Postoperative cerebellar mutism in adult patients with Lhermitte-Duclos disease

Cerebellar mutism (CM) is a rare and severe form of speech and language impairment, mostly diagnosed in children and adolescents and rarely reported in adults. We here review the literature and summarize all anatomical structures related to the pathogenesis of this rare syndrome. We also report two illustrative cases of CM following surgical treatment of Lhermitte-Duclos disease (LDD; dysplastic gangliocytoma) in two adult patients. LDD is a rare benign cerebellar tumor. Surgical excision appears to be the only effective treatment. However, surgery is hampered by the difficulty to distinguish between tumor and healthy cerebellar tissue, which may result in extensive resection and cause neurological deficits such as CM. A review of the literature and our two cases suggest that lesions or functional impairment of paravermian structures including dentate nuclei, vermis, lateral hemispheres, and cerebellocortical pathways contribute to the development of CM. However, there is no single anatomical structure identified to be associated with CM. It is unknown whether some diseases such as LDD carry a higher risk of postoperative CM than others. As illustrated by our two cases, although there are no special means, optimal preoperative diagnosis might contribute to the prevention of this syndrome. Despite the severity, CM carries a favorable prognosis and generally resolves within a few months. To conclude, we review the clinical signs and particularly the pathophysiological observations and anatomical structures affected in the development of postoperative CM and contribute two cases illustrating the pathogenesis, prognosis, and possible prevention of this syndrome, to focus that CM might also occur in adults even in association with rare tumors.