Emotional Lability as a Symptom of Extra-axial Posterior Fossa Tumors: A Case-Control Review of Neuroanatomy and Patient-Reported Quality of Life

Introduction: Emotional lability (EL), the uncontrollable and unmotivated expression of emotion, is a rare and distressing symptom of brainstem compression. In published case reports, EL from an extra-axial posterior fossa tumour was alleviated by tumour resection. The primary aim herein was to radiographically establish the degree of compression from mass lesions onto brainstem structures.Secondarily, we compared changes in patient-reported quality of life (QOL) pre- and post-operatively. Methods: Retrospective review of posterior fossa tumours treated between 2002-2018 at Vancouver General Hospital revealed 11 patients with confirmed EL. Each case was matched to 3 controls. A lateral brainstem compression scale characterized mass effect at the level of the medulla, pons, and midbrain in pre-operative axial T2-weighted FLAIR MRI scans. Compression and clinical variables were compared between patient groups. Short form-36 (SF36v1) health surveys were retrospectively obtained from patient charts to compare pre- versus post-operative changes in survey scores between EL and control patients. Results: EL symptoms ceased post-operatively for all EL patients. EL tumours exert greater compression onto the pons (p=0.03) and EL patients more commonly have cerebellar findings pre-operatively (p=0.003). Patients with EL-causing tumours experienced greater improvement post-operatively in “Health Change” (p=0.05), which was maintained over time. Conclusion: Findings suggest that compression onto the pons inhibits control over involuntary, stereotyped expression of emotion. This adds to evidence that EL may be attributed to cerebellum deafferentation from cortical and limbic structures through the basis pontis, leading to impaired modulation of emotional response. QOL results augment benefits of obtaining EL-alleviating tumour resections.