Cerebellar mutism

Cerebellar mutism occurs in about 25% of children following posterior fossa tumor surgery. It is usually accompanied by other neurological and behavioral disturbances. Mutism is transient in nature lasting several days to months and is frequently followed by dysarthria. In addition, impairment of language and other neuropsychological functions can be found after long term follow up in the majority of patients. The pathophysiological background of mutism may be higher speech dysfunction mediated by crossed cerebello-cerebral diaschisis which is frequently found during the mute period. Foremost injury to the bilateral dentatothalamocortical tract appears to be critical for the development of cerebello-cerebral diaschisis and subsequent mutism. Direct cerebellar injury is the likely reason for persisting deficits after the mute period. Minimization of injury to the dentatothalamocortical tract during surgery may be promising in the prevention of mutism. While there is no established treatment of mutism, early speech and rehabilitation therapy is recommended.

Dysarthria and mutism

Dysarthria is a speech disorder associated with impairments of intelligibility, smoothness, loudness, and clarity of articulations. Dysarthria involves disability of reproducing various physical, tonal, and sound features of speech sounds in oral speech; unintelligible and slurred articulation with swallowing of sounds is characteristic. Articulatory movements and speech are slow, patients complain to the sensations of a 'thick' tongue and 'porridge' in the mouth. Patients'phrases are constructed correctly, vocabulary is not affected, and the grammatical structure of words is preserved. Reading, writing, internal speech, and understanding of speech are unaffected. Several types of dysarthria have been described on the basis of the lesion locations. Dysarthria can be associated with lacunar syndromes as well. Mutism represents a condition when patient cannot speak and answer the questions, but remains conscious and is able to produce written speech.

A controlled single-case treatment of severe long-term selective mutism in a child with mental retardation

The aim of the present study was to demonstrate the efficacy of combining two operant learning procedures--shaping and fading--for treating selective mutism. The participant was a 12-year-old boy with mental retardation presenting a severe long-term selective mutism. The treatment was aimed at increasing the loudness of his vocalizations in an increasingly social milieu. The treatment was conducted over the course of about 20 weeks, with four 15-minute sessions per week. A gradual increase in speech loudness was observed. Data indicated a close correspondence between the changes in speech loudness and the criteria for reinforcement successively applied by the therapist, thereby confirming the causal link between the child's progress and the changes in reinforcement contingencies. In addition, good generalization was noted during the stimulus fading phase. Six-month follow up showed that loudness of verbalizations was still satisfactory in the classroom despite a change of school and peer group. The impressive improvement of the child's verbal behavior shows that the implementation of a treatment package including both shaping and stimulus fading is a worthwhile therapeutic option, even in the case of severe long-term selective mutism associated with mental retardation.

Speech and language functions that require a functioning Broca's area

A number of previous studies have indicated that Broca's area has an important role in understanding and producing syntactically complex sentences and other language functions. If Broca's area is critical for these functions, then either infarction of Broca's area or temporary hypoperfusion within this region should cause impairment of these functions, at least while the neural tissue is dysfunctional. The opportunity to identify the language functions that depend on Broca's area in a particular individual was provided by a patient with hyperacute stroke who showed selective hypoperfusion, with minimal infarct, in Broca's area, and acutely impaired production of grammatical sentences, comprehension of semantically reversible (but not non-reversible) sentences, spelling, and motor planning of speech articulation. When blood flow was restored to Broca's area, as demonstrated by repeat perfusion weighted imaging, he showed immediate recovery of these language functions. The identification of language functions that were impaired when Broca's area was dysfunctional (due to low blood flow) and recovered when Broca's area was functional again, provides evidence for the critical role of Broca's area in these language functions, at least in this individual.

Postoperative motor speech production in children with the syndrome of 'cerebellar' mutism and subsequent dysarthria: a critical review of the literature

Transient cerebellar mutism is a well-known clinical entity which may develop after surgery to the cerebellum. As the period of mutism is followed by motor speech deficits, the condition has also been termed the syndrome of (cerebellar) Mutism and Subsequent Dysarthria (MSD). In children, its incidence is estimated between 8% and 31%. Unfortunately, the literature provides contradictory information regarding motor speech production post-mutism. We therefore critically reviewed data on 283 childhood cases to chart the mode of recovery of motor speech production after the mute period. After applying stringent exclusion criteria, we found that 98.8% of the children displayed motor speech deficits. This percentage is much higher than commonly reported in the literature. In addition, recovery of speech appeared to be less favourable than previously ascertained. Future studies should investigate more carefully the patients' speech characteristics in order to be able to offer children an adequate and complete rehabilitation program.

Anatomical correlates of early mutism in progressive nonfluent aphasia

Patients with progressive nonfluent aphasia (PNFA) can become mute early in the course of the disease. Voxel-based morphometry showed that PNFA is associated with left anterior insula and inferior frontal atrophy. In PNFA with early mutism, volume loss was more prominent in the pars opercularis and extended into the left basal ganglia. Damage to the network of brain regions involved in both coordination and execution of speech causes mutism in PNFA.

The pathophysiologic mechanism of cerebellar mutism

OBJECTIVE

Cerebellar mutism (CM) is a postoperative complication of mainly pediatric posterior fossa surgery. Multiple theories exist for explaining this phenomenon. We have made an attempt to further understand this entity given a particularly interesting case as it relates to multiple pathophysiologic pathways.

METHODS

We have reviewed the details surrounding a particularly interesting case of CM. A retrospective analysis of this patient's clinical history and recovery is described. An extensive literature review has been performed in conjunction with an attempt to help elucidate details and a better understanding of CM.

RESULTS

A thorough analysis of existing theories as to the pathophysiologic mechanism of CM has been performed as it relates to the details of this particular case. A case is described in which a child exhibiting CM abruptly improved and made a relatively quick recovery after the triggering of the melodic speech pathway by way of watching and beginning to sing along with a video. It appears that this incident involving a familiar song catalyzed various speech pathways, which apparently were in some state of shock. This phenomenon seems to be a temporary entity involving not only the mechanical coordination of speech production, but also the initiation of speech itself.

CONCLUSIONS

Evidence exists for a pathophysiologic pathway for speech by way of coordinating phonation and articulation. In addition, there seems to exist a pathway by which the initiation of speech may be altered or halted by posterior fossa pathology, namely, vermian or dentate nuclear injury. In particular to this case, we found that the incidental appreciation of other forms of speech, melodic in this instance, may be the key to help stimulate and accelerate the recovery from CM.

Suffering in silence: why a developmental psychopathology perspective on selective mutism is needed

A developmental psychopathology perspective is offered in an effort to organize the existing literature regarding the etiology of selective mutism (SM), a relatively rare disorder in which a child consistently fails to speak in 1 or more social settings (e.g., school) despite speaking normally in other settings (e.g., home). Following a brief description of the history, prevalence, and course of the disorder, multiple pathways to the development of SM are discussed, with a focus on the various genetic, temperamental, psychological, and social/environmental systems that may be important in conceptualizing this unusual childhood disorder. The authors propose that SM develops due to a series of complex interactions among the various systems reviewed (e.g., a strong genetic loading for anxiety interacts with an existing communication disorder, resulting in heightened sensitivity to verbal interactions and mutism in some settings). Suggestions are provided for future longitudinal, twin/adoption, molecular genetic, and neuroimaging studies that would be particularly helpful in testing the pathways perspective on SM.

Pure mutism due to simultaneous bilateral lenticulostriate artery territory infarction

A case of pure mutism without pseudobulbar palsy and other neurological findings resulting from simultaneous bilateral lenticulostriate artery territory infarction is presented. A 45-year-old woman suffered a transient ischemic attack with nonfluent aphasia and right hemiparesis. Six months later, she developed pure mutism without oral apraxia, pseudobulbar signs, and motor deficits. Magnetic resonance imaging revealed bilateral infarction in the lentiform nucleus regions. In the available data, there is only one report of simultaneous bilateral lenticulostriate infarction. To date, in all reported cases of mutism of subcortical vascular origin there are also various degrees of pseudobulbar signs and motor deficits and the responsible lesions are mostly consecutive. The case presented here is the first to show pure vascular mutism without other neurological findings.

Long-term effects of transient cerebellar mutism after cerebellar astrocytoma or medulloblastoma tumor resection in childhood

BACKGROUND

Following cerebellar tumor resection, some patients develop transient cerebellar mutism (TCM). Although the mutism resolves, it is not known whether there are long-term motor speech deficits in patients with TCM that are in excess of those in individuals with cerebellar tumors who had not developed postoperative TCM.

METHODS

Long-term survivors of cerebellar tumors resected in childhood who developed TCM were matched to survivors without TCM and to controls. Speech samples were formally analyzed by two speech pathologists.

RESULTS

Tumor survivors who had TCM had significantly more ataxic dysarthric speech and slower speech than either those without TCM or controls and were more dysfluent than controls. Tumor survivors without TCM did not differ from controls on ataxic dysarthria or speech rate.

CONCLUSIONS

Survivors who had TCM showed more speech deficits than controls or survivors without TCM. The data suggest that speech deficits are chronic if not permanent sequelae of TCM.

Cerebellar mutism in adults after posterior fossa surgery: a report of 2 cases

BACKGROUND

Mutism has been associated with injury to midline cerebellar structures secondary to degenerative disease, tumors, hemorrhage, or surgery. Typically, cerebellar mutism syndrome (CMS) has been seen in children and only rarely described in adults after surgery of the posterior fossa. This syndrome typically arises 48 hours after the initiating event and resolves approximately 7 to 8 weeks later. Characteristics of CMS include complete absence of speech without impaired consciousness, other cranial nerve deficits, or long tract signs.

CASE DESCRIPTION

The authors report on 2 patients each of whom developed cerebellar mutism after tumor resection using a posterior fossa approach. The first patient underwent gross total resection of a pineal region tumor via a supracerebellar approach. The second patient underwent posterior fossa decompression for a left cerebellar hemispheric renal cell carcinoma metastasis with adjacent hemorrhage. One patient displayed a variant of cerebellar mutism with severe ataxic dysarthria without complete absence of speech, whereas the other demonstrated frank mutism. After neuroimaging studies confirmed the absence of a surgically treatable postoperative cause for the patients' symptoms, they were managed in a supportive fashion (eg, speech therapy) and improved within 3.5 months and 1 year, respectively.

CONCLUSION

It is paramount that neurosurgeons be aware of cerebellar mutism with regard to its very rare occurrence in adults, its time of onset, and typical self-limiting course.

Reduced auditory efferent activity in childhood selective mutism

BACKGROUND

Selective mutism is a psychiatric disorder of childhood characterized by consistent inability to speak in specific situations despite the ability to speak normally in others. The objective of this study was to test whether reduced auditory efferent activity, which may have direct bearings on speaking behavior, is compromised in selectively mute children.

METHODS

Participants were 16 children with selective mutism and 16 normally developing control children matched for age and gender. All children were tested for pure-tone audiometry, speech reception thresholds, speech discrimination, middle-ear acoustic reflex thresholds and decay function, transient evoked otoacoustic emission, suppression of transient evoked otoacoustic emission, and auditory brainstem response.

RESULTS

Compared with control children, selectively mute children displayed specific deficiencies in auditory efferent activity. These aberrations in efferent activity appear along with normal pure-tone and speech audiometry and normal brainstem transmission as indicated by auditory brainstem response latencies.

CONCLUSIONS

The diminished auditory efferent activity detected in some children with SM may result in desensitization of their auditory pathways by self-vocalization and in reduced control of masking and distortion of incoming speech sounds. These children may gradually learn to restrict vocalization to the minimal amount possible in contexts that require complex auditory processing.

Speech rate as a sticky switch: a multiple lesion case analysis of mutism and hyperlalia

Though it has long been known on the basis of clinical associations and serendipitous observation that speech rate is related to mood and psychomotor baseline, it is less known that speech rate is also related to libido and to immune function. We make the case for a bipolar phenomenon of "psychic tonus," encompassing all these dimensions. The elated, agitated, libidinal, immunofacilitated, and talkative pole is an "approach" disposition primarily activated by the normal left hemisphere-especially, though not exclusively, its frontal lobe. The dejected, lethargic, delibidinized, immunosuppressed, and mute pole is an "avoidance" disposition primarily activated by the normal right hemisphere-especially, though not exclusively, its frontal lobe. In support of this proposed model, we present new evidence, via meta-analysis of previously published single lesion case reports, of a highly significant association between right hemisphere lesions and non-aphasic hyperlalia, and between left hemisphere lesions and non-aphasic mutism.

[Cerebellar mutism syndromes with subsequent dysarthria: a study of three children and a review of the literature]

Cerebellar mutism and subsequent dysarthria (MSD) is a possible complication of posterior fossa surgery. It is usually seen in children after resection of a cerebellar mass lesion. Most patients become mute after a period of (near)normal postoperative speech, and are dysarthric once speech resumes. The pathophysiological mechanisms underlying MSD are most probably multifactorial, combining neuroanatomical, neurophysiological, neuropsychological, and psychological factors. The aim of the present article is to better define the MSD syndrome. The cerebellum is not only involved in motor control. It is also part of a distributed neural circuitry which underlies higher cognitive functions such as, for instance, those associated with the programming of kinetic parameters before motor initiation of a movement. We hypothesize that it could also be involved in the mental initiation which precedes the programming of any intentional bucco-phonatory movements to be performed in order to express oneself.

Mutism after posterior fossa tumour resection in children: incomplete recovery on long-term follow-up

INTRODUCTION

Mutism after posterior fossa tumour resection is generally said to be transient. Our experience suggested that speech did not usually normalise, and that mutism was associated with neurologic deficits that did not recover fully.

METHODS

Children with mutism after posterior fossa tumour resection, and alive more than 2 years post-operatively, were reviewed retrospectively. Charts were reviewed and parents contacted to ascertain details about mutism, associated neurologic deficits, and the most recent speech and neurologic status.

RESULTS

There were 7 children, with follow-up ranging from 2.5 to 13.1 years (mean 6.8 years). Tumours were midline, with 4 astrocytomas and 3 medulloblastomas. Mutism was noted immediately after post-operative extubation in all patients. Speech reappeared 1-15 weeks post-operatively, except for 1 patient, who remained mute at 2.5 years. Speech returned to normal in only 1 patient. Mutism was always accompanied by new or worsened cerebellar ataxia, which resolved incompletely in the long term. Sixth nerve palsies occurred in 3 and recovered incompletely. Seventh nerve paresis occurred in 2 and recovered completely.

CONCLUSION

Mutism after posterior fossa tumour resection is associated with other neurologic deficits, particularly ataxia. Whereas speech usually returns, contrary to general opinion, speech rarely normalises. Other associated deficits rarely resolve completely. These findings have significant implications for counselling of family and patients.

Postoperative speech disorder after medial frontal surgery: role of the supplementary motor area

BACKGROUND

Patients undergoing surgical resection of medial frontal lesions may present transient postoperative speech disorders that remain largely unpredictable.

OBJECTIVE

To relate the occurrence of this speech deficit to the specific surgical lesion of the supplementary motor area (SMA) involved during language tasks using fMRI.

METHODS

Twelve patients were studied using a verbal fluency task before resection of a low-grade glioma of the medial frontal lobe and compared with six healthy subjects. Pre- and postoperative MR variables including the hemispheric dominance for language, the extent of SMA removal, and the volume of resection were compared to the clinical outcome.

RESULTS

Following surgery, 6 of 12 patients presented speech disorders. The deficit was similar across patients, consisting of a global reduction in spontaneous speech, ranging from a complete mutism to a less severe speech reduction, which recovered within a few weeks or months. The occurrence of the deficit was related to the resection of the activation in the SMA of the dominant hemisphere for language (p < 0.01). Increased activation in the SMA of the healthy hemisphere on the preoperative fMRI was observed in patients with postoperative speech deficit.

CONCLUSIONS

fMRI is able to identify the area at risk in the SMA, of which resection is related to the occurrence of characteristic transient postoperative speech disorders. Increased SMA activation in the healthy hemisphere suggested that a plastic change of SMA function occurred in these patients.

The evaluation and comparison of cerebellar mutism in children and adults after posterior fossa surgery: report of two adult cases and review of the literature

BACKGROUND

Although there are some cases of cerebellar mutism in adults after posterior fossa surgery for cerebellar tumour it generally occurs in children. Reversible pathophsiology and the anatomical substrate of this syndrome still remain unclear. The predominance of cerebellar mutism in children is suggested to be related to the higher incidence of posterior fossa tumours in children. However, the question regarding the reason for the obvious difference in the incidence of this syndrome between the paediatric and adult population still remaining unanswered. The aim of this study was to evaluate and compare children and adult groups separately to understand the incidence and the clinical characteristics better and to elucidate the pathophysiological basis and predictive factors for this syndrome.

METHOD

We reviewed, analysed, and compared the cases of cerebellar mutism individually in children and in adults reported in the English literature. We found 106 reported cases in children and 11 cases in adults which were suitable for analysis. We added two adult cases to these.

FINDINGS

The ages of the patients ranged from 2 to 16 (mean, 6.4 year) in children and from 17 to 74 (mean, 38.7 year) in adults. Although vermis was the main location in both groups, the incidence of vermis lesions was considered higher in the paediatric population (%91.5 versus %69.2). The rate of brain stem invasion was prominent in children (%31.1) when compared with adults (%7.6). The latency for the development of mutism and the duration of the mutism were similar in children and adults (mean, 1.4 d versus 2 d and mean, 5.07 wk versus 4.2 wk respectively). Mutism was transient in all the cases of both groups.

INTERPRETATION

Recent concepts of cerebellar physiology disclose the importance of the cerebellum in learning, language, and mental and social functions. Pontine nuclei, the thalamus, motor and sensory areas and supplementary motor areas have been proven necessary for the initiation of speech. It can be hypothesized that uncompleted maturation of the reciprocal links in childhood connecting the cerebellum to these structure makes the children more vulnerable to have postoperative cerebellar mutism in comparison to the adult population.

Non-specific markers of neurodevelopmental disorder/delay in selective mutism--a case-control study

Selective mutism (SM) in children is frequently associated with language disorder/delay suggesting that neurobiological factors may be involved in the development of SM. Motor co-ordination problems, reduced optimality pre- and perinatally and minor physical anomalies represent other markers for neurodevelopmental disorder/delay. The present study explores these markers in referred children with SM (n=54), non-referred matched controls (n =108) and in SM subgroups with and without a communication disorder (CoD). Children with SM differed significantly from controls in parent-reported motor developmental delay, and they obtained a higher pre- and perinatal "reduced optimality score". They scored significantly lower on a motor performance test and showed a higher frequency of minor physical anomalies compared with controls. There were no differences in these respects between SM and CoD compared with SM without CoD. The results confirm that neurobiological factors may be involved in the development of SM. Accordingly, the clinical assessment of referred children with SM should include a thorough history of motor development and an evaluation of present motor skills. The interplay of shyness/social anxiety and motor function problems has to be addressed to reduce misunderstandings of the child's behaviour and to adjust demands for motor skills to the actual level of the child.

Cerebellar mutism associated with a midbrain cavernous malformation. Case report and review of the literature

The authors report a case of cerebellar mutism arising from a hemorrhagic midbrain cavernous malformation in a 14-year-old boy. No cerebellar lesion was identified; however, edema of the dorsal midbrain was noted on postoperative magnetic resonance images. Dysarthric speech spontaneously returned and then completely resolved to normal speech. This case provides further evidence for the theory that involvement of the dentatothalamic tracts, and not a cerebellar lesion per se, is the underlying cause of "cerebellar" mutism.

Mutism: elective or selective, and acquired

When a child does not speak, this may be because there is no wish to do so (elective or selective mutism), or the result of lesions in the brain, particularly in the posterior fossa. The characteristics of the former children are described, especially their shyness; and it is emphasized that mild forms are quite common and a definitive diagnosis should only be made if the condition is significantly affecting the child and family. In the case of mutism due to organic causes, the commonest of these is trauma to the cerebellum. Operations on the cerebellum to remove tumours can be followed by mutism, often after an interval of a few days, and it may last for several months or longer, to be followed by dysarthria. Other rarer causes are discussed, and also the differential diagnosis. The so-called posterior fossa syndrome consists of mutism combined with ataxia, cranial nerve palsies, bulbar palsies, hemiparesis, cognitive impairment and emotional lability, but the post-operative symptoms are often dominated by the lack of speech. The most accepted cause for the condition is vascular spasm with involvement of the dentate nucleus and the dentatorubrothalamic tracts to the brain-stem, and subsequently to the cortex. Diaschisis may be involved in causing the loss of higher cerebral functions, and possibly, complicating hydrocephalus. The treatment of elective mutism is reviewed, either using a psychotherapeutic approach or a variety of drugs, or both. These may well be ineffective, and it must be remembered that the condition often resolves on its own. The former treatment must concentrate on the training of social skills and activities of daily life and must be targeted to both the child, the family, and the school. Also, all kinds of punishment and insistence on speech must be discouraged. The drug, which seems to be most effective, is fluoxetine. Discovering more about the causes of mutism due to organic causes may well depend on studies using such techniques as magnetic resonance imaging and single photon emission tomography.

The role of arousal and "gating" systems in the neurology of impaired consciousness

A brief taxonomy of neurologic disorders resulting in global impairments of consciousness is presented. Particular emphasis is placed on focal injuries of subcortical structures that may produce disorders that are otherwise associated to large bilateral cortical injuries. A distinction between subcortical arousal and "gating" systems is developed. Both clinical and experimental studies are reviewed in the context of these disorders and their possible underlying mechanisms.

Fragile X syndrome and selective mutism

This is the first report that details an association between fragile X syndrome (FXS) and selective mutism (SM). This 12-year-old girl with heterozygous full mutation at FMR1 has a long history of social anxiety and shyness in addition to SM. Her sister also has the full mutation and a history of SM that resolved in adolescence. A beneficial response to fluoxetine and psychotherapy is described. The FMR1 mutation appears to be the first gene mutation associated with SM and further studies are recommended to assess what percentage of patients with SM have the FMR1 mutation.

Episodically remitting akinetic mutism following subarachnoid hemorrhage

Akinetic mutism is characterized by alertness with near complete absence of volitional activity. The authors report a case of episodically remitting akinetic mutism following subarachnoid hemorrhage.

Reversible cerebral perfusion alterations in children with transient mutism after posterior fossa surgery

Mutism is an infrequent and transitory complication observed following posterior fossa surgery. Patients become mute in the immediate postoperative period, with restoration of speech within a few weeks in the absence of additional neurological alterations. The anatomical structures thought to be involved are the connections between the cerebellar dentate nucleus, the ventrolateral nucleus of the contralateral thalamus and the supplementary motor area. In an attempt to understand the pathophysiology of this syndrome, and to depict the perfusion of different brain areas semiquantitatively, in two children who had become mute after posterior fossa surgery we performed a Tc99M-HM-PAO SPECT study during the period of mutism and again when normal speech had returned. In one patient, who had a left cerebellar astrocytoma, the SPECT study showed a marked reduction of cerebral perfusion in the right fronto-parietal region, and in the other, who had a medulloblastoma, a left fronto-temporo-parietal perfusion alteration was observed. When the patients regained normal speech, the follow-up SPECT studies revealed normalization of the cerebral perfusion. This study demonstrates the occurrence of a focal dysfunction of cerebral perfusion in children with cerebellar mutism after posterior fossa surgery. These observations are useful in extending our understanding of the pathophysiology of this postoperative clinical syndrome.

Post-traumatic mutism in children: clinical characteristics, pattern of recovery and clinicopathological correlations

Among the numerous clinical syndromes observed after severe traumatic head injury, post-traumatic mutism is a disorder rarely reported in adults and not studied in any detail in children. We report seven children between the ages of 3 1/2 and 14 years who sustained severe head injury and developed post-traumatic mutism. We aim to give a precise clinical characterization of this disorder, discuss differential diagnosis and correlations with brain imaging and suggest its probable neurological substrate. After a coma lasting from 5 to 25 days, the seven patients who suffered from post-traumatic mutism went through a period of total absence of verbal production lasting from 5 to 94 days, associated with the recovery of non-verbal communication skills and emotional vocalization. During the first days after the recovery of speech, all patients were able to produce correct small sentences with a hypophonic and monotonous voice, moderate dysarthria, word finding difficulties but no signs of aphasia, and preserved oral comprehension. The neurological signs in the acute phase (III nerve paresis in three of seven patients, signs of autonomic dysfunctions in five of seven patients), the results of the brain imaging and the experimental animal data all suggest the involvement of mesencephalic structures as playing a key role in the aetiology of post-traumatic mutism.

Systematic assessment of 50 children with selective mutism

OBJECTIVE

To clarify the diagnostic significance of selective mutism (elective mutism in DSM-III-R).

METHOD

Fifty children with selective mutism were evaluated systematically by means of semistructured clinical interviews and rating scales to obtain detailed diagnostic information.

RESULTS

All 50 children met DSM-III-R criteria for social phobia or avoidant disorder and 24 (48%) had additional anxiety disorders. Clinical measures of anxiety and behavioral symptoms supported the presence of anxiety disorders as a characteristic of selectivity mute children. Only one case each of oppositional defiant disorder and attention-deficit hyperactivity disorder was found.

CONCLUSIONS

Persistent selective mutism typically presents in the context of anxiety disorders.

Akinetic mutism with bithalamic infarction. Neurophysiological correlates

A 42-year-old man presented with akinetic mutism, caused by bilateral thalamic infarction, resulting in a temporary amnesic syndrome and, finally, selective downgaze palsy. Electroencephalographic recording in the initial phase showed generalized spike- and-wave discharges, similar to those found in animal studies after lesion or stimulation of specific thalamic nuclei. Analysis of magnetic resonance images (MRI) of the head showed that the centre of ischemic necrosis particularly involved the intralaminar thalamic nuclei and a small part of the rostral mesencephalon. The findings support the previously suggested involvement of cortico-thalamo-mesencephalic circuitry in the initiation of motor responses, and the association of the non-specific thalamic nuclei with the appearance of generalized epileptiform phenomena in cases of reduced vigilance.

Transient cerebellar mutism after posterior fossa surgery in children

Cerebellar mutism has been reported after surgery for posterior fossa tumors in children and, rarely, in adults. The pathogenesis of this syndrome remains unclear, and controversy exists regarding whether it is a purely psychogenic disorder or an organic syndrome. The anatomical substrate for the mutism also remains unknown. We encountered five cases of postoperative transient cerebellar mutism in a consecutive series of 63 children with posterior fossa tumors. These cases were analyzed and compared with the patients without mutism to find predictive factors for the occurrence of mutism, with the hope of elucidating further the pathophysiological mechanism. The most significant finding was the presence in all cases of a period of cerebellar dysarthria after resolution of the muteness. We, therefore, believe that cerebellar mutism is an extreme form of dysarthria, rather than a real cognitive deficit or a psychological disturbance.

Mutism and pseudobulbar symptoms after resection of posterior fossa tumors in children: incidence and pathophysiology

MUTISM AND A variety of other neurobehavioral symptoms have been reported anecdotally after the removal of posterior fossa mass lesions. To determine the incidence and clinical spectrum of this syndrome, a detailed review was performed of patients undergoing resection of infratentorial tumors at our institution during the last 9 years; 12 of 142 patients (8.5%) manifested this syndrome, the largest series of such patients reported to date. Each child had a lesion that involved the vermis; seven had medulloblastomas, three had astrocytomas, and two had ependymomas. The incidence among children with vermian neoplasms was 13%. Ten children underwent division of the inferior vermis during tumor resection, and three had a superior vermian incision; one child underwent both superior and inferior vermian incisions. In 10 children, mutism developed in a delayed fashion postoperatively. The speech disturbance was associated with poor oral intake in 9 children, urinary retention in 5, long-tract signs in 6, and bizarre personality changes, emotional lability, and/or decreased initiation of voluntary movements in all 12. Neuropsychiatric testing, performed in seven children, confirmed impairments not only in speech but also in initiation of other motor activities. Ten children regained normal speech, bladder control, and neurological functioning, other than ataxia and mild dysarthria, within 1 to 16 weeks; two children had significant residual deficits. Characteristically, affect and oral intake returned to their preoperative baseline before the speech difficulties began to resolve. A detailed radiological review of these cases in parallel with 24 cases of vermian tumors without mutism identified only one factor that was significantly associated with the mutism syndrome, bilateral edema within the brachium pontis (P < 0.01). Neither the size of the tumor nor the length of vermian incision was associated with the development of mutism. The clinical features of this syndrome in the context of these imaging findings suggest that the mutism syndrome results from transient impairment of the afferent and/or efferent pathways of the dendate nuclei that are involved in initiating complex volitional movements. The clinical courses of our patients are presented and compared with those of similar cases in the literature in an attempt to evaluate the validity of this hypothesis.

[Mutism and aphasia--a review of the literature]

Mutism in the sense of a complete inability to produce oral language is a rare symptom in aphasic disorders and most often occurs as a transient initial sign. Among the pathomechanisms causing muteness in aphasia, disturbances of speech initiation and of limbic aspects of speech production on the one hand and speech motor programming impairments on the other are considered. This article reviews clinical reports of extremely reduced speech or complete muteness in the context of aphasia, discussing the observed symptom patterns as well as their neuroanatomic correlates and aspects of their recovery.

[Mutism in central motor disorders--a review of the literature]

Mutism can be defined as "a condition in which there is no, or very little, oral-verbal expression, whereas comprehension of speech ... is normal or at least at a considerably higher level" (Lebrun, 1990). Benson (1979) enumerates five neuroanatomical correlates of mutism: (a) damage to the Broca region, (b) lesion of the supplementary motor area of the dominant hemisphere, (c) dysfunction of the mesencephalic reticular system, (d) thalamotomy, and (e) bilateral pathology of cortical and subcortical motor structures. The last item refers to syndromes of mutism resulting from central motor disorders. Depending on location and size of the lesion this pathophysiological interpretation should hold true for the fourth point as well. In mutism due to central motor disturbances lacking verbal expression represents the most severe degree of dysarthria, i.e. anarthria. The present review provides a detailed description of mutism following corticobulbar, striatal, and cerebellar dysfunctions.

Post-traumatic mutism

We report on the infrequent verbalisation disorder called "post-traumatic mutism" observed in 12 subjects with severe traumatic head injuries. These patients during the recovery of their conditions showed for a certain period a speechlessness even though some of them could communicate through gestures and writing. The nature and the possible mechanism of the disorder are discussed.

Transient "cerebellar" mutism in lesions of the mesencephalic-cerebellar region

Four patients aged from 20 to 48 years with transient mutism are presented: 3 patients underwent surgery for midline tumours of the mesencephalic-cerebellar region (medulloblastoma in two cases and pinealoblastoma in one), at times attached to one or both lateral recesses of the IV ventricle. One patient was hospitalized and treated for brain-stem ischemia. All patients developed mutism 48 to 72 hours after surgery; in the patient with brain-stem softening mutism appeared 72 hours after admission. All the patients had unimpaired consciousness and no deficits of lower cranial nerves. Speech, always normal in the first hours after surgery, was regained after a period of 6-16 weeks. Various hypotheses for this speech disorder are analyzed.

Mechanism of mutism following the transcallosal approach to the ventricles

Transient mutism has been known as a common manifestation following callosotomy for medically intractable epilepsy, but its cause has not been clearly elucidated. In this paper, we report three cases of mutism following a transcallosal approach to tumours in the lateral and third ventricles and retrospectively analyze the surgical, neurological and radiological features which may suggest the cause of this type of mutism. Mutism may be a result of division of the corpus callosum. Suppression of the limbic system caused by lesions in the anterior cingulate gyrus, septum pellucidum, and fornix may have been of importance in at least two of these three cases. Impairments of the supplementary motor cortex, thalamus and basal ganglia may also be factors reducing speech production. The mechanism of such transient mutism seems to be a complex of two or more of these factors, and their combinations may be different from one case to the other.

Transient mutism following removal of a cerebellar tumor. A case report and review of the literature

A 14-year-old boy developed mutism 24 h after the removal of a vermian low-grade astrocytoma. The mutism was not accompanied by long tract signs or cranial nerve palsies. He started to regain his speech 3 weeks postoperatively, and 4 months after the operation he was minimally dysarthric. Seven similar cases of transient muteness following cerebellar operations and not accompanied by long tract signs or cranial nerve palsies have been reported in the literature. In most of them there was delayed postoperative onset of the mutism. In all patients the recovery of speech started to appear 2 weeks to 3 months postoperatively and passed through a dysarthric phase. The absence of long tract or other brain stem signs, together with the presence of dysarthria during the recovery of speech, suggests a cerebellar cause for the transient muteness.

Functions of the corpus callosum: observations from callosotomy performed for intractable epilepsy

The effects of complete and partial corpus callosotomy in 6 patients are reported. Only the 2 cases undergoing total callosotomy showed evidence of impaired interhemispheric sensory transfer, related to sectioning of the splenium. Only mild long-lasting neuropsychological deficits were detected. Post-commissurotomy mutism and akinesia appeared in 4 cases, 2 with total, and 2 with partial anterior callosotomy. The short-and long-term effects of corpus callosotomy appear to be related to the extent of the section the creation of lesions during the surgical procedure, and a peculiar organization of cognitive functions in chronic epileptic patients.

Cognitive dysfunction, negative symptoms, and tardive dyskinesia in schizophrenia. Their association in relation to topography of involuntary movements and criterion of their abnormality

Little is known of factors that, on an individual basis, confer vulnerability to the emergence of involuntary movements (tardive dyskinesia) during long-term neuroleptic treatment. In this study of 88 chronic schizophrenic inpatients, 22 variables (four demographic, 14 medication history, and four features of illness) were compared for any association(s) with the presence, by differing topographies and criteria of abnormality, and severity of involuntary movements. Irrespective of the criterion used, the presence of marked cognitive dysfunction-muteness bore a consistent and highly significant primary association with both the presence and the overall severity of orofacial dyskinesia; no such association was found in relation to the presence of limb-truncal dyskinesia. Flattening of affect was the only other variable consistently associated with the presence of orofacial movements. The reliability and prominence of the association between the presence of orofacial, but not of limb-truncal, movements and cognitive dysfunction-negative symptoms suggest that these varying topographies may not constitute a unitary syndrome. This strong association, not with indexes of neuroleptic exposure but rather with features of the illness for which that treatment was prescribed, suggests some neurologic process, more subtle than may previously have been appreciated, as a vulnerability factor of some importance. In schizophrenia it appears to be intimately related to the disease process.

Hyperkinetic mutism: bilateral ballism and basal ganglia calcification

We studied a 70-year-old woman with a unique combination of hyperkinesia and mutism. These findings differed from akinetic mutism because there was continuous bilateral ballism and dystonia--hence the term "hyperkinetic mutism." CT demonstrated bilateral calcifications in the basal ganglia, and MRI indicated bilateral watershed infarcts. Different dopaminergic mechanisms may underlie the hyperkinesia and mutism.

Reversible "locked-in" syndromes

Two young patients are described who made good recoveries from a "locked-in" syndrome presumed to be due to ventral pontine ischemia. The first patient recovered completely from quadriplegia and mutism. In the second patient the only permanent sequellae were slight dysarthria and mild spasticity. Since patients may recover nearly completely from a "locked-in" syndrome, aggressive supportive therapy seems justified during the initial weeks or months.

Mutism: loss of neocortical and limbic vocalization

A patient with complete mutism of 5 years duration was studied to determine the cause of the defective phonation. The patient had neurological findings indicative of pseudobulbar palsy, but he had lost emotional vocalization and emotional facial expression, as well as propositional speech. Phylogenetic, ontogenetic, and anatomic evidence indicates that propositional speech and volitional facial movements are mediated by corticobulbar tracts descending from neocortical areas, whereas emotional vocalization and emotional facial expression are dependent on intact limbic system connections. The findings suggest that the patient's impaired faciovocal expression was the result of lesions involving both limbic system and descending neocortical connections.

Motor aphasia unaccompanied by faciobrachial weakness

Most patients with motor aphasia resulting from lesions of the left frontal opercular region have weakness of the right face and arm. We report a 43-year-old man who suffered mutism and agraphia unaccompanied by right-sided weakness after embolic infarction of Broca's area.