Is monoamine oxidase inhibitor induced myoclonus serotoninergically mediated?

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.

Association of serotonin transporter gene (5HTT) polymorphism and juvenile myoclonic epilepsy: a case-control study

Serotonin levels might alter susceptibility to seizures. Serotonin transporter (5HTT) gene polymorphisms were found to be associated with some forms of epilepsy. Here, we attempted to examine an association between 5HTT VNTR allele variants in a serotonin transporter gene and epileptogenesis in juvenile myoclonic epilepsy (JME) cases. We conducted a case-control candidate gene study evaluating the frequencies of 5HTT VNTR allele variants using SYBR green real-time PCR with melting curve analysis in JME patients and healthy subjects. Forty patients with JME were selected from the Epilepsy Outpatient Clinic of Kasr Al Ainy Hospital, Cairo University, who had been classified according to the electroclinical classification of the ILAE. The control group consisted of 40 healthy Egyptian subjects. The less efficient transcriptional genotypes for 5-HTT polymorphisms were more frequent in JME patients (OR 9.33, CI 2.85-30.60; p value < 0.001). In our study we detected an association between the presence of 5-HTTVNTR with less transcriptional efficient genotypes and JME, which suggests that modulation of the serotoninergic system might be indicated in epileptogenesis in JME.

Drug-induced myoclonus: frequency, mechanisms and management

Myoclonus is a sudden, abrupt, brief, 'shock-like' involuntary movement caused by muscular contractions ('positive myoclonus') or a sudden brief lapse of muscle contraction in active postural muscles ('negative myoclonus' or 'asterixis'). Various disorders can cause myoclonus including neurodegenerative and systemic metabolic disorders and CNS infections. In addition, myoclonus has been described as an adverse effect of some drugs. Level II evidence is available to indicate that levodopa, cyclic antidepressants and bismuth salts can cause myoclonus, while there is less robust evidence to associate numerous other drugs with the induction of myoclonus. The pharmacological mechanisms responsible for this adverse effect are not well established, although increased serotonergic transmission may be involved in the induction of myoclonus by several drugs. Drug-induced myoclonus usually resolves after withdrawal of the offending drug, but in some cases specific treatments are needed.

Approaching disturbed sleep in late Parkinson's Disease: first step toward a proposal for a revised UPDRS

A patient in stage 3-4 of the Unified Parkinson's Disease Rating Scale (UPDRS), or in stage 4-5 of Hoehn and Yahr staging scale, or a patient with 0-50% activities of daily living scale of Schwab and England is considered a Late Parkinson's Disease (LPD) patient. The prevalence of disturbed sleep in Parkinson's Disease (PD) was found to vary according to an objective rating, from 60 to 98%. The factors predicting the quality of life in PD patients are: depression, sleep disturbances and dependence. The present article proposes the insertion of the following items as a chapter in a revised UPDRS based on updated knowledge in sleep arousal disturbances in PD. V. SLEEP-AROUSAL DISTURBANCES: Sleep disturbances 43. Light fragment sleep (LFS) 44. Sleep-related breathing disorders (SRBD) 45. Restless legs-periodic leg movements during sleep (RLS-PLM) 46. REM behavioral disorders (RBD) 47. Sleep-related hallucinations (SRH) 48. Sleep-related psychotic behavior (SRPB) Arousal disturbances 49. Sleep attacks (SA) 50. Excessive daytime sleepiness (EDS). Approaching the treatment of disturbed sleep in LPD means postponement of the institutionalization of the LPD patient, allowing the spouse or the caregiver a quiet nights sleep. This approach consists of three steps, each one of major importance. (1) Correct diagnosis based on detailed anamnesis of the patient, of the spouse or of the caregiver; a one week recording on a symptom diary (log) by the patient or the caregiver; excluding co morbidities. Then choosing the most appropriate sleep test, if necessary: polysomnography (PSG), multiple sleep latency test (MSLT), multiple wake latency test (MWLT), actigraphy or video-PSG. This first step allows the diagnosis of one of the above mentioned sleep-arousal disturbances. (2) The non-specific therapeutic approach consists of: (a) checking the sleep effect on motor performance: beneficial, worse or neutral. (b) Dopaminergic adjustment is necessary due to the progression of the nigrostriatal degeneration and the increased sensitivity of the terminals which alter the normal modulator mechanisms of motor centers in LPD patients. Among the many neurotransmitters of the nigro-striatal pathway one can distinguish two with a major influence on REM and non-REM sleep. REM sleep corresponds to an increased cholinergic receptor activity and a decreased dopaminergic activity. This is the reason why REM sleep deprivation by suppressing cholinergic receptor activity ameliorates LPD motor symptoms. L-Dopa and its agonists by suppressing cholinergic receptors suppress REM sleep. L-Dopa has also an arousal effect on Non-REM sleep, repeatedly awakening the patient and enhancing the fragmentation due to the involuntary movements. (c) Socio-physical assistance. (3) The specific therapy consists of: LFS-Sinemet CR, Tolcapone, Intranasal Desmopressin, Domperidon, Cisapride and neurosurgery; SRBD-CPAP, UPPP, nasal interventions, losing weight; RLS-PLM-Benzodiazepine (Clonazepam), Opioid, Apomorphine infusion; RBD-Clonazepam and dopaminergic agonists; SRH-Clozapine, Risperidone; SRPD-Nortriptyline, Clozapine, Olanzepine; SA-adjustment; EDS-arousing drugs. Each therapeutic approach must be tailored to the individual LPD patient.

Sleep in Parkinson's disease

Two major sources of dissatisfaction with the quality of life among Parkinsonian patients are the "locomotor disability" and the "nature of their sleep". The main focus of research was directed towards the locomotor disability, but in the last two decades some progress has been made towards the understanding of sleep in PD patients. Sleep in Parkinson's disease is light and fragmented due to an increased skeletal muscle activity, disturbed breathing, impaired biological rhythm and REM-nonREM variations of the dopaminergic receptor sensitivity.

Dementia, myoclonus, peripheral neuropathy, and lipid-like material in skin biopsy during psychotropic drug treatment

Chronic treatment of humans with several drugs is associated with lesions resembling lipidosis in different tissues. Recently, a Creutzfeldt-Jacob-like syndrome has been observed during tricyclic antidepressant therapy, but no evidence of interaction of these drugs with lysosomal function has been reported during such treatment. We report a case of dementia, myoclonus, peripheral neuropathy, and lipid storage in the skin due to antidepressant drug therapy, in which the discontinuation of drugs resulted in an improvement of clinical and electrophysiologic signs together with reduction of morphological evidence of lipid lysosomal storage.

Somatosensory evoked potentials as indicators of altered cerebral excitability during psychotropic drug treatment

We observed an increase in the amplitude of the early cortical somatosensory evoked potentials (SSEPs) in five patients who developed myoclonus and/or generalized seizures during treatment with antidepressants. The increases correlated closely with the course of the clinical disturbances. In every case the SSEPs returned to normal values after the discontinuation of the psychotropic drugs. We suggest that SSEPs might help to identify and monitor patients who are at an increased risk of potentially hazardous side effects during psychopharmacological treatment.

Parkinsonian tremor loses its alternating aspect during non-REM sleep and is inhibited by REM sleep

Non-REM sleep transforms the waking alternating Parkinsonian tremor into subclinical repetitive muscle contractions whose amplitude and duration decrease as non-REM sleep progresses from stages I to IV. During REM sleep Parkinsonian tremor disappears while the isolated muscle events increase significantly.

Different laws govern motor activity in sleep than in wakefulness

A wide range of elementary and complex motor activities are known to occur during sleep, but very little is known about the basic physiologic condition of the skeletal muscle during sleep. The present study provides evidence that a minute electric random activity constitutes the basic physiologic condition of the skeletal muscles during sleep. During the NonREM stages of each sleep cycle a regression of the continuous random minute activity occurs, followed by a sudden increase of the isolated motor unit action potentials during REM sleep. Particular structural features of the anterior tibial (AT) muscle make it the most active skeletal muscle during sleep. During wakefulness, at rest, the random muscle activity disappears.