Clozapine-induced stuttering and seizures

Drug-induced stuttering: A comprehensive literature review

Drug-induced stuttering (DIS) is a type of neurogenic stuttering (NS). Although DIS has not been reported as frequently as other cases of NS in the literature, it is not a negligible adverse drug reaction (ADR) which can significantly affect the quality of life if not treated. This literature review aims to evaluate the epidemiological and clinical characteristics of DIS and suggests some pathophysiological mechanisms for this ADR. Relevant English-language reports in Google Scholar, PubMed, Web of Science, and Scopus were identified and assessed without time restriction. Finally, a total of 62 reports were included. Twenty-seven drugs caused 86 episodes of stuttering in 82 cases. The most episodes of DIS were related to antipsychotic drugs (57%), mostly including clozapine, followed by central nervous system agents (11.6%) and anticonvulsant drugs (9.3%). The majority of the cases were male and between the ages of 31 and 40 years. Repetitions were the most frequent core manifestations of DIS. In 55.8% of the episodes of DIS, the offending drug was withdrawn to manage stuttering, which resulted in significant improvement or complete relief of stuttering in all cases. Based on the suggested pathophysiological mechanisms for developmental stuttering and neurotransmitters dysfunctions involved in speech dysfluency, it seems that the abnormalities of several neurotransmitters, especially dopamine and glutamate, in different circuits and areas of the brain, including cortico-basal ganglia-thalamocortical loop and white matter fiber tracts, may be engaged in the pathogenesis of DIS.

Clozapine-induced stuttering in the absence of known risk factors: a case report

Background

Stuttering is a rare side effect of clozapine. It has been shown to occur in the presence of one or more factors such as abnormal electrophysiological findings and seizures, extrapyramidal symptoms, brain pathology, and a family history of stuttering. Few case reports have documented the occurrence of clozapine-induced stuttering in the absence of these risk factors.

Case presentation

A 29-year-old African male on clozapine for treatment-resistant schizophrenia presented with stuttering at a dosage of 400 mg/day that resolved with dose reduction. Electroencephalogram findings were normal, and there was no clinical evidence of seizures. The patient had no prior history or family history of stuttering, had a normal neurological examination, and showed no signs of extrapyramidal symptoms.

Conclusion

Clinicians ought to be aware of stuttering as a side effect of clozapine, even in the absence of known risk factors. Further research should investigate the pathophysiology of clozapine-induced stuttering.

Drug induced stuttering: pharmacovigilance data

Background: Stuttering is a speech disorder characterized by poor fluency of speech despite the speech production organs being normal. Numerous factors contribute to stuttering, and it may also be an iatrogenic effect of certain drugs. The aim of this study was to investigate the association between stuttering and drug exposure.Research design and methods: We investigated the association between drugs and stuttering. We analyzed reports in the World Health Organization global individual case safety reports database (Vigibase) up to 31 May 2020 with the MedDRA lower level terms 'stutter' and 'stuttering.' The association between a drug and the occurrence of the adverse drug reaction was estimated by disproportionality analysis. Reporting odds ratios (ROR) were calculated with 95% confidence intervals.Results: In total, 724 notifications were identified using the MedDRA terms selected. The main drugs implicated were methylphenidate (ROR = 19.58; 95% CI: 13.3-28.8), topiramate (ROR = 12.5; 95% CI: 7.1-22.1), olanzapine (ROR = 12; 95% CI: 8-17.9) and golimumab (ROR = 10.2; 95% CI: 5.5-19.1).Conclusions: When stuttering occurs in a patient treated by drugs affecting neurotransmission, a drug-induced origin of the stutter should be considered.

Clozapine and speech dysfluency: two case reports

Aims and Method

We describe two patients, both diagnosed with psychotic illnesses, who developed stuttering while being treated with clozapine.

Results

In both patients the stuttering was severe and significantly impaired progress towards recovery. Deviant speech dimensions and voice quality were consistent with dysarthria and dystonia.

Clinical Implications

Patients who develop abnormal electroencephalogram activity and those who have a family or personal history of stuttering might be at increased risk of developing speech problems with clozapine. Speech dysfluency might be a consequence of clozapine's action in lowering the seizure threshold. Potential management strategies include the use of sodium valproate and changing the type of antipsychotic.

Clozapine-Induced Microseizures, Orofacial Dyskinesia, and Speech Dysfluency in an Adolescent with Treatment Resistant Early Onset Schizophrenia on Concurrent Lithium Therapy. Case Rep Psychiatry. 2017;2017:7359095. [PMID: 28835863 PMCID: PMC5556608 DOI: 10.1155/2017/7359095]

Clozapine is an atypical antipsychotic used in the treatment of refractory schizophrenia. It has a well-known side effect profile, including agranulocytosis, decreased seizure threshold, and tardive dyskinesia. In addition, numerous case reports have described clozapine-induced stuttering in adults. However, there has been only one previous case report describing it in the adolescent population. In addition, concurrent lithium therapy has been shown to enhance the neurotoxic effects of antipsychotics and lower the seizure threshold. Here, we report on the development of clozapine-induced microseizures, orofacial dyskinesia, and stuttering in a 17-year-old adolescent male with treatment of refractory early onset schizophrenia on clozapine and concurrent lithium therapy. The patient's symptoms of schizophrenia responded well to the clozapine regimen. However, with the escalating dose of clozapine, the patient developed speech dysfluency in the form of stuttering and perioral twitching. An electroencephalogram confirmed seizure activity. Due to similarities with tardive dyskinesia, symptoms of microseizures induced by atypical antipsychotics may not be accurately diagnosed. A multidisciplinary treatment of speech dysfluency is of particular importance in the adolescent schizophrenic patients, who are expected to have longer duration of lifetime exposure to antipsychotics and in whom peer group interaction is crucial for normal personal and social development.

Clozapine-induced stuttering: an estimate of prevalence in the west of Ireland

OBJECTIVES

Clozapine is the most effective treatment available for treatment-resistant schizophrenia; however, it is also associated with a large array of adverse effects that limits its tolerability. A number of previous case reports have noted an association between clozapine and stuttering, however the rate of this possible adverse effect is yet to be established.

METHODS

In this paper, we present six cases of patients treated with clozapine who developed stuttering.

RESULTS

Clozapine was associated with stuttering in 0.92% of individuals treated with clozapine in the region. Clozapine-induced stuttering was associated with an increase in treatment dose or with dose titration at initiation of clozapine in five individuals, with dose reduction or slower dose titration associated with a cessation of stuttering in these cases.

CONCLUSIONS

This is the largest case series to date examining clozapine-induced stuttering and indicates that clozapine-induced stuttering is a relatively common adverse effect that can be managed by a slower titration of clozapine dosage or a modest reduction in dose in most cases.

Evaluating the effect of risperidone on speech: A cross-sectional study

Speech subsystems are susceptible to the effects of several factors including medications. The atypical antipsychotics can also adversely affect the speech because of its action on serotonin and dopamine neurotransmitters. The present study aims to analyze the speech characteristics associated with atypical antipsychotic risperidone. Speech of 92 patients on risperidone with or without trihexyphenidyl and/or clonazepam were compared with that of 31 persons who were not on any psychotropic medicines. Compared to control group, maximum phonation duration, sequential motion rate of diadochokinesia was reduced by about 3s and 1syllable/s respectively and s/z ratio was increased by 0.16 in patients with risperidone. Performance of larynx, lips and tongue sub-system and intelligibility of speech were also significantly reduced in risperidone group. Risperidone did impact the phonation and articulation sub-systems of speech mildly, which was independent of tardive dyskinesia and extrapyramidal symptoms. Randomized controlled prospective study looking into impact on speech and related effect on drug adherence, functioning and quality of life needs to be conducted with risperidone and other atypical antipsychotics.

Clozapine induced stuttering

We describe two cases reports, demonstrating an association between clozapine treatment and stuttering. Stuttering in both cases was dose-related and a significant improvement was noted when the dose of clozapine was reduced.

Clozapine-induced stuttering: a case report and analysis of similar case reports in the literature

There is limited literature reporting clozapine-associated stuttering. In this case report, we present a case of a young male who developed stuttering with clozapine, which improved with dose reduction. Computer-assisted searches on clozapine-induced stuttering yielded 16 cases, and analysis of these case reports suggests that stuttering may be linked to seizures or movement disorders, but other putative mechanisms may be at work, which need further research.

Clozapine-related EEG changes and seizures: dose and plasma-level relationships

Clozapine is a widely used atypical antipsychotic with a unique effectiveness in treatment-resistant schizophrenia. An important adverse effect is seizures, which have been observed at all stages of clozapine treatment. Valproate has traditionally been considered the drug of choice for the prophylaxis of clozapine seizures, however it may not be the most suitable choice for all patients. There is disagreement as to the best point to prescribe valproate or a suitable antiepileptic: as seizure prophylaxis at a certain clozapine dose or level, or only as remedial treatment. In this review, we examine the relevant literature with an aim to evaluate the following relationships: clozapine dose and electroencephalogram (EEG) abnormalities, plasma levels and EEG abnormalities, dose and occurrence of seizures and plasma levels and occurrence of seizures. Weighted linear regression models were fitted to investigate these relationships. There was a strong relationship between clozapine dose and plasma level and occurrence of clozapine-induced EEG abnormalities. However, a statistically significant relationship between dose and occurrence of seizures was not found. A relationship between clozapine plasma level and occurrence of seizures was not established because of the scarcity of useful data although our review found three case reports which suggested that there is a very substantial risk of seizures with clozapine plasma levels exceeding 1300 μg/l. Seizures are more common during the initiation phase of clozapine treatment, suggesting a slow titration to target plasma levels is desirable. An antiepileptic drug should be considered when the clozapine plasma level exceeds 500 μg/l, if the EEG shows clear epileptiform discharges, if seizures, myoclonic jerks or speech difficulties occur and when there is concurrent use of epileptogenic medication. The antiepileptics of choice for the treatment and prophylaxis of clozapine-induced seizures are valproate (particularly where there is mood disturbance) and lamotrigine (where there is resistance to clozapine).

Risperidone induced stuttering

Stuttering as a side effect of antipsychotics is rare. There are a few case reports of antipsychotic-induced stuttering, namely, chlorpromazine, levomepromazine, trifluoperazine, fluphenazine, olanzapine and clozapine. Risperidone is commonly used as an atypical antipsychotic. It is licensed for both acute and chronic psychosis and mania. There is only one documented case report mentioned on risperidone induced stuttering. One case report of risperidone-induced stuttering is now described. Stuttering is a rare side effect and requires a high index of suspicion for diagnosis. Further study and research to identify the neurophysiological and psychological processes behind adult onset stuttering and identification of the processes involved in risperidone induced stuttering would help our understanding further.

Use of lamotrigine in a patient with a clozapine-related seizure

Seizures can be a serious adverse effect of clozapine, often a last-resort antipsychotic with unique efficacy for some patients. Several anticonvulsants have been reported to be useful in preventing further clozapine-induced seizures and permitting continued treatment with this medication. The authors describe the first reported successful use of lamotrigine for this purpose.

Olanzapine for the treatment of acquired neurogenic stuttering

Stuttering is a vocal phenomenon, which manifests itself as disturbances in speech fluency. While stuttering is most commonly treated with speech therapy and psychotherapy, a number of antipsychotic agents have been investigated as possible treatments. We present the case of a 37-year-old man who developed a post-concussive syndrome with psychosis and associated stuttering after his second exposure to a blast from an improvised explosive device (IED). After treatment with olanzapine, both his psychosis and his stuttering showed significant improvement. We also discuss stuttering and review previous studies that have investigated antipsychotic use in stuttering.

Clozapine-induced seizures: recognition and treatment

OBJECTIVES

To inform clinicians about the types of seizures that can be induced by clozapine and to provide recommendations for treatment.

METHODS

We identified articles on clozapine-induced seizures from a MEDLINE search of the English-language literature from 1978 to July 2006. The frequency of each type of seizure and the dosages of clozapine associated with seizures were compiled. In addition to this review, we report a new case illustrating the challenge of diagnosing subtle seizure activity.

RESULTS

The tonic-clonic variety is the most frequently described clozapine-induced seizure. Myoclonic and atonic seizures together constitute about one-quarter of the reported seizures. The mean dosage of clozapine associated with seizures is not high (less than 600 mg daily).

CONCLUSIONS

It may be difficult for clinicians to recognize subtle types of clozapine-induced seizures, such as myoclonic, atonic, or partial seizures. Clinicians should not place excessive reliance on the plasma level of clozapine or electroencephalogram findings to predict the occurrence of seizures. When a first seizure occurs, it is recommended that the dosage of clozapine be reduced or an alternative antipsychotic agent be employed. If a second seizure occurs, an anticonvulsant drug should be started. Special attention should be paid when commencing or discontinuing concurrent medication that may affect the plasma level of clozapine.