Stuttering: an unusual side effect of phenothiazines

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 In 55.8% of the episodes of DIS, the offending drug was withdrawn to manage stuttering, which resulted in significant improvement or complete relief of stuttering in all cases.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.

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.

Phenothiazine antipsychotics exhibit dual properties in pseudo-allergic reactions: Activating MRGPRX2 and inhibiting the H1 receptor

Phenothiazines are a class of antipsychotics that share the same tricyclic structure and are widely used in clinical settings. Adverse reactions from these drugs, however, have been regularly reported, with allergic skin reactions noted in some cases. Nevertheless, the mechanisms underlying anaphylaxis by these drugs have not been described. In the present study, we found that phenothiazine antipsychotics increased calcium mobilization and activated mast cells to release β-hexosaminidase, histamine, and tumor necrosis factor-α via Mas-related G-protein-coupled receptor member X2 (MRGPRX2) in vitro. In addition, they induced histamine release in serum via Mrgprb2 in C57BL/6 mice without Evans blue extravasation or paw swell. Further experiments indicated these drugs had good interaction with the histamine H₁ receptor (H1R) and show an anti-calcium mobilization effect on H₁R-HEK293 cells, which confirmed a potential antagonist effect of these drugs on the H₁R. The molecular docking and activity experiments indicated that the N-methyl substitution on the side chain of these drugs played a significant role in activating MRGPRX2, while the phenothiazine tricyclic ring was associated with the inhibiting effect on the H₁R. Therefore, due to their dual properties of increasing histamine levels without obvious allergic symptoms, clinicians should be highly vigilant for damage from histamine accumulation and long-term inflammatory reactions during the clinical use of phenothiazine antipsychotics.

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 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.

A Case of Risperidone Induced Stuttering as a Paradox

The main feature of stuttering is the disturbance in terms of both timing and fluency of speech inappropriate with the age. This disturbance is characterized with the repetition and prolongation of sounds and syllables. There are two types of stuttering as acquired and developmental. Acquired stuttering may begin suddenly at any age and may be seen rarely due to the adverse effects of drugs. Stuttering induced by antipsychotics may develop very rarely. Risperidone is a strong antagonist of dopamin 2 (D₂) and serotonin 2A (5 HT_2A) and shows a high affinity for α₁ and α₂ noradrenaline receptors. It's used in a wide spectrum including psychotic disorders, mood disorders, and behavioral disorders, even for the treatment of stuttering. Risperidone treats the symptoms of stuttering by the antagonism of D₂ receptors with an increase in striatal metabolism. In literature, we haven't observed any other case reports except the two stuttering cases with psychotic disorders due to the short term and high-dose risperidone treatment. In our case, stuttering adverse effect of chronic low-dose risperidone treatment is remarkable that is discussed for the first time. As well as the use of risperidone for the treatment of stuttering, stuttering adverse effect seems to be interesting as a paradox.

A case of bupropion-induced stuttering

OBJECTIVE

Stuttering is a frequent side effect of many psychotropic drugs, particularly antidepressants.

METHOD

This is a case report of a woman presenting with stuttering after starting bupropion treatment for her depression.

RESULTS

The patient's stuttering resolved after discontinuing the bupropion.

CONCLUSION

Neuroimaging and pharmacological studies have implicated dopamine in the pathophysiology of stuttering. Bupropion's ability to increase dopamine in the frontal cortex was suspected to have been involved in this patient's stuttering. However, further research is needed before causality can be assured.

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.

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.

Drug-induced stuttering: a review of the literature

The author critically reviews the world literature on drug-induced stuttering. The literature on stuttering as a side effect of pharmacologic agents was identified by means of a computer-assisted search. A diversity of drugs has been reported to induce stuttering in susceptible persons, including some agents that improve the speech of some known stutterers. In all instances, normal speech returned shortly after the offending drug was discontinued. Multiple, interacting neurotransmitter systems seem to be involved. Drug-induced imbalances in these systems may account for the speech disturbances.

Stuttering may be a type of action dystonia

We observed abnormal involuntary movements, involving principally the facial and neck muscles, in 23 patients with stuttering. These movements were similar to involuntary movements seen in distinct dystonic syndromes. There was a history of stuttering in the first degree relatives of six patients. The association of stuttering with degenerative neurologic disorders and focal brain lesions, cerebral blood flow changes in patients with developmental stuttering, its occurrence as a side effect of centrally acting drugs, induction and alleviation of stuttering by mechanical perturbation, or by electrical stimulation of the thalamus, a strong genetic predisposition with male preponderance, and the statistically significant occurrence of stuttering in the family history of patients with idiopathic torsion dystonia suggest an organic basis for developmental stuttering. These findings and the reported similarities between the involuntary movements associated with stuttering and dystonic involuntary movements support the hypothesis that stuttering is a form of segmental or focal action dystonia.

Stuttering as a phenotype for behavioral genetics research

Stuttering is a broad behavioral phenotype with an adult prevalence of 0.7-1.0%. Family, twin, and segregation studies all indicate that stuttering has a large genetic component to its etiology. The relatively simple phenotype, the early onset, and the apparent rarity of phenocopies of adult stuttering all make stuttering a promising model for the study of the genetics of broad behavioral phenotypes.

Spastic dysphonia and denervation signs in a young man with tardive dyskinesia

Pathophysiological theories of tardive dyskinesia (TD) suggest the possibility of structural changes in the central nervous system of patients with TD. This report describes a case of choreoathetoid dyskinesia and spastic dysphonia associated with clinical and electromyographic signs of muscle denervation. The findings of this case suggest that the neurological syndrome originates within basal ganglia nuclei but may also extend to the peripheral neuromuscular system.