Striatal Synaptic Dysfunction in Dystonia and Levodopa-Induced Dyskinesia.

This review provides an overview of the synaptic dysfunctions of neuronal circuits and underlying neurochemical alterations observed in the hyperkinetic movement disorders, dystonia and dyskinesia. These disorders exhibit similar changes in expression of synaptic plasticity and neuromodulation. This includes alterations in physical attributes of synapses, synaptic protein expression, and neurotransmitter systems, such as glutamate and gamma-aminobutyric acid (GABA), and neuromodulators, such as dopamine, acetylcholine, serotonin, adenosine, and endocannabinoids. A full understanding of the mechanisms and consequences of disruptions in synaptic function and plasticity will lend insight into the development of these disorders and new ways to combat maladaptive changes.

Acute Focal Dystonia After a Single Dose of Oral Cetirizine in a 9-Year-Old Boy.

Common cold is an acute illness affecting pediatric population in particular. The use of antihistamines is a common practice, with cetirizine being a frequently used drug with a good safety profile. However, adverse events due to the use of antihistamines have been rarely reported, such as drug-induced dystonia with the use of cetirizine. In our present case, dystonia due to the intake of cetirizine was observed, which the patient responded well to the use of benzodiazapines, namely, clonazepam. We report this case to highlight the occurrence of this adverse event with the use of cetirizine.

Pisa syndrome due to donepezil: pharmacokinetic interactions to blame?

We report a case of Pisa syndrome (PS) due to the acetylcholinesterase inhibitor donepezil which may have been precipitated by pharmacokinetic interactions with commonly used medications. PS is defined as a reversible lateral bending of the trunk with a tendency to lean to one side. This is a rare but very distressing complication with this commonly used medication which was not initially recognised, leading to increasing disability for the patient and significant carer stress. Cessation of donepezil and modulation of potential interacting medications resulted in complete resolution.

Acute dystonic reaction with rivastigmine.

Dystonic reactions are adverse extrapyramidal side effects and are common to antipsychotics, antiemetics, and a variety of other drugs. Rivastigmine, an anticholinesterase of carbamate variety, is well tolerated. A case of acute dystonic reaction with rivastigmine patch is being reported.

Top-Up Clozapine for Risperidone LAI-Related Acute Dystonia and TR Bipolar in an Adolescent with ID-Putting the Cart before the Horse?

Objectives: Young patients with intellectual disability (ID) have both diagnostic and therapeutic challenges. These include, inter alia, diagnostic overshadowing, diagnostic slippage and heightened vulnerability to adverse drug reactions. These would portent a generally poor prognostication. Methods: This is a case-study of an adolescent with intellectual disability long-hospitalized for co-morbid treatment-resistant bipolar mood disorder that failed to respond to ECT. Patient partially responded to LAI risperidone with repeated ADRs. Top-up with low-dose clozapine (100 mg/d) was pursued. Results: Low-dose clozapine top-up complemented therapeutic response (mood lability and paranoia) and strikingly safeguarded effectively against risperidone-related extrapyramidal side effects. Conclusions: Add-on clozapine remains a viable option, albeit off-label, in young patients with ID and treatment-resistant affective/schizophreniform psychoses. Clozapine has an edge over other agents in the setting of dyskinesias.

[Focal or Segmental Dystonia Resistant to Botulinum Toxin: How Do You Treat Patients in Whom Botulinum Toxin Treatment Has No Effect?]

Botulinum toxin treatment is most commonly used for blepharospasm, spastic torticollis, upper limb dystonia, and local dystonia in Japan. Botulinum toxin treatment is the first choice in these conditions. However, it has the disadvantages that the therapeutic effect is transient, that there are cases in whom the treatment is ineffective, and a high cost. In ineffective cases, botulinum toxin treatment involves medication and rehabilitation. Various medications have been used for the treatment of focal dystonia mainly in open trials. As these treatments have low evidence levels, each case should be dealt with individually. Operative treatment should be considered for severe cases.

Oculogyric crises secondary to lamotrigine overdosage.

We report four patients with no preexisting movement disorders who developed oculogyric crises secondary to lamotrigine toxicity and had resolution of these crises after dose reduction. Episode numbers ranged from 1-20 per day and episode duration from 2 s to several hours. Mean plasma concentration of lamotrigine at the time of oculogyric crisis was 15.5 µg/mL, with a mean dose of 16 mg/kg per day.

Out-of-hospital lingual dystonia resulting in airway obstruction.

This article discusses a case of antipsychotic-induced, focal lingual dystonia causing airway obstruction that was managed completely in the out-of-hospital environment by emergency medical services (EMS) providers. With the ever-increasing use of antipsychotic medications by the general population, it is important for EMS providers and emergency medicine physicians to be aware of rare presentations of dystonic reactions that can sometimes be life-threatening when they involve the lingual, pharyngeal, or laryngeal musculature. This article identifies the medications most likely to induce dystonic reactions, risk factors that predispose individuals to the development of dystonia, and the pathophysiology behind these adverse reactions. It also discusses differential diagnoses to consider, and emergent treatment options.

Gabapentin as a rescue drug in D-penicillamine-induced status dystonicus in patients with Wilson disease.

D-penicillamine induced status dystonicus is a unique but serious drug related complication in a subset of patients with Wilson disease. Patho-physiological basis of its occurrence is not known. It often responds poorly to anti dystonia medications. We present three patients with Wilson disease who developed severe paroxysmal dystonic spells after receiving D-penicillamine treatment. All three patients responded well to gabapentin after failing to respond to other anti dystonia drugs.

Frequency and risk factors of antibody-induced secondary failure of botulinum neurotoxin therapy.

OBJECTIVE: To investigate the risk factors of neutralizing antibody (NAB)-induced complete secondary treatment failure (cSTF) during long-term botulinum neurotoxin (BoNT) treatment in various neurologic indications. METHODS: This monocenter retrospective cohort study analyzed the data of 471 patients started on BoNT therapy between 1995 and 2015. Blood samples of 173 patients were investigated for NABs using the mouse hemidiaphragm test (93 with suspected therapy failure, 80 prospective study participants). The frequency of NAB-cSTF was assessed for various indications: hemifacial spasm, blepharospasm, cervical dystonia, other dystonia, and spasticity. A priori defined potential risk factors for NAB-cSTF were evaluated, and a stepwise binary logistic regression analysis was performed to identify independent risk factors. RESULTS: Treatment duration was 9.8 ± 6.2 years (range, 0.5-30 years; adherence, 70.6%) and number of treatment cycles 31.2 ± 22.5 (3-112). Twenty-eight of 471 patients (5.9%) had NAB-cSTF at earliest after 3 and at latest after 103 treatment cycles. None of the 49 patients treated exclusively with incobotulinumtoxinA over 8.4 ± 4.2 (1-14) years developed NAB-cSTF. Independent risk factors for NAB-cSTF were high BoNT dose per treatment, switching between onabotulinumtoxinA and other BoNT formulations (except for switching to incobotulinumtoxinA), and treatment of neck muscles. CONCLUSIONS: We present a follow-up study with the longest duration to date on the incidence of NAB-cSTF in patients treated with various BoNT formulations, including incobotulinumtoxinA. Whereas the overall risk of NAB-cSTF is low across indications and BoNT formulations, our findings underpin the recommendations to use the lowest possible dose particularly in cervical dystonia, and to avoid unnecessary switching between different formulations.

The basal ganglia and cerebellum interact in the expression of dystonic movement.

Dystonia is a neurological disorder characterized by excessive involuntary muscle contractions that lead to twisting movements or abnormal posturing. Traditional views place responsibility for dystonia with dysfunction of basal ganglia circuits, yet recent evidence has pointed towards cerebellar circuits as well. In the current studies we used two strategies to explore the hypothesis that the expression of dystonic movements depends on influences from a motor network that includes both the basal ganglia and cerebellum. The first strategy was to evaluate the consequences of subthreshold lesions of the striatum in two different animal models where dystonic movements are thought to originate from abnormal cerebellar function. The second strategy employed microdialysis to search for changes in striatal dopamine release in these two animal models where the cerebellum has been already implicated. One of the animal models involved tottering mice, which exhibit paroxysmal dystonia due to an inherited defect affecting calcium channels. In keeping with prior results implicating the cerebellum in this model, surgical removal of the cerebellum eliminated their dystonic attacks. In contrast, subclinical lesions of the striatum with either 6-hydroxydopamine (6OHDA) or quinolinic acid (QA) exaggerated their dystonic attacks. Microdialysis of the striatum revealed dystonic attacks in tottering mice to be associated with a significant reduction in extracellular striatal dopamine. The other animal model involved the induction of dystonia via pharmacological excitation of the cerebellar cortex by local application of kainic acid in normal mice. In this model the site of stimulation determines the origin of dystonia in the cerebellum. However, subclinical striatal lesions with either 6OHDA or QA again exaggerated their generalized dystonia. When dystonic movements were triggered by pharmacological stimulation of the cerebellum, microdialysis revealed significant reductions in striatal dopamine release. These results demonstrate important functional relationships between cerebellar and basal ganglia circuits in two different animal models of dystonia. They suggest that expression of dystonic movements depends on influences from both basal ganglia and cerebellum in both models. These results support the hypothesis that dystonia may result from disruption of a motor network involving both the basal ganglia and cerebellum, rather than isolated dysfunction of only one motor system.

Naloxone-responsive acute dystonia and parkinsonism following general anaesthesia.

Various movement disorders such as dystonia may acutely develop during or at emergence from general anaesthesia in patients with or without pre-existing Parkinson disease. These movements are triggered by a variety of drugs including propofol, sevoflurane, anti-emetics, antipsychotics and opioids. The postulated mechanism involves an imbalance between dopaminergic and cholinergic neurotransmitters in the basal ganglia. We report an acute, severe and generalised dystonic reaction in an otherwise healthy woman at emergence from general anaesthesia, dramatically reversed by the administration of naloxone, pointing to a potential role of the fentanyl and morphine that the patient had received. Recent literature on the mechanisms of abnormal movements induced by opioids are discussed. The severity of the reaction with usual doses of opioids, in a patient with no prior history of parkinsonism, led to further investigation that demonstrated the possibility of an enhanced susceptibility to opioids, involving a genetically determined abnormal function of glycoproteine-P and catechol-O-methyltransferase.

Acute onset of orofacial dystonia from promethazine treatment: A case report.

RATIONALE: Promethazine is an antihistamine agent used commonly for nausea and allergy. Along with its anticholinergic and antidopaminergic functions, promethazine is also used for psychiatric symptoms, such as troubling sleep, anxiety, and agitation. Previous studies have reported that promethazine may occasionally elicit acute dystonia in some individuals, especially for young children and pregnant women. PATIENT CONCERNS: The 68-year-old female patient was admitted to our hospital because of feeling anxious and intermittent palpitation for over 1 year. She developed acute orofacial dystonia following promethazine treatment. DIAGNOSES: Her diagnoses was generalized anxiety disorder. INTERVENTIONS: Discontinuation of the offending agent, promethazine, and injection of Botulinum toxin. OUTCOMES: The acute orofacial dystonia was finally alleviated by local injection of Botulinum toxin. LESSONS: Careful assessment of the risk of developing acute dystonia is also needed in old patients when initiating the promethazine treatment.

Acute cerebellar knockdown of Sgce reproduces salient features of myoclonus-dystonia (DYT11) in mice.

Myoclonus dystonia (DYT11) is a movement disorder caused by loss-of-function mutations in SGCE and characterized by involuntary jerking and dystonia that frequently improve after drinking alcohol. Existing transgenic mouse models of DYT11 exhibit only mild motor symptoms, possibly due to rodent-specific developmental compensation mechanisms, which have limited the study of neural mechanisms underlying DYT11. To circumvent potential compensation, we used short hairpin RNA (shRNA) to acutely knock down Sgce in the adult mouse and found that this approach produced dystonia and repetitive, myoclonic-like, jerking movements in mice that improved after administration of ethanol. Acute knockdown of Sgce in the cerebellum, but not the basal ganglia, produced motor symptoms, likely due to aberrant cerebellar activity. The acute knockdown model described here reproduces the salient features of DYT11 and provides a platform to study the mechanisms underlying symptoms of the disorder, and to explore potential therapeutic options.