatric cerebellar mutism syndrome: a systematic review

Background

Postoperative pediatric cerebellar mutism syndrome (ppCMS) poses serious morbidity after posterior fossa tumor surgery. Neuroimaging studies aim to understand its pathophysiology, yet these vary in methodology and outcome measures. Therefore, we systematically reviewed the current literature to evaluate the evidence for differences in neuroimaging features between children with and without ppCMS.

Methods

Following PRISMA guidelines, a systematic review was conducted by searching for original articles on neuroimaging in children undergoing posterior fossa tumor surgery, comparing patients with and without ppCMS. Articles were selected based on predefined eligibility criteria. Data were systematically extracted, and risk of bias was evaluated.

Results

From the 866 articles identified, 50 studies fulfilled the inclusion criteria. Studies were categorized into 3 imaging domains: structural, diffusion, and functional imaging. Risk of bias assessment revealed a medium risk in most articles, predominantly due to unclear ppCMS definition and qualitative image analysis without blinding for ppCMS diagnosis. Preoperative structural imaging showed the association of ppCMS with midline tumor localization and involvement of the brainstem, superior cerebellar peduncle (SCP), or middle cerebellar peduncle. Postoperative structural and diffusion imaging highlighted SCP injury with reduced white matter integrity, while functional imaging demonstrated hypoperfusion in frontal lobes. Late follow-up showed T2-weighted hyperintensities in the inferior olivary nuclei of ppCMS patients.

Conclusion

Neuroimaging features suggest that ppCMS is associated with efferent cerebellar pathway injury and hypoperfusion in frontal lobes, with level 2 a/b evidence. Large-scale prospective longitudinal neuroimaging studies comparing pre- and postoperative imaging are needed to further elucidate the pathophysiological mechanism of ppCMS.

National multicentered retrospective review of clinical and intraoperative factors associated with the development of cerebellar mutism after pediatric posterior fossa tumor resection

BACKGROUND

Cerebellar mutism (CM) is characterized by a significant loss of speech in children following posterior fossa (PF) surgery. The biological origin of CM remains unclear and is the subject of ongoing debate. Significant recovery from CM is less likely than previously described despite rigorous multidisciplinary neuro-rehabilitational efforts.

METHODS

A national multi-centered retrospective review of all children undergoing PF resection in four midsized Canadian academic pediatric institutions was undertaken. Patient, tumor and surgical factors associated with the post-operative development of CM were reviewed. Retrospective identification of PF surgery patients including those developing and those that did not (internal control).

RESULTS

The study identified 258 patients across the 4 centers between 2010 and 2020 (mean age 6.73 years; 42.2% female). Overall, CM was experienced in 19.5% of patients (N = 50). Amongst children who developed CM histopathology included medulloblastoma (35.7%), pilocytic astrocytoma (32.6%) and ependymoma (17.1%). Intraoperative impression of adherence to the floor of the 4th ventricle was positive in 36.8%. Intraoperative abrupt changes in blood pressure and/or heart rate were identified in 19.4% and 17.8% of cases. The clinical resolution of CM was rated to be complete, significant resolution, slight improvement, no improvement and deterioration in 56.0%, 8.0%, 20.0%, 14.0% and 2.0%, respectively. In the cohort of children who experienced post-operative CM as compared to their no-CM counterpart, proportionally more tumors were felt to be adherent to the floor of the 4th ventricle (56.0% vs 49.5%), intraoperative extent of resection was a GTR (74% vs 68.8%) and changes in heart rate were noted (≥ 20% from baseline) (26.0% vs 15.9%). However, a multiple regression analysis identified only abrupt changes in HR (OR 5.97, CI (1.53, 23.1), p = 0.01) to be significantly associated with the development of post-operative CM.

CONCLUSION

As a devastating surgical complication after posterior fossa tumor surgery with variable clinical course, identifying and understanding the operative cues and revising intraoperative plans that optimizes the child's neurooncological and clinical outcome are essential.