Pregabalin-induced cortical negative myoclonus in a patient with neuropathic pain

Detecting negative myoclonus during long-term home measurements using wearables

OBJECTIVE

The aim of this study was to develop a feasible method for the detection of negative myoclonus (NM) through long-term home measurements in patients with progressive myoclonus epilepsy type 1.

METHODS

The number and duration of silent periods (SP) associated with NM were detected during a 48 h home recording using wearable surface electromyography (EMG) sensors.

RESULTS

A newly developed algorithm was able to find short (50-69 ms), intermediate (70-100 ms), and long (101- 500 ms) SPs from EMG data. Negative myoclonus assessed by the algorithm correlated significantly with the video-recorded and physician-evaluated unified myoclonus rating scale (UMRS) scores of NM and action myoclonus. Silent period duration, number, and their combination, correlated strongly and significantly also with the Singer score, which assesses functional status and ambulation.

CONCLUSIONS

Negative myoclonus can be determined objectively using long-term EMG measurements in home environment. With long-term measurements, we can acquire more reliable quantified information about NM as a symptom, compared to short evaluation at the clinic.

SIGNIFICANCE

As measured using SPs, NM may be a clinically useful measure for monitoring disease progression or assessing antimyoclonic drug effects objectively.

Movement disorders associated with antiseizure medications: A systematic review

New-onset movement disorders have been frequently reported in association with the use of antiseizure medications (ASMs). The frequency of specific motor manifestations and the spectrum of their semiology for various ASMs have not been well characterized. We carried out a systematic review of literature and conducted a search on CINAHL, Cochrane Library, EMBASE, MEDLINE, PsycINFO, and Scopus from inception to April 2021. We compiled the data for all currently available ASMs using the conventional terminology of movement disorders. Among 5123 manuscripts identified by the search, 437 met the inclusion criteria. The largest number of reports of abnormal movements were in association with phenobarbital, valproic acid, lacosamide, and perampanel, and predominantly included tremor and ataxia. The majority of attempted interventions for all agents were discontinuation of the offending drug or dose reduction which led to the resolution of symptoms in most patients. Familiarity with the movement disorder phenomenology previously encountered in relation with specific ASMs facilitates early recognition of adverse effects and timely institution of targeted interventions.

Extracorporeal Treatment for Gabapentin and Pregabalin Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup

Toxicity from gabapentin and pregabalin overdose is commonly encountered. Treatment is supportive, and the use of extracorporeal treatments (ECTRs) is controversial. The EXTRIP workgroup conducted systematic reviews of the literature and summarized findings following published methods. Thirty-three articles (30 patient reports and 3 pharmacokinetic studies) met the inclusion criteria. High gabapentinoid extracorporeal clearance (>150mL/min) and short elimination half-life (<5 hours) were reported with hemodialysis. The workgroup assessed gabapentin and pregabalin as "dialyzable" for patients with decreased kidney function (quality of the evidence grade as A and B, respectively). Limited clinical data were available (24 patients with gabapentin toxicity and 7 with pregabalin toxicity received ECTR). Severe toxicity, mortality, and sequelae were rare in cases receiving ECTR and in historical controls receiving standard care alone. No clear clinical benefit from ECTR could be identified although major knowledge gaps were acknowledged, as well as costs and harms of ECTR. The EXTRIP workgroup suggests against performing ECTR in addition to standard care rather than standard care alone (weak recommendation, very low quality of evidence) for gabapentinoid poisoning in patients with normal kidney function. If decreased kidney function and coma requiring mechanical ventilation are present, the workgroup suggests performing ECTR in addition to standard care (weak recommendation, very low quality of evidence).

Pregabalin-associated stuttering and frequent blepharospasm: case report and review

Herpes zoster is an acute, painful, herpes skin disease caused by varicella-zoster virus, which may cause viral meningitis. Pregabalin has been shown to be efficacious in the treatment of pain in patients with herpes zoster. However, it has the side effects of neurotoxicity. We describe a 68-year-old female patient with herpes zoster, and she was treated with pregabalin. The patient presented with stuttering and frequent blepharospasm after 3 days of pregabalin treatment. Pregabalin was discontinued, the symptoms of stuttering and frequent blepharospasm completely resolved without any special treatment after one week. In this case, the etiology of stuttering and frequent blepharospasm may be related to pregabalin. Clinicians should be alert to the rare symptoms associated with the use of pregabalin.

Graphical abstract

Pregabalin-associated movement disorders: A literature review

Central nervous system adverse effects are commonly reported with pregabalin (PGB). On the other hand, movement disorders (MDs) associated with this drug were rarely described. However, their occurrence could significantly affect the quality of life of PGB users. This literature review aims to evaluate the clinical epidemiological profile, pathological mechanisms, and management of PGB-associated MDs. Relevant reports in six databases were identified and assessed by two reviewers without language restriction. A total of 46 reports containing 305 cases from 17 countries were assessed. The MDs encountered were as follows: 184 individuals with ataxia, 61 with tremors, 39 with myoclonus, 8 with parkinsonism, 1 with restless legs syndrome, 1 with dystonia, 1 with dyskinesia, and 1 with akathisia. The mean age was 62 years (range: 23-94). The male sex was slightly predominant with 54.34%. The mean PGB dose when the MD occurred was 238 mg, and neuropathic pain was the most common indication of PGB. The time from PGB start to MD was < 1 month at 75%. The time from PGB withdrawal to recovery was < 1 week at 77%. All the individuals where the follow-up was reported had a full recovery. The most common management was PGB withdrawal. In the literature, the majority of the cases did not report information about timeline events, neurological examination details, or electrodiagnostic studies. The best management for all MDs is probably PGB withdrawal. If the patient is on dialysis program, perhaps an increased number of sessions will decrease recovery time. Furthermore, the addition of a benzodiazepine could accelerate recovery.

Immediate and controlled-release pregabalin for the treatment of epilepsy

Introduction: Epilepsy is a common neurological disease requiring complex therapies, which are unable to achieve seizure control in 30% of patients. Poor adherence has been recognized as a possible determinant of drug-resistance. Prolonged-release formulations of antiepileptic drugs might help increase adherence and minimize side effects.Areas covered: Pregabalin (PGB) has peculiar pharmacodynamics and almost ideal pharmacokinetics, except for a short half-life and therefore requiring multiple daily dosing. PGB immediate-release (IR) is effective in focal-onset epilepsy (FOE), neuropathic pain, generalized anxiety disorder, and fibromyalgia, despite some tolerability issues, especially at higher doses. The controlled-release formulation (CR) shares PGB IR advantages and requires slight dose adjustments to guarantee bioavailability. In 2014, PGB CR (165 and 330 mg/day) failed to prove superior to placebo in a randomized placebo-controlled trial on 323 subjects with drug-resistant FOE, although it was just as tolerable. Therefore, PGB CR is not currently licensed for epilepsy.Expert opinion: Considering the disappointing results of the only controlled trial, PGB CR is unlikely to become an established epilepsy treatment anytime soon. Nevertheless, given its peculiar properties and potential advantages, PGB (in either formulation) should be further evaluated in specific populations of patients, especially fragile subjects with several comorbidities and complex polytherapies.

Negative myoclonus associated with pregabalin

Negative myoclonus (NM) is a jerky, shock-like involuntary movement caused by a sudden, brief interruption of muscle contraction. An 80-year-old man presented with multifocal NM and confusion. Two days before the onset of NM, he commenced the intake of pregabalin at a dose of 150 mg/day for neuropathic pain. His NM resolved completely and mental status improved gradually after the administration of lorazepam intravenously and the discontinuation of pregabalin. Our study suggests that pregabalin can cause NM even in patients without a history of seizures.

Negative myoclonus induced by gabapentin and pregabalin: A case series and systematic literature review

INTRODUCTION

Negative myoclonus is a jerky, brief, and sudden interruption of voluntary muscle contraction. Although gabapentin and pregabalin have been reported to induce positive myoclonus in some patients with impaired renal function, there are only a few studies describing pregabalin- or gabapentin-induced negative myoclonus. This study reviewed patients who had developed pregabalin- or gabapentin-induced negative myoclonus.

METHODS

We collected the patients with negative myoclonus who were referred to the department of neurology at a university-affiliated hospital and selected pregabalin- or gabapentin-induced negative myoclonus. Then reviewed the literature with respect to pregabalin- or gabapentin-induced negative myoclonus.

RESULTS

A total of 77 patients with negative myoclonus were reviewed. Among them, 21 neuropathic pain patients who were prescribed and developed negative myoclonus induced by pregabalin (9 cases) or gabapentin (12 cases). To prove causality of the drug, probable and certain level of category according to the WHO-UMC criteria were recruited. Of the 21 patients, 3 had impaired renal function, while 18 had normal renal function. Review of the literature identified 7 further cases (6 had normal renal function) with pregabalin- or gabapentin-induced negative myoclonus.

CONCLUSION

Pregabalin- and gabapentin-induced negative myoclonus can develop even in patients with normal renal function. Physicians should keep in mind the possibility of patients developing negative myoclonus under treatment of pregabalin or gabapentin even in short period of time and with low dosage, and in the normal range of renal function. Further prospective study investigating incidence and risk factors is warranted.

Myoclonus in the critically ill: Diagnosis, management, and clinical impact

Myoclonus is the second most common involuntary non-epileptic movement in intensive care units following tremor-like gestures. Although there are several types of myoclonus, they remain underappreciated, and their diagnostic and prognostic associations are largely ignored. This review discusses clinical, electrophysiological, neuroanatomical, and neuroimaging characteristics of different types of myoclonus in critically ill adults along with their prognostic impact and treatment options. Myoclonus is characterized by a sudden, brief, and sometimes repetitive muscle contraction of body parts, or a brief and sudden cessation of tonic muscle innervation followed by a rapid recovery of tonus. Myoclonus can resemble physiologic and other pathologic involuntary movements. Neurologic injuries, anesthetics, and muscle relaxants interfere with the typical appearance of myoclonus. Identifying "real myoclonus" and determining the neuroanatomical origin are important, as treatment responses depend on the involved neuroanatomical structures. The identification of the type of myoclonus, the involved neuroanatomical structures, and the associated illnesses is essential to direct treatment. In conclusion, the combined clinical, electrophysiological, and neuroradiological examination reliably uncovers the neuroanatomical sources and the pathophysiology of myoclonus. Recognizing cortical myoclonus is critical, as it is treatable and may progress to generalized convulsive seizures or status epilepticus.

Delayed onset of rotatory self-motion perception, dysdiadochokinesia and disturbed eye pursuit caused by low-dose pregabalin

A 30-year-old woman with chronic foot pain after an orthopaedic surgery and chronic neck pain presented to the emergency department (ED) with a history of self-rotatory vertigo with unsteadiness. She had started low-dose pregabalin, 25 mg two times a day 9 months before experiencing symptoms with the dose gradually increased to 150 mg two times a day over this period. Clinical examination revealed difficulty performing eye pursuit with left eye and dysdiadochokinesia of the left arm. Owing to a suspicion of multiple sclerosis she underwent cerebral MRI, which was normal. Pregabalin was tapered over 2 months with a complete disappearance of the symptoms. We concluded that symptoms were due to pregabalin treatment.

Pregabalin-associated myoclonic encephalopathy without evidence of drug accumulation in a patient with acute renal failure

Pregabalin, used for treating partial epilepsy and neuropathic pain, is usually well tolerated. Patients with impaired renal function are at risk to develop more serious adverse events. A 64-year-old woman was admitted in the Emergency Department for altered consciousness and abnormal movements. She recently started to take pregabalin (150 mg/day) for neuropathic pain. The drug was withdrawn 36 h before hospitalization following worsening of neurological symptoms. At physical examination, myoclonus was noted as main finding in the limbs and head, with encephalopathy. Laboratory investigations revealed acute renal failure with serum creatinine at 451.3 μmol/l. Urine output was preserved. After supportive care alone, myoclonus resolved after 24 h and consciousness was normal after 48 h. Renal function was also recovered. At the time of admission, the concentration of plasma pregabalin was 3.42 μg/ml, within therapeutic range. The calculated terminal elimination half-life was 11.5 h. Pregabalin-induced myoclonus may not be strictly related to drug accumulation in acute renal failure, with the possibility of a threshold phenomenon.

Pregabalin intoxication-induced encephalopathy with triphasic waves

This report documents the case of a 79-year-old woman presenting with encephalopathy and triphasic waves (TWs) due to pregabalin (PGB) intoxication. For the two years prior to admission, she had taken PGB to treat post-herpetic neuralgia. Brain MRI revealed mild leukoaraiosis and cortical atrophy. Electroencephalography showed continuous frontal-dominant TWs. These TWs were suppressed by intravenous lorazepam, but mental function was not improved. Laboratory tests revealed prerenal azotemia, which may elevate serum PGB and cause toxic encephalopathy with TWs. After fluid therapy and discontinuation of PGB, mental status recovered completely and TWs disappeared. I conclude that PGB intoxication due to deficient renal clearance can cause a reversible encephalopathy with TWs.

Resolution of pregabalin and mirtazapine associated restless legs syndrome by bupropion in a patient with major depressive disorder

Bupropion is a selective norepinephrine and dopamine reuptake inhibitor with no serotonergic activity, and is therefore an antidepressant with unique pharmacological properties. There are some reports that selective serotonin reuptake inhibitors (SSRIs) or mirtazapine can induce adverse effects including restless legs syndrome (RLS) and that bupropion can reverse these adverse effects. Here, we report about a patient with a major depressive disorder who exhibited RLS after being treated with pregabalin and mirtazapine. This adverse effect disappeared after having switched from mirtazapine to bupropion. Bupropion inhibits the reuptake of dopamine and increases dopamine neurotransmission in both the nucleus accumbens and the prefrontal cortex. This pharmacological profile can be effective in patients with RLS related to dopamine hypoactivity. However, the limitations of this single case report mean that further investigations with larger samples are needed.

Myoclonus

PURPOSE OF REVIEW

This review examines recent developments in the field of myoclonus.

RECENT FINDINGS

The range of clinical features in myoclonic dystonia has been extended and its underlying pathophysiology better defined. The diverse causes leading to jerky tremor and orthostatic myoclonus have been clarified and the need to consider drugs as potential causes highlighted. In patients with combined myoclonus and epilepsy, the major advance has been in our understanding of the natural history of these conditions, which can be more benign than hitherto thought. Finally, the new condition of primary progressive myoclonus of ageing has been identified, although it remains to be seen whether this is a pathological entity or not.

SUMMARY

Most progress has been in the characterization of myoclonic syndromes with dystonia and epilepsy. Therapeutic options remain limited, and exploration of the role of functional neurosurgery may be worthwhile in the future, given the debilitating nature of many myoclonic syndromes.

Pregabalin for the management of partial epilepsy

Pregabalin is one of the latest antiepileptic drugs introduced for the treatment of partial epilepsy. Its efficacy and safety as adjunctive therapy in refractory partial epilepsy have been established in four double-blind placebo-controlled trials (n = 1396) and 4 long-term open-label studies (n = 1480). In 3 fixed-dose trials, the proportion of patients with a >/=50% reduction in seizure frequency across the effective dose-range (150-600 mg/day) ranged between 14% and 51%, with a clear dose-response relationship. Suppression of seizure activity could be demonstrated as early as day 2. The most frequently reported CNS-related adverse events included dizziness, somnolence, ataxia and fatigue, were usually mild or moderate, and tended to be dose related. In long-term studies, weight gain was reported as an adverse event by 24% of patients. When pregabalin dose was individualized to according to response within the 150 to 600 mg/day dose range, tolerability was considerably improved compared with use of a high-dose, fixed-dose regimen (600 mg/day) without titration. In long-term studies up to 4 years, no evidence of loss efficacy was identified. During the last year on pregabalin, 3.7% of patients were seizure-free. Pregabalin appears to be a useful addition to the therapeutic armamentariun for the management of refractory partial epilepsy.