Cerebellar mutism (CM) was first described by Rekate et al. in 1985 following posterior fossa surgery in children 1) ;since then, it has increasingly been reported, mainly occurring as a postoperative complication. It has also been reported in both children and adults following several other cerebellar insults, including vascular events, infections and trauma 2).
Pitsika et al., The PubMed database was searched using the term cerebellar mutism and relevant definitions to identify publications in the English-language literature. Pertinent publications were selected from the reference lists of the previously identified articles. Over the last few years an increasing number of prospective studies and reviews have provided valuable information regarding the cerebellar mutism syndrome. Importantly, the clarification of principal terminology that surrounds the wide clinical spectrum of the syndrome results in more focused research and more effective identification of this entity. In children who undergo surgery for medulloblastoma the incidence of cerebellar mutism syndrome was reported to be 24%, and significant risk factors so far are brainstem involvement and midline location of the tumor. The dentate-thalamo-cortical tracts and lesions that affect their integrity are considered significant pathophysiological issues, especially the tract that originates in the right cerebellar hemisphere. Moderate and severe forms of the cerebellar mutism syndrome are the most frequent types during the initial presentation, and the overall neurocognitive outcome is not as favorable as thought in the earlier publications. Advanced neuroimaging techniques could contribute to identification of high-risk patients preoperatively and allow for more effective surgical planning that should focus on maximal tumor resection with minimal risk to important neural structures. Properly designed multicenter trials are needed to provide stronger evidence regarding effective prevention of cerebellar mutism and the best therapeutic approaches for such patients with a combination of pharmacological agents and multidisciplinary speech and behavior augmentation 3).
Posterior fossa syndrome (PFS) and cerebellar mutism are often used interchangeably in the literature.
The uncertain aetiology of PFS, myriad of cited risk factors and therapeutic challenges make this phenomenon an elusive entity.
The pathophysiology of this condition remains unclear, but there is evidence implicating surgical injury of the proximal efferent cerebellar pathway (pECP) and the cerebellar vermis to PFS.
Chua et al., performed a clinical study that evaluated possible risk factors for permanent PFS in paediatric medulloblastoma patients. Analysis of collated results found that post-operative DWI restriction in bilateral regions within the surgical cavity demonstrated statistical significance as a predictor of PFS permanence-a novel finding in the current literatura 5).
Children who receive treatment for medulloblastoma have a high survival rate, but also a high likelihood of developing posterior fossa syndrome.
Diffusion abnormalities were identified in 10 cases, 7 of which involved the proximal efferent cerebellar pathway (pECP). Retrospective evaluation revealed evidence of PFS in 6 cases. There was a significant association between abnormalities involving pECP structures (P = .001) and development of PFS. Bilateral involvement of pECP (P = .006) was a highly specific risk factor for predicting the development of PFS. Diffusion abnormality of the inferior vermis was significantly associated with PFS (P = .001) but may not represent a risk factor in isolation 6).
This syndrome involves a variety of signs and symptoms including cerebellar mutism or speech disturbances, dysphagia, decreased motor movement, cranial nerve palsy and, emotional lability. These signs and symptoms develop from an average range of 24 to 107 hours after surgery and may take weeks to months to resolve.
Early recognition of this syndrome could facilitate preventive and restorative patient care, prevent subsequent complications, decrease length of hospital stays, and promote patient and family understanding of and coping with the syndrome 7).
20 cases of PFS (8%), 12 males and 8 females. Age ranged from 1.5 to 13 years (mean = 6.5). Of the 20, 16 were medulloblastoma, 3 ependymoma and 1 astrocytoma. There was a 21 % incidence (16/76) of PFS in medulloblastoma of the posterior fossa. The incidence for ependymoma was 13% (3/24) and 1% (1/102) for astrocytoma. All 20 cases (100%) had brainstem involvement by the tumor. The most frequent postoperative findings included mutism, ataxia, 6th and 7th nerve palsies and hemiparesis. Mutism had a latency range of 1-7 days (mean = 1.7) and a duration of 6-365 days (mean = 69.2, median = 35). Although mutism resolved in all cases, the remaining neurologic complications which characterized our findings of PFS were rarely reversible. We describe potential risk factors for developing PFS after surgery with hopes of making neurosurgeons more aware of potential problems following the removal of lesions in this area. Early recognition of PFS would further promote patient and family understanding and coping with this síndrome 8)
19 children diagnosed with posterior fossa syndrome 9)
Nedermeijer et al. describe a girl with late onset OCT deficiency presenting with transient mutism and subsequent dysarthria, ataxia and behavioural changes. This is an exceptional report of a not yet described neurologic syndrome in Ornithine transcarbamylase deficiency (OTC) 11).
De Smet report an adult patient with PFS after surgical evacuation of a cerebellar bleeding. After 45 days of (akinetic) mutism, the patient's cognitive and behavioural profile closely resembled the “cerebellar cognitive-affective syndrome”. A quantified SPECT study showed perfusional deficits in the anatomoclinically suspected supratentorial areas, subserving language dynamics, executive functioning, spatial cognition and affective regulation. We hypothesize that cerebello-cerebral diaschisis might be an important pathophysiological mechanism underlying akinetic mutism, cognitive deficits and behavioural-affective changes in adult patients with PFS 12).
A 12-year-old child who developed transient cerebellar mutism associated with behavioral and emotional symptoms following rupture of a vermis arteriovenous malformation (AVM). Following the stroke, the girl experienced a 24-hour symptom-free interval. After that, she became mute and her emotional state was characterized by severe anxiety, irritability and withdrawal. After 3 days, mutism resolved and dysarthria became apparent. Two weeks after stroke, the AVM was surgically removed and the postoperative course was uneventful. This case is the first reported in which the PFS occurred after focal nonsurgically induced cerebellar damage 13).
Cerebellar mutism is a rare occurrence following paediatric trauma 14) 15) 16) 17). , this phenomenon has rarely been reported following other insults, such as trauma, and its pathophysiology remains poorly understood.
A seven-year-old child who presented to the casualty department of Sultan Qaboos University Hospital in Muscat, Oman, in May 2013 with a traumatic right cerebellar contusion. The child presented with clinical features of cerebellar mutism but underwent a rapid and spontaneous recovery 18).