Drug-induced myoclonus: frequency, mechanisms and management

Drug-Induced Myoclonus: A Systematic Review

Background and Objectives: Myoclonus is already associated with a wide variety of drugs and systemic conditions. As new components are discovered, more drugs are suspected of causing this disabling abnormal involuntary movement. This systematic review aims to assess the medications associated with drug-induced myoclonus (DIM). Materials and Methods: Two reviewers assessed the PubMed database using the search term "myoclonus", without language restriction, for articles published between 1955 and 2024. The medications found were divided into classes and sub-classes, and the subclasses were graded according to their level of evidence. Results: From 12,097 results, 1115 were found to be DIM. The subclasses of medications with level A evidence were intravenous anesthetics (etomidate), cephalosporins (ceftazidime, cefepime), fluoroquinolones (ciprofloxacin), selective serotonin reuptake inhibitors (citalopram, escitalopram, paroxetine, sertraline), tricyclic antidepressant (amitriptyline), glutamate antagonist (amantadine), atypical antipsychotics (clozapine, quetiapine), antiseizure medications (carbamazepine, oxcarbazepine, phenytoin, gabapentin, pregabalin, valproate), pure opioid agonist (fentanyl, morphine), bismuth salts, and mood stabilizers (lithium). The single medication with the highest number of reports was etomidate. Drug-induced asterixis is associated with a specific list of medications. The neurotransmitters likely involved in DIM are serotonin, dopamine, gamma-aminobutyric acid (GABA), and glutamate. Conclusions: DIM may be reversible with management that can include drug discontinuation, dose adjustment, and the prescription of a medication used to treat idiopathic myoclonus. Based on the main clinical constellation of symptoms and pathophysiological mechanisms found in this study, DIM can be categorized into three types: type 1 (serotonin syndrome), type 2 (non-serotonin syndrome), and type 3 (unknown).

Dobutamine induced multifocal myoclonus in a patient with chronic kidney disease

Adverse drug reactions (ADRs) are common in clinical practice, especially among patients with multiple comorbidities and polypharmacy. The ADRs associated with medications may be minor or life-threatening. Many available ADR assessment scales and pharmacovigilance programmes have streamlined the early diagnosis and management of ADRs. Dobutamine is a commonly used inotropic agent in patients with cardiovascular decompensation which is caused by depressed contractility secondary to organic heart disease, cardiac surgery, cardiac arrest or acute myocardial infarction. Dobutamine-associated adverse effects are mainly due to sympathetic overstimulation causing chest discomfort, palpitations, tremors, headache, shortness of breath, hypertension, nausea, vomiting and eosinophilic myocarditis. Myoclonus is a neurological side effect that may be rarely caused by dobutamine infusion, especially among patients with chronic kidney disease (CKD). We are reporting a rare case of dobutamine-induced multifocal myoclonus in a patient with CKD during the management of decompensated heart failure.

Propofol-Induced Fasciculations in a Patient With Obstructive Sleep Apnea: A Case Report

We report a case of a 39-year-old male patient who developed propofol-induced fasciculations during the induction of general anesthesia. The patient had a history of moderate obstructive sleep apnea and was intolerant to continuous positive airway pressure therapy. He subsequently underwent the insertion of a hypoglossal nerve stimulator as a viable surgical intervention. The patient had a drug-induced sleep endoscopy that showed a 100% obstruction at the velum and the oropharynx, mainly in the anteroposterior and lateral directions. The patient experienced a smooth induction and emergence from general anesthesia, except for a brief episode of myoclonus-like movement in the bilateral upper extremities after propofol administration. The patient recovered well and reported an improvement in his sleep quality and daytime symptoms.

Dextromethorphan Induced Dystonia: A Rare Case Report

Dextromethorphan is a distant derivative of morphine, used as an antitussive agent indicated in standard care for various infections and respiratory conditions ranging from the common cold (rhinoviruses) to severe acute respiratory illness (SARI). Being a derivative of morphine, a natural central nervous system (CNS) depressant, dextromethorphan produces little to no action on CNS when ingested in the prescription dosage. We present a case of a 64-year-old female patient, a known case of ischemic heart disease post angioplasty and stenting to the left anterior descending artery (LAD), with heart failure with reduced ejection fraction (HFrEF), diabetes, hypertension, chronic kidney disease, and hypothyroidism who developed extrapyramidal symptoms post dextromethorphan administration. The incidence of dextromethorphan-induced dystonia is unknown, and the literature review suggests 4 case reports indicating dextromethorphan-induced dystonia, and each of those reports is a case of either accidental overdose or overdose in substance abuse disorder. No cases of these CNS side effects are described among adults with a therapeutic dose of dextromethorphan. This case report serves to sensitize the clinician about this rare occurrence.

Myoclonus Secondary to Amantadine: Case Report and Literature Review

The usual adverse events of amantadine are dizziness, dry mouth, and peripheral edema. Postmarketing experience has revealed abnormal movements such as tremors, involuntary muscle contractions, and gait abnormalities. Herein, we report a case of an elderly male who presented with generalized twitching associated with amantadine. A 64-year-old male presenting with jerking movements within one day of onset was admitted. Sudden and involuntary distal lower and upper limb muscle twitching was observed. The subject presented subsequent brief movements when attempting to stand or hold arms antigravity. He was diagnosed with Parkinson's disease three years ago. Eight days before the presentation to the emergency department, he consulted with his primary care physician, who prescribed amantadine to improve his motor symptoms. On the seventh day, he developed brisk abnormal movements. Laboratory exams, neuroimaging, and electroencephalogram were unremarkable. Amantadine was discontinued. After three days, the patient reported that his jerking movements had fully recovered. To the authors' knowledge, 22 individuals with amantadine-associated myoclonus had already been reported in the literature. The pathophysiology of amantadine-induced myoclonus is probably related to serotoninergic pathways. Myoclonus secondary to amantadine was slightly more common in men. The population affected was elderly, with a mean and median age of 67.7 and 64 years.

Dobutamine-Induced Myoclonus in a Peritoneal Dialysis Patient: Case Report

Dobutamine is a weak beta-1 and a potent beta-2 adrenergic agonist commonly used to treat patients in cardiogenic shock. It enhances myocardial contractibility, increasing cardiac output. Myoclonus in patients receiving an infusion of dobutamine is rare and, although not fully understood, seems more common in patients with severe kidney failure. To our knowledge, this is the first reported case of dobutamine-induced myoclonus in a patient with kidney failure receiving peritoneal dialysis. Only 7% of the 518,749 patients of the United States requiring kidney replacement therapy receive peritoneal dialysis, with only a small unknown number of those with advanced heart failure manage with an infusion of inotropic medication. The low prevalence of combined advanced heart failure and kidney failure could partly explain this condition's rarity. In this study, we report the case of a 64-year-old woman with kidney failure receiving peritoneal dialysis in whom myoclonus developed 3 weeks after starting a dobutamine infusion for advanced refractory heart failure. Infectious and other pharmacologic causes of myoclonus were ruled out. Initially, uremia was suspected; however, despite increasing her peritoneal dialysis dose, it was only after discontinuing the dobutamine infusion that her myoclonus resolved.

Hemicrania continua: Indomethacin induced myoclonus

Myoclonus has been described rarely as an adverse effect with some non-steroidal anti-inflammatory drugs, but never with indomethacin. Indomethacin is a common nonsteroidal anti-inflammatory drug used for various primary headache disorders, including hemicrania continua. We present a rare case of a 45-year-old male with hemicrania continua who developed myoclonus from indomethacin. These movements resolved completely following discontinuation of indomethacin. The disturbance on the serotonergic and GABAergic systems may be associated with indomethacin induced myoclonus. Clinicians and patients should be mindful with this potential side effect with indomethacin.

Amantadine Associated Myoclonus: Case Report and Review of the Literature

PURPOSE

Amantadine is commonly used to treat Parkinson's disease. A case of myoclonus and asterixis was associated with amantadine is reported.

CASE SUMMARY

An 80-year-old man with Parkinson's disease diagnosed in 2015 was started on amantadine for treatment of progressive tremor and orofacial dyskinesias induced by levodopa. He took amantadine 100mg orally daily for 7 days, then increased to 100mg twice a day thereafter. The patient complained of "worsening tremor" after 9 days and amantadine was decreased to 100mg daily. After 1 month on this dose, the patient reported that his "tremor" persisted and experienced visual hallucinations. His examination demonstrated diffuse myoclonus throughout his extremities and trunk, as well as asterixis when attempting to stand or holding his arms antigravity. Laboratory testing for renal and hepatic failure was unrevealing. Amantadine was reduced to 50mg daily for 4 days and then discontinued. Myoclonus resolved 3 days after discontinuation of amantadine.

CONCLUSION

While amantadine-induced myoclonus is rare, health care providers should be vigilant in monitoring for signs and symptoms of myoclonus following amantadine initiation.

Assessment of Extrapyramidal Symptoms Associated with Psychotropics Pharmacological Treatments, and Associated Risk Factors

BACKGROUND

Extrapyramidal Symptoms (EPS) are unwanted symptoms commonly originating from the use of certain medications. The symptoms can range from minimal discomfort to permanent involuntary muscular movements. The aims of the study were to examine the incidence of drug-induced extrapyramidal symptoms (di-EPS), associated risk factors, and clinical characteristics.

METHODS

This is a retrospective, observational study of di-EPS conducted in outpatient clinics of Jordan using the longitudinal health database (Hakeem®) for data collection. Patients who received drugs with the risk of EPS during the period 2010-2020 were included and followed. Patients with any of the known underlying conditions that may cause EPS or were currently taking drugs that may mask the symptoms were excluded. Gender and age-matched control subjects were included in the study. The Statistical Package for Social Science (SPSS®) version 26 was used for data analysis.

RESULTS

The final dataset included 34898 exposed patients and 69796 matched controls. The incidence of di-EPS ranged from 9.8% [Amitriptyline 25mg] to 28.9% (Imipramine 25mg). Baseline factors associated with a significantly higher risk of developing di-EPS were age {HR: 1.1 [95%CI: 0.8-1.2, p=0.003], smoking {HR: 1.7 (95%CI: 1.3-2.2), p=0.02}, tremor history {HR: 7.4 (95%CI: 5.9-8.3), p=.002} and history of taking antipsychotics {HR: 3.9, (95% CI: 2.5-4.6), p=0.001}. Patients taking paroxetine {HR: 8.6 [95%CI: 7.4-9.8], p=.0002},imipramine {HR: 8.3, [7.1-10.5], p=0.01}, or fluoxetine {HR: 8.2 (95%CI: 6.8-9.3), p=.006} had a significantly higher risk of developing di-EPS compared to patients taking citalopram. Myoclonus, blepharospasm, symptoms of the basal ganglia dysfunction, and organic writers' cramp were reported among participants.

CONCLUSION

Patients treated with paroxetine, imipramine, fluoxetine, or clomipramine had a higher risk of developing di-EPS than patients treated with citalopram. The difference in gender was not significantly related to di-EPS development. Whereas age, smoking, and history of taking antipsychotics were significantly associated with di-EPS development.

KEY FINDINGS

• High incidence of drug-induced extrapyramidal symptoms (di-EPS) was reported• Age, smoking, tremor history, and history of taking antipsychotics were risk factors of drug-induced extrapyramidal symptoms.• Patients taking paroxetine, imipramine or fluoxetine had a significantly higher risk of developing di-EPS compared to patients taking citalopram.

Tardive syndrome: An update and mini-review from the perspective of phenomenology

Tardive syndrome (TS) is a group of movement disorders caused by the long-term use of dopamine receptor blocking agents. The phenotypic presentation of TS is diverse, ranging from the most well-characterized symptom of tardive dyskinesia to other symptoms, including dystonia, akathisia, myoclonus, parkinsonism, tremor, and tics. These tardive symptoms are distinct not only in their phenomenology but also in their clinical outcomes. However, our knowledge of the pathophysiology and management of TS is almost exclusively based on tardive dyskinesia. First-generation antipsychotics have a higher risk of inducing TS and have largely been replaced by second-generation antipsychotics with a lower risk of TS. However, patients with off-label use of second-generation antipsychotics are still at risk of developing TS. Thus, the management of TS remains a challenging and important issue for physicians. In this review, we update the information on the epidemiology, phenomenology, and treatment of TS from the perspective of the specific form of TS.

Cinnarizine- and flunarizine-associated movement disorder: a literature review

Introduction

Cinnarizine (CNZ) and flunarizine (FNZ) belong to the calcium channel blockers class of medication.

Main text

The aim of this literature review is to evaluate the clinical epidemiological profile, pathological mechanisms, and management of CNZ/FNZ-associated movement disorder (MD). Relevant reports in six databases were identified and assessed by two reviewers without language restriction. One hundred and seventeen reports containing 1920 individuals who developed a CNZ/FNZ-associated MD were identified. The MD encountered were 1251 parkinsonism, 23 dyskinesias, 11 akathisia, 16 dystonia, and 5 myoclonus, and in the group not clearly defined, 592 extrapyramidal symptoms, 19 tremors, 2 bradykinesia, and 1 myokymia. The predominant sex was female with a percentage of 72.69% (466/641). The mean age was 74.49 (SD, 7.88) years. The mean CNZ dose was 148.19 mg (SD, 42.51) and for the FNZ dose, 11.22 mg (5.39). The mean MD onset and recovery were 1.83 years (SD, 1.35) and 3.71 months (SD, 1.26). In the subgroup of subjects that had improvement of the symptoms, the complete recovery was achieved within 6 months of the drug withdrawal in almost all subjects (99%). The most common management was drug withdrawal. A complete recovery was observed in 93.77% of the patients (437/466).

Conclusions

CNZ/FNZ-associated MD was extensively reported in the literature. Parkinsonism was the most well described. Myoclonus (MCL) was the poorest described MD with missing data about the neurological examination and electrodiagnostic studies. The knowledge of this disorder probably can contribute to the understanding of the other drug-induced MDs.

Antidepressants and movement disorders: a postmarketing study in the world pharmacovigilance database

BACKGROUND

Antidepressants-induced movement disorders are rare and imperfectly known adverse drug reactions. The risk may differ between different antidepressants and antidepressants' classes. The objective of this study was to assess the putative association of each antidepressant and antidepressants' classes with movement disorders.

METHODS

Using VigiBase®, the WHO Pharmacovigilance database, disproportionality of movement disorders' reporting was assessed among adverse drug reactions related to any antidepressant, from January 1967 to February 2017, through a case/non-case design. The association between nine subtypes of movement disorders (akathisia, bruxism, dystonia, myoclonus, parkinsonism, restless legs syndrome, tardive dyskinesia, tics, tremor) and antidepressants was estimated through the calculation first of crude Reporting Odds Ratio (ROR), then adjusted ROR on four potential confounding factors: age, sex, drugs described as able to induce movement disorders, and drugs used to treat movement disorders.

RESULTS

Out of the 14,270,446 reports included in VigiBase®, 1,027,405 (7.2%) contained at least one antidepressant, among whom 29,253 (2.8%) reported movement disorders. The female/male sex ratio was 2.15 and the mean age 50.9 ± 18.0 years. We found a significant increased ROR for antidepressants in general for all subtypes of movement disorders, with the highest association with bruxism (ROR 10.37, 95% CI 9.62-11.17) and the lowest with tics (ROR 1.49, 95% CI 1.38-1.60). When comparing each of the classes of antidepressants with the others, a significant association was observed for all subtypes of movement disorders except restless legs syndrome with serotonin reuptake inhibitors (SRIs) only. Among antidepressants, mirtazapine, vortioxetine, amoxapine, phenelzine, tryptophan and fluvoxamine were associated with the highest level to movement disorders and citalopram, paroxetine, duloxetine and mirtazapine were the most frequently associated with movement disorders. An association was also found with eight other antidepressants.

CONCLUSIONS

A potential harmful association was found between movement disorders and use of the antidepressants mirtazapine, vortioxetine, amoxapine, phenelzine, tryptophan, fluvoxamine, citalopram, paroxetine, duloxetine, bupropion, clomipramine, escitalopram, fluoxetine, mianserin, sertraline, venlafaxine and vilazodone. Clinicians should beware of these adverse effects and monitor early warning signs carefully. However, this observational study must be interpreted as an exploratory analysis, and these results should be refined by future epidemiological studies.

The Link Between Amitriptyline and Movement Disorders: Clinical Profile and Outcome

INTRODUCTION

Amitriptyline (AMT) is a tricyclic antidepressant. In this review, we evaluate the clinical and epidemiological profile, pathological mechanisms and management of AMT-associated movement disorders.

MATERIALS AND METHODS

A search for relevant reports in 6 databases was performed. Studies that reported patients developed only ataxia or tremor after AMT use were excluded.

RESULTS

A total of 48 reports on 200 cases were found. AMT-associated movement disorders included myoclonus (n = 26), dyskinesia (n = 11), dystonia (n = 8), stutter (n = 5), akathisia (n = 3) and restless legs syndrome (n = 1). For less well-defined cases, 99 patients had dyskinesia, 19 had psychomotor disturbances, 3 had myoclonus, 11 had dystonia, 12 had Parkinsonism and 1 each had akathisia and extrapyramidal symptoms. Mean and standard deviation (SD) and median ages were 45.40 years (SD 16.78) and 40 years (range 3.7-82 years), respectively. Over half were women (58.13%) and the most common indication was depression. Mean and median AMT doses were 126 mg (SD 128.76) and 75 mg (range 15-800 mg), respectively. In 68% of patients, onset of movement disorders was <1 month; time from AMT withdrawal to complete recovery was <1 month in 70% of cases. A weak negative linear correlation (r = -0.0904) was found between onset of movement disorders and AMT dose. AMT withdrawal was the most common treatment.

CONCLUSION

Amitriptyline is associated with various movement disorders, particularly myoclonus, dystonia and dyskinesias. Stutters and restless legs syndrome are some of the less common associations.

Tremor and myoclonus

Tremor and myoclonus are two common hyperkinetic movement disorders. Tremor is characterized by rhythmic oscillatory movements while myoclonic jerks are usually arrhythmic. Tremor can be classified into subtypes including the most common types: essential, enhanced physiological, and parkinsonian tremor. Myoclonus classification is based on its anatomic origin: cortical, subcortical, spinal, and peripheral myoclonus. The clinical presentations are unfortunately not always classic and electrophysiologic investigations can be helpful in making a phenotypic diagnosis. Video-polymyography is the main technique to (sub)classify the involuntary movements. In myoclonus, advanced electrophysiologic testing, such as back-averaging, coherence analysis, somatosensory-evoked potentials, and the C-reflex can be of additional value. Recent developments in tremor point toward a role for intermuscular coherence analysis to differentiate between tremor subtypes. Classification of the movement disorder based on clinical and electrophysiologic features is important, as it enables the search for an etiological diagnosis and guides tailored treatment.

Buspirone-associated Movement Disorder: A Literature Review

Buspirone (BUS) belongs to the azapirone chemical class. The aim of this literature review is to evaluate the clinical epidemiological profile, pathological mechanisms, and management of BUS-associated movement disorders (MD). Relevant reports in six databases were identified and assessed by two reviewers without language restriction. A total of 25 reports containing 65 cases were assessed. The MD associated with BUS were: dyskinesia in 14 cases, 10 of akathisia, 8 of myoclonus, 6 of Parkinsonism, and 6 of dystonia. The cases not clearly defined were 7 tension, 14 incoordination, and the undefined number of dyskinesia, tics, and Parkinsonism. The mean age was 45.23 years (range: 15-74). The male was the predominant sex in 60.86% and the most common BUS-indication was anxiety disorder. The mean BUS-dose was 42.16 mg (range: 5-100). The time from the beginning of BUS administration to the MD onset was one month or less in 76%. The time from BUS withdrawal to complete recovery was within one month in 87.5%. The most common management was BUS withdrawal. In 16 patients the follow-up was reported: 14 had a full recovery, but in two (1 dyskinesia + 1 dystonia) the symptoms continued after the BUS withdrawal. MD associated with BUS were scarcely reported in the literature. Moreover, in the majority of cases, no clear description of the clinical profile, neurological examination, or the time data of the movement disorder onset and recovery were given.

Carbamazepine-, Oxcarbazepine-, Eslicarbazepine-Associated Movement Disorder: A Literature Review

BACKGROUND

Carbamazepine (CBZ), oxcarbazepine (OXC), and eslicarbazepine (ESL) acetate belong to the dibenzazepine family. In this context, the aim of this literature review is to evaluate the clinical epidemiological profile, pathological mechanisms, and management of CBZ-, OXC-, and ESL-associated movement disorders (MDs).

REVIEW SUMMARY

Relevant reports in 6 databases were identified and assessed by 2 reviewers without language restriction. Reports where the individuals only developed tremor or ataxia after CBZ/OXC/ESL use were not included. A total of 73 reports containing 191 individuals who developed MD associated with CBZ/OXC/ESL were identified. Were found, respectively, the following: 33 patients with myoclonus, 23 with dystonia, 14 with tics, 13 with dyskinesia, 8 with parkinsonism, and 5 with akathisia. In the group not clearly defined, there were 44 with myoclonus, 29 with dyskinesia, 20 with dystonia, 1 with incoordination, and 1 with akathisia. The mean age was 28.53 years. The most frequent sex was male in 52.77% (38/72), and the drug indication was epilepsy in 74.19% (69/93). The mean (SD) CBZ dose when the MD occurred was 692.68 (363.58) mg. The mean time until MD onset was 33.59 days, and the mean recovery period was 8.7 days. The most common form of MD management was drug withdrawal.

CONCLUSIONS

The number of cases associated with CBZ is higher than those with OXC + ESL. We believe that the study of CBZ contributes not only to the improvement of this drug but also to the knowledge about the drug-induced MD of OXC and ESL. In the literature, the description of the MD onset and recovery has been poorly reported.

Knee Buckling (Negative Myoclonus) Associated With Clozapine: Reports on 3 Cases

BACKGROUND

Negative myoclonus is rarely seen in the clinical setting. It can be involved in some central nervous system pathologies. It has also been observed after antipsychotic treatment.

CASE REPORTS

In this article, we will present 3 cases diagnosed with negative myoclonus in a 120-bed university-affiliated hospital within the past 7 years. Based on our clinical experience, it was observed that myoclonic jerk was a rare condition that started with suddenly dose changes. Patients showed good improvement in response to dose reduction.

CONCLUSIONS

Since the number of reported cases on negative myoclonus is limited, there is still a lack of well-established consensus on the management of this disease. It can be concluded that myoclonic jerk may be dose-dependent, sudden dose changes may be effective, anticonvulsants are not effective in all cases, and treatment can be achieved by reducing the dose.

Mioclonías inducidas por salbutamol

El salbutamol es un agonista adrenérgico β2 ampliamente empleado en pacientes con enfermedades pulmonares obstructivas y restrictivas. Sus principales efectos secundarios son la taquicardia y el temblor. Las mioclonías son contracciones musculares involuntarias, irregulares, bruscas, breves y repentinas, y pueden ser generalizadas, focales o multifocales.Se presenta el caso de un paciente de 61 años con mioclonías de difícil manejo que solo presentó mejoría tras la suspensión definitiva del agonista adrenérgico β2. Se describen los hallazgos clínicos, las intervenciones y el resultado en las mioclonías asociadas con el uso de salbutamol y se discuten la posible génesis y la importancia de este efecto adverso. Para documentar el caso, se siguieron las recomendaciones de las guías para el reporte de casos (CAse REport, CARE).Aunque en diversos estudios se han descrito mioclonías secundarias al uso de diferentes fármacos, hasta donde se sabe, este sería el cuarto reporte de un caso asociado específicamente con el uso del salbutamol.

Pediatric Iatrogenic Movement Disorders

The acute development of a movement disorder is often a dramatic and frightening experience for patients and families, often requiring urgent or emergent evaluation by a neurologist. In the assessment of these patients, one relies on the history, physical and neurologic examination to determine the etiology of the condition. We aim to demonstrate that a thorough medication history is an incredibly critical part of this evaluation as iatrogenic movement disorders can arise from exposure not only to psychoactive medications, but from drugs prescribed for a variety of nonneurologic disorders. This comprehensive review is organized by movement disorder semiology so that the reader can more readily develop a differential diagnosis when evaluating a patient with a movement disorder.

Myoclonic Disorders

Few movement disorders seem to make a straightforward approach to diagnosis and treatment more difficult and frustrating than myoclonus, due to its plethora of causes and its variable classifications. Nevertheless, in recent years, exciting advances have been made in the elucidation of the pathophysiology and genetic basis of many disorders presenting with myoclonus. Here, we provide a review of all of the important types of myoclonus encountered in pediatric and adult neurology, with an emphasis on the recent developments that have led to a deeper understanding of this intriguing phenomenon. An up-to-date list of the genetic basis of all major myoclonic disorders is presented. Randomized studies are scarce in myoclonus therapy, but helpful pragmatic approaches at diagnosis as well as treatment have been recently suggested.

Contrast induced spinal myoclonus after percutaneous coronary intervention

We present a case of a 77-year-old man diagnosed with contrast-induced spinal myoclonus following primary percutaneous coronary intervention. After being admitted with a diagnosis of anteroseptal myocardial infarction, he underwent primary percutaneous coronary intervention to the left anterior descending artery and was prescribed aspirin, clopidogrel, and intravenous heparin. The following day he developed non-intentional irregular jerky movements confined to the truncal area. In view of rhythmic jerking confined to muscles innervated by a restricted segment of the spinal cord, resistance to supra-spinal influences and voluntary action, and no preceding electroencephalography activity in the contralateral sensorimotor cortex, a diagnosis of spinal myoclonus was made. Spinal myoclonus is a rare entity in which myoclonic movements occur in muscles originating from few (segmental), or many adjacent spinal motor roots (propriospinal). Structural lesions are found in the majority of cases but the actual pathophysiology is still unknown. Contrast-induced spinal myoclonus is an even rarer phenomenon with few published reports. We describe postulated mechanisms and the management of this phenomenon. <Learning objective: Myoclonus is a jerky movement due to abrupt involuntary contractions involving agonist and antagonist muscles. Spinal myoclonus is a rare disorder where myoclonic movements occur in muscles originating from spinal motor roots. The cause is usually a structural lesion, but in rare cases it can be induced by contrast. A video of this rare phenomenon is available with this article and the proposed pathophysiological mechanisms and treatment are discussed.>.

A Rare Instance of Levofloxacin Induced Myoclonus

Levofloxacin is a widely used fluoroquinolone, mainly as a respiratory antimicrobial agent. It is employed as a second line therapeutic modality in pulmonary tuberculosis as well. The drug has been in use for ages, and is known to be both efficacious and safe. However, it is not free of adverse effects. The most dangerous ones are those involving the Central Nervous System (CNS). Although rare, levofloxacin can cause involuntary movements like chorea and myoclonus. Here by, we present a case of an elderly male patient who developed reversible myoclonus/chorea after a course of levofloxacin (which was initiated as part of his anti-tubercular therapy) following the development of peripheral neuropathy secondary to isoniazid.

The clinical heterogeneity of drug-induced myoclonus: an illustrated review

A wide variety of drugs can cause myoclonus. To illustrate this, we first discuss two personally observed cases, one presenting with generalized, but facial-predominant, myoclonus that was induced by amantadine; and the other presenting with propriospinal myoclonus triggered by an antibiotic. We then review the literature on drugs that may cause myoclonus, extracting the corresponding clinical phenotype and suggested underlying pathophysiology. The most frequently reported classes of drugs causing myoclonus include opiates, antidepressants, antipsychotics, and antibiotics. The distribution of myoclonus ranges from focal to generalized, even amongst patients using the same drug, which suggests various neuro-anatomical generators. Possible underlying pathophysiological alterations involve serotonin, dopamine, GABA, and glutamate-related processes at various levels of the neuraxis. The high number of cases of drug-induced myoclonus, together with their reported heterogeneous clinical characteristics, underscores the importance of considering drugs as a possible cause of myoclonus, regardless of its clinical characteristics.

Myoclonus: Pathophysiology and Treatment Options

OPINION STATEMENT

Treatment of myoclonus requires an understanding of the physiopathology of the condition. The first step in treatment is to determine if there is an epileptic component to the myoclonus and treat accordingly. Secondly, a review of medications (e.g., opiates) and comorbidities (e.g., hepatic or renal failure) is required to establish the possibility of iatrogenic and reversible conditions. Once those are eliminated, delineation between cortical, cortico-subcortical, subcortical, brainstem, and spinal generators can determine the first-line treatment. Cortical myoclonus can be treated with levetiracetam, valproic acid, and clonazepam as first-line agents. Phenytoin and carbamazepine may paradoxically worsen myoclonus. Subcortical and brainstem myoclonus can be treated with clonazepam as a first-line agent, but levetiracetam and valproic acid can be tried as well. L-5-Hydroxytryptophan and sodium oxybate are agents used for refractory cases. Spinal myoclonus does not respond to anti-epileptic drugs, and clonazepam is a first-line agent. Botulinum toxin treatment can be useful for focal cases of spinal myoclonus. The etiology of propriospinal myoclonus is controversial, and a functional etiology is suspected in most cases. Treatment can include clonazepam, levetiracetam, baclofen, valproate, carbamazepine, and zonisamide. Functional myoclonus requires multimodal and multidisciplinary treatment that may include psychotropic drugs and physical and occupational therapy. Close collaboration between neurologists and psychiatrists is required for effective treatment. Finally, deep brain stimulation targeting the globus pallidus pars-interna bilaterally has been used in myoclonus-dystonia when pharmacological treatments have been exhausted.

Clozapine-induced myoclonus: a case report and review of the literature

We describe the case of a young man with treatment-resistant schizophrenia, who developed myoclonus during clozapine titration. This subsequently led to a full tonic-clonic seizure. Clozapine treatment can result in a range of seizure-like activity, the most well-known being tonic-clonic seizures. This case highlights the importance of recognizing and treating clozapine-induced myoclonus, as it can herald the onset of a full seizure, even at low serum clozapine levels. We highlight the variety of ways myoclonus can present clinically and suggest treatment options.

A novel diagnostic approach to patients with myoclonus

Myoclonus is a hyperkinetic movement disorder characterized by brief, involuntary muscular jerks. Recognition of myoclonus and determination of the underlying aetiology remains challenging given that both acquired and genetically determined disorders have varied manifestations. The diagnostic work-up in myoclonus is often time-consuming and costly, and a definitive diagnosis is reached in only a minority of patients. On the basis of a systematic literature review up to June 2015, we propose a novel diagnostic eight-step algorithm to help clinicians accurately, efficiently and cost-effectively diagnose myoclonus. The large number of genes implicated in myoclonus and the wide clinical variation of these genetic disorders emphasize the need for novel diagnostic techniques. Therefore, and for the first time, we incorporate next-generation sequencing (NGS) in a diagnostic algorithm for myoclonus. The initial step of the algorithm is to confirm whether the movement disorder phenotype is consistent with, myoclonus, and to define its anatomical subtype. The next steps are aimed at identification of both treatable acquired causes and those genetic causes of myoclonus that require a diagnostic approach other than NGS. Finally, other genetic diseases that could cause myoclonus can be investigated simultaneously by NGS techniques. To facilitate NGS diagnostics, we provide a comprehensive list of genes associated with myoclonus.

Donepezil-Induced Myoclonus in a Patient With Alzheimer Disease

Objective: To report an uncommon adverse event in an elderly patient related to the cholinesterase inhibitor, donepezil. Case Summary: An 80-year-old Greek woman with Alzheimer disease was admitted to the hospital with a sudden onset of myoclonus in both upper and lower extremities after receiving 30 mg of donepezil daily for 25 days. After 36 hours of donepezil remission, the frequency of the myoclonic jerks was sharply reduced. The patient remains asymptomatic after 6 months of follow-up. Discussion: Our literature search yielded only 2 cases of myoclonus in relation to memantine, which has a different action with donepezil; to our knowledge, this is the first report of generalized myoclonus induced by donepezil overdosing. Based on the Naranjo probability scale it was probable that the patient’s myoclonus was related to donepezil because of clear temporal proximity and lack of alternative explanations. Conclusions: Clinicians should take into consideration therapeutic drug monitoring in the event of a potentially rare serious adverse reaction. Further studies are needed to clarify the possible role of donepezil in the pathophysiology of myoclonus.

Tiagabine-induced stupor in patients with psychogenic nonepileptic seizures: nonconvulsive status epilepticus or encephalopathy?

BACKGROUND

Nonconvulsive status epilepticus has been rarely reported with tiagabine (TGB) use.

METHODS

We report findings from continuous video-EEG monitoring and serial neurological examinations during prolonged episodes of stupor associated with TGB use in three patients who did not have epilepsy.

RESULTS

All three patients had emergence of new type of events after starting TGB treatment. All three patients had gradual decline in responsiveness to verbal stimuli, intermittent twitching of the upper extremities, and urinary incontinence. The corresponding EEG showed gradual build-up of generalized bisynchronous delta-wave activity with subsequent intermingled sharp transients. Two patients did not respond to IV lorazepam, one of whom also did not respond to IV phenytoin. The EEG slowly normalized in conjunction with associated clinical improvement. Habitual seizures were found to be psychogenic, with no interictal evidence for epilepsy.

CONCLUSION

Tiagabine-related stupor may represent a form of toxic encephalopathy in some cases rather than nonconvulsive status epilepticus.

Myoclonic status epilepticus in six patients without epilepsy

Myoclonic status epilepticus (MSE) is defined as prolonged period of myoclonic jerks that are correlated with epileptiform discharges on EEG. We here describe clinical features and video-EEG records of six adult patients with MSE who did not have a prior diagnosis of epilepsy. In four out of six patients, MSE was precipitated by drugs. Two out of four patients had chronic renal disease and received beta lactam group antibiotics. Two other patients, who described chronic pain, developed MSE while taking pregabalin. One patient who had dementia and family history of juvenile myoclonic epilepsy (JME) developed MSE one month after quetiapine was introduced. Another patient, who had a recent ischemic stroke, developed MSE due to an unknown reason. In these last two patients, an immediate triggering factor was not evident. Myoclonic status epilepticus ceased in five out of six patients after withdrawal of the drugs and/or intravenous antiepileptic treatment. Myoclonic status epilepticus is a rare event in patients without epilepsy. A correct diagnosis and prompt drug discontinuation may reverse this severe and life-threatening condition.

Myoclonus

Myoclonus can be classified as physiologic, essential, epileptic, and symptomatic. Animal models of myoclonus include DDT and posthypoxic myoclonus in the rat. 5-Hydrotryptophan, clonazepam, and valproic acid suppress myoclonus induced by posthypoxia. The diagnostic evaluation of myoclonus is complex and involves an extensive work-up including basic electrolytes, glucose, renal and hepatic function tests, paraneoplastic antibodies, drug and toxicology screens, thyroid antibody and function studies, neurophysiology testing, imaging, and tests for malabsorption disorders, assays for enzyme deficiencies, tissue biopsy, copper studies, alpha-fetoprotein, cytogenetic analysis, radiosensitivity DNA synthesis, genetic testing for inherited disorders, and mitochondrial function studies. Treatment of myoclonus is targeted to the underlying disorder. If myoclonus physiology cannot be demonstrated, treatment should be aimed at the common pattern of symptoms. If the diagnosis is not known, treatment could be directed empirically at cortical myoclonus as the most common physiology. In cortical myoclonus, the most effective drugs are sodium valproic acid, clonazepam, levetiracetam, and piracetam. For cortical-subcortical myoclonus, valproic acid is the drug of choice. Here, lamotrigine can be used either alone or in combination with valproic acid. Ethosuximide, levetiracetam, or zonisamide can also be used as adjunct therapy with valproic acid. A ketogenic diet can be considered if everything else fails. Subcortical-nonsegmental myoclonus may respond to clonazepam and deep-brain stimulation. Rituximab, adrenocorticotropic hormone, high-dose dexamethasone pulse, or plasmapheresis have been reported to improve opsoclonus myoclonus syndrome. Reticular reflex myoclonus can be treated with clonazepam, diazepam and 5-hydrotryptophan. For palatal myoclonus, a variety of drugs have been used.

Recurrent spinal myoclonus after two episodes of spinal anesthesia at a 1-year interval -A case report-

Spinal myoclonus is an unusual, self-limiting, adverse event that may occur during spinal anesthesia. The exact cause and underlying biochemical mechanism of spinal myoclonus remain unclear. A few cases of spinal myoclonus have been reported after administration of intrathecal bupivacaine. We report a case in which spinal myoclonus recurred after two episodes of spinal anesthesia with bupivacaine at a 1-year interval in a 35-year-old woman. The myoclonus was acute and transient. The patient recovered completely, with no neurologic sequelae.

Management of patients with myoclonus: available therapies and the need for an evidence-based approach

Myoclonus is a hyperkinetic movement disorder characterised by quick and involuntary jerks. Therapy should focus on cure of an underlying disorder; however, symptomatic treatment is often needed when treatment of an underlying cause is impossible or ineffective. The appropriate treatment for a specific type of myoclonus is based on the classification of the anatomical origin of the myoclonus: cortical, subcortical, spinal, or peripheral. We outline criteria for classification and present an overview of the available therapeutic options for the different types of myoclonus. Because of a generally low level of evidence, therapeutic options mainly rely on small observational studies and expert opinion. For an evidence-based approach in the future, randomised controlled trials of symptomatic therapies for myoclonus in homogeneous patient groups are needed.

Treatment options for epileptic myoclonus and epilepsy syndromes associated with myoclonus

BACKGROUND

Myoclonus is a brief shock-like movement that has many different etiologies. The degree to which it disturbs quality of life is extremely variable, as is its response to treatment.

OBJECTIVE

In this review, we focus on the treatment strategies for epileptic myoclonus in some common disorders, and in others that are not so common but where myoclonus is a prominent feature and has been studied more.

METHODS

An extended literature review in the English language was conducted through PubMed and text books.

CONCLUSION

Epileptic myoclonus is a manifestation of cortical irritability. The precise etiology is important when determining the best course of treatment. Response to treatment is variable and usually depends on the epileptic syndrome. Some antiepileptic drugs may worsen myoclonus even in patients with syndromes where most patients have a good response to that same drug. Therefore, clinicians must always have in mind that worsening in myoclonus may be ameliorated by decrease or withdrawal rather than increase of medication.

Levodopa-induced dyskinesias

Levodopa-induced dyskinesias (LID) are common and difficult to treat. This review focuses on three issues related to LID: clinical features, classification and rating, pathophysiology and pathogenesis, and management. The three primary clinical syndromes are OFF-period dystonia, peak-dose dyskinesia, and diphasic dyskinesia. Several other forms also occur, making the evaluation and choice of treatment complicated. A core component of the pathophysiology of LID is overactivity of the direct striatal output pathway. This pathway provides a direct GABAergic connection by which the striatum inhibits the output regions of the basal ganglia, i.e., the internal globus pallidus and the substantia nigra pars reticulata. Altering dopaminergic dosing and timing can abate dyskinesias, but usually impact the control of parkinsonism. Putative therapies to reduce the problem of dyskinesias could focus on the glutamatergic, GABAergic, alpha2 adrenergic, serotonergic (5HT1A, 5HT2A), opioid, histamine H3, adenosine A2A receptors, the monoamine transport or cannabinoid CB1 receptors systems. The only currently available drug with an evidence-based recommendation on efficacy for dyskinesia is amantadine. Therapy goals include the prevention of dyskinesia and treatment of dyskinesias that are troublesome clinically. New rating measures to assess severity and disability related to dyskinesia are in the process of development and clinimetric testing.

Drug-induced myoclonus: a French pharmacovigilance database study

Various drugs have been reported to induce myoclonus. However, this adverse event is not well known because of the difficult diagnosis and the lack of pharmaco-epidemiological or controlled studies. As far as we know, there are only case reports. In the literature, antiparkinsonian medications, antipsychotics, antidepressants, anesthetics, opiates and anti-infectious drugs have been reported in the occurrence of myoclonus. In a French pharmacovigilance database study, only 423 reports (0.2%) involved drug-induced myoclonus. The median age of patients was 55 years and 10% of these patients had a concomitant neurological disease. Only 16% of these reports had a strong imputability score (likely). The most frequently involved drugs were anti-infectious (15%), antidepressants (15%), anxiolytics (14%), and opiates agents (12%). Fifty-six percent of these reports were classified as serious adverse event. Concerning outcome, most patients (84%) recovered without sequels.