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 speech: Out of all of the symptoms of the post-operative pediatric CMS, speech tends to be the last thing to recover . 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 . 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 . 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 , and outcome is generally poorer for children with right-sided tumors and/or medulloblastomas compared to those with left-sided tumors and/or astrocytomas . 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) , 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 . 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 . Several years later, many still suffer from decrements in full-scale IQ, verbal comprehension, perceptual reasoning, memory and processing speed , 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.
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