Recovery of CM is spontaneous but rarely complete, and the same goes for many other symptoms of the post-operative pediatric CMS. It is difficult to predict the prognosis for the individual patient, and the course of recovery is extremely variable. Some recover fully, others are left with long-term sequelae in the form of e.g. dysarthria, ataxia, reduced IQ and persistent psycho-social problems [1, 2].


Neurological/motor problems: At 1-2 months post-operatively 85-100% of patients suffer from ataxia, nystagmus, dysmetria and tremor, around 50% have hypotonia and 40% oculomotor deficits. While many of the post-operative neurological/motor problems reverse, ataxia, poor balance and 6th cranial nerve palsy (cross-eyed-ness) often linger on [3, 4, 5, 6, 7, 8].

Mutism and speechOut of all of the symptoms of the post-operative pediatric CMS, speech tends to be the last thing to recover [9]. It always returns - sometimes back to normal, sometimes not - and in a review from 2001, 68% of patients were still suffering from motor speech deficits 1 year post-operatively [10].  There is a significant correlation between the severity of neurological symptoms and duration of mutism post-operatively; the more severe the neurological symptoms, the longer the duration of mutism [9]. According to recent studies the most common features of speech upon recovery are distorted vowels, slowed speech an prolonged phonemes, reduced verbal output with short phrases, monopitch/monoloudness, hypernasality, vocal tremor and dysarthria [9, 11, 12, 13]. There seems to be a high association between dysarthria and dysphagia in children [12], and outcome is generally poorer for children with right-sided tumors and/or medulloblastomas compared to those with left-sided tumors and/or astrocytomas [13]. Dysarthria is frequently a permanent sequela of cerebellar mutism [14, 15, 5].

Language: Language disorders have not been thoroughly investigated in this patient population, but impaired verbal fluency, word-finding difficulties and grammatical disturbances have been described up to 6 months post-operatively (17). They may last much longer.

Neuropsychological outcome - behavioral/affective aspect: Many patients suffer from depression, irritability, apathy and inattention post-operatively, and onset is accompanied by new/worsening neurological signs (ataxia, paresis, oculomotor dysfunction, reduced facial expression and incontinence). Acute affective/behavioral symptoms last up to 2 months, and tend to resolve before the mutism does. There is a significant correlation between age and duration of acute symptoms; the older the child, the longer the duration [18, 9].  Some problems can persist, and obsessive-compulsive behavior, withdrawal, social and internalizing problems, depression, anxiety and lability have been described at 1-2 years post-operatively [5, 19). They may last much longer.

Neuropsychological outcome - cognitive aspect: Cognitive outcome may be affected by tumor type, location and adjuvant therapy. Children with medulloblastoma (treated with surgery, radiotherapy and chemotherapy) fare worse than those with astrocytoma (treated with surgery alone) [20], and injuries to the vermis and dentate nuclei predict poor neurological and neuropsychological outcome in children with malignant posterior fossa tumors in general (and not post-operative pediatric CMS patients per se). This same group of patients has been shown to have reduced IQ up to 5-6 years post-operatively [21]. One year post-operatively, most patients affected by the post-operative pediatric CMS suffer from slow processing speed, attention and executive problems, difficulty with reading, writing and mathematics, reduced general intellectual ability and poor academic achievement compared to healthy controls [22]. Several years later, many still suffer from decrements in full-scale IQ, verbal comprehension, perceptual reasoning, memory and processing speed [18], and up to 60% may need special education [17,  23, 8]. Thus even after having been cured from their brain tumor, the post-operative pediatric CMS and its consequences represent one of the greatest challenges that many of the affected children are faced with for the rest of their lives.

Links to:

Definitions, Incidence, Symptoms, Anatomy, Pathophysiology, Imaging findings, Risk factors, Treatment, Prevention

1. Gudrunardottir T, Sehested A, Juhler M, Schmiegelow K (2011) Cerebellar mutism : Review of the literature. Childs Nerv Syst

2. Gudrunardottir T, Paquier P, Bartha-Döring L, Mariën P. Cerebellar mutism and the posterior fossa syndrome. Chapther in: The Linguistic Cerebellum. Elsevier 2015 (in press)

3. Juhler M. Ataxia and poor balance often linger on after PF surgery. Personal Communication

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13. Morgan AT, Liegeois F, Liederkerke C, Vogel AP, Hayward R, Harkness W, Chong K, Vargha-Khadem F (2011) Role of cerebellum in fine speech control in childhood: persistent dysarthria after surgical treatment for posterior fossa tumour. Brain Lang 117: 69-76

14. Aarsen FK, van Dongen HR, Paquier PF, van MM, Catsman-Berrevoets CE (2004) Long-term sequelae in children after cerebellar astrocytoma surgery. Neurology 62: 1311-1316

15. Huber JF, Bradley K, Spiegler BJ, Dennis M (2006) Long-term effects of transient cerebellar mutism after cerebellar astrocytoma or medulloblastoma tumor resection in childhood. Childs Nerv Syst 22: 132-138

16. Steinbok P, Cochrane DD, Perrin R, Price A (2003) Mutism after posterior fossa tumour resection in children: incomplete recovery on long-term follow-up. Pediatr Neurosurg 39: 179-183

17. De Smet HJ, Baillieux H, Wackenier P, De PM, Engelborghs S, Paquier PF, De Deyn PP, Marien P (2009) Long-term cognitive deficits following posterior fossa tumor resection: a neuropsychological and functional neuroimaging follow-up study. Neuropsychology 23: 694-704

18. Beckwitt TS, Krieger MD, O'Neil S, Jubran R, Tavare CJ (2012) Symptoms before and after posterior fossa surgery in pediatric patients. Pediatr Neurosurg 48: 21-25

19. Wolfe-Christensen C, Mullins LL Scott JG, McNall-Knapp RY (2007) Persistent psychosocial problems in children who develop posterior fossa syndrome after medulloblastoma resection. Pediatr Blood Cancer 15;49(5): 723-6.

20. Rønning C, Sundet K, Due-Tønnessen B, Lundar T, Helseth E (2005). Persistent Cognitive Dysfunction Secondary to Cerebellar Injury in Patients Treated for Posterior Fossa Tumors in Childhood. Pediatr Neurosurg 41: 15–21

21. Puget S, Boddaert N, Viguier D, Kieffer V, Bulteau C, Garnett M, Callu D, Sainte-Rose C, Kalifa C, Dellatolas G, Grill J (2009) Injuries to inferior vermis and dentate nuclei predict poor neurological and neuropsychological outcome in children with malignant posterior fossa tumors. Cancer 115: 1338-1347

22. Palmer SL, Hassall T, Evankovich K, Mabbott DJ, Bonner M, Deluca C, Cohn R, Fisher MJ, Morris EB, Broniscer A, Gajjar A (2010) Neurocognitive outcome 12 months following cerebellar mutism syndrome in pediatric patients with medulloblastoma. Neuro Oncol 12: 1311-1317

23. Turkel SB, Shu CL, Nelson MD, Hyder D, Gilles FH, Woodall L et al (2004) Case series: acute mood symptoms associated with posterior fossa lesions in dhildren. J Neuropsychiatry Clin Neurosc 16: 443-445