|Classification and external resources|
In the context of Parkinson's disease (PD), dyskinesia is often the result of long-term dopamine therapy. These motor fluctuations occur in up to 80% of PD patients after 5–10 years of L-DOPA treatment, Abstract with the percentage of affected patients increasing over time. Based on the relationship with levodopa dosing, dyskinesia most commonly occurs at the time of peak L-DOPA plasma concentrations and is thus referred to as peak-dose dyskinesia (PDD). As patients advance, they may evidence diphasic dyskinesia (DD), which occur when the drug concentration rises or falls. If dyskinesia becomes too severe or impairs the patient's quality of life, a reduction in L-Dopa might be necessary, however this may be accompanied by a worsening of motor performance. Therefore, once established, LID is difficult to treat. Amongst pharmacological treatment, N-methyl-D-aspartate (NMDA) antagonist, (a glutamate receptor), amantadine, has been proven to be clinically effective in a small number of placebo controlled randomized controlled trials, while many others have only shown promise in animal models. Attempts to moderate dyskinesia by the use of other treatments such as bromocriptine (Parlodel), a dopamine agonist, appears to be ineffective. In order to avoid dyskinesia, patients with the young-onset form of the disease or young-onset Parkinson's disease (YOPD) are often hesitant to commence L-DOPA therapy until absolutely necessary for fear of suffering severe dyskinesia later on. Alternatives include the use of DA agonists (i.e. ropinirole or pramipexole) in lieu of early L-DOPA use which delays the use of L-DOPA. Additionally, a review shows that highly soluble L-DOPA prodrugs may be effective in avoiding the in vivo blood concentration swings that potentially lead to motor fluctuations and dyskinesia.
Levodopa-induced dyskinesia (LID) have long been thought to arise through pathological alterations in pre-synaptic and post-synaptic signal transduction in the nigrostriatal pathway (dorsal striatum). It is thought that the stage of illness, the higher the dose and the frequency of L-Dopa treatment, and the younger the age of the patient at onset of symptoms, are considered to underlie the severity of the involuntary movements 
In experiments employing real time electrophysiological recordings in awake and behaving animals, LIDs have recently been shown to be strongly associated with cortical gamma-oscillations with accompanying Δc-fos overexpression proposedly due to a dysregulation of dopamine signaling in the cortico-basal ganglia circuitry, concluded partially from reduced TH staining in cortex and the fact that a dopamine receptor 1 antagonist delivered exclusively to the cortex relieved the dyskinesias at the time point of peak-dyskinesias.
ΔFosB overexpression in the dorsal striatum (nigrostriatal dopamine pathway) via viral vectors induces levodopa-induced dyskinesias in animal models of Parkinson's disease. Dorsal striatal ΔFosB is overexpressed in rodents and primates with dyskinesias; moreover, postmordem studies of individuals with Parkinson's disease that were treated with levodopa have also observed similar dorsal striatal ΔFosB overexpression.
Levetiracetam, an antiepileptic drug which has been demonstrated to reduce the severity of levodopa-induced dyskinesias, has been shown to dose-dependently decrease the induction of dorsal striatal ΔFosB expression in rats when co-administered with levodopa, although the signal transduction involved in this effect is unknown.
Patients with prominent dyskinesia resulting from high doses of antiparkinsonian medications may benefit from deep brain stimulation (DBS), which benefits the patient in two ways: 1) DBS allows a reduction in L-DOPA dosage of 50–60% (thus tackling the underlying cause); 2) DBS treatment itself (in the subthalamic nucleus or globus pallidus) can reduce dyskinesia.
- Gerlach, Manfred; Peter Riederer; Dieter Scheller (December 2011). "Mechanisms underlying and medical management of L-Dope-associated motor complications" (PDF). Journal of Neural Transmission. 118 (12): 1659–1660. doi:10.1007/s00702-011-0728-0. Retrieved 28 April 2012.
- Ahlskog JE, Muenter MD. Frequency of levodopa-related dyskinesias and motor fluctuations as estimated from the cumulative literature. Mov Disord. 2001;16:448-458.
- Obeso JA, et al. The evolution and origin of motor complications in Parkinson's disease. Neurology. 2000;55 (suppl 4):S13-S20.
- Thanvi, Bhomraj; Nelson Lo; Tom Robinson (2007). "Levodopa-induced dyskinesia in Parkinson's disease: clinical features, pathogenesis, prevention and treatment" (PDF). Postgraduate Medical Journal. 83 (980): 384–388. doi:10.1136/pgmj.2006.054759. PMC . PMID 17551069.
- Rascol, Olivier; Goetz C.; Koller W.; Poewe W.; Sampaio C. (May 2002). "Treatment interventions for Parkinson's disease: an evidence based assessment" (PDF). The Lancet. 359 (9317): 1589–1598. doi:10.1016/S0140-6736(02)08520-3. PMID 12047983. Retrieved 28 April 2012.
- Wolf, Elisabeth; Seppi,K.; Katzenschlager, R.; Hochschorner, G.; Ransmayr, G.; Schwinenschuh, P.; Ott, E.; Kloiber, I.; Haubenberger, D.; Auff, E.; Poewe, W. (2010). "Long-term antidyskinetic efficacy of amantadine in Parkinson's Disease". Movement Disorders. 25 (10): 1357–1363. doi:10.1002/mds.23034. Retrieved 28 April 2012.
- van Hilten J; Ramaker C; Stowe R; Nj Ives (2007). "Bromocriptine/levodopa combined versus levodopa alone for early Parkinson's disease". Cochrane Database Syst Rev. 4: CD003634.
- Stocchi F (2010). Clin Neuropharmacol. 33: 198. Missing or empty
- Cenci MA (2014). "Presynaptic Mechanisms of l-DOPA-Induced Dyskinesia: The Findings, the Debate, and the Therapeutic Implications". Front Neurol. 5: 242. doi:10.3389/fneur.2014.00242. PMC . PMID 25566170.
The dopamine (DA) precursor l-DOPA has been the most effective treatment for Parkinson's disease (PD) for over 40 years. The response to this treatment changes with disease progression, and most patients develop dyskinesias (abnormal involuntary movements) and motor fluctuations within a few years of l-DOPA therapy. There is wide consensus that these motor complications depend on both pre- and post-synaptic disturbances of nigrostriatal DA transmission.
- Halje, P; Tamtè, M; Richter, U; Mohammed, M; Cenci, MA; Petersson, P (21 November 2012). "Levodopa-induced dyskinesia is strongly associated with resonant cortical oscillations.". The Journal of neuroscience : the official journal of the Society for Neuroscience. 32 (47): 16541–51. doi:10.1523/jneurosci.3047-12.2012. PMID 23175810.
- Cao X, Yasuda T, Uthayathas S, Watts RL, Mouradian MM, Mochizuki H, Papa SM (May 2010). "Striatal overexpression of DeltaFosB reproduces chronic levodopa-induced involuntary movements". J. Neurosci. 30 (21): 7335–7343. doi:10.1523/JNEUROSCI.0252-10.2010. PMC . PMID 20505100.
- Du H, Nie S, Chen G, Ma K, Xu Y, Zhang Z, Papa SM, Cao X (2015). "Levetiracetam Ameliorates L-DOPA-Induced Dyskinesia in Hemiparkinsonian Rats Inducing Critical Molecular Changes in the Striatum". Parkinsons Dis. 2015: 253878. doi:10.1155/2015/253878. PMC . PMID 25692070.
Furthermore, the transgenic overexpression of ΔFosB reproduces AIMs in hemiparkinsonian rats without chronic exposure to L-DOPA . ... FosB/ΔFosB immunoreactive neurons increased in the dorsolateral part of the striatum on the lesion side with the used antibody that recognizes all members of the FosB family. All doses of levetiracetam decreased the number of FosB/ΔFosB positive cells (from 88.7 ± 1.7/section in the control group to 65.7 ± 0.87, 42.3 ± 1.88, and 25.7 ± 1.2/section in the 15, 30, and 60 mg groups, resp.; Figure 2). These results indicate dose-dependent effects of levetiracetam on FosB/ΔFosB expression. ... In addition, transcription factors expressed with chronic events such as ΔFosB (a truncated splice variant of FosB) are overexpressed in the striatum of rodents and primates with dyskinesias [9, 10]. ... Furthermore, ΔFosB overexpression has been observed in postmortem striatal studies of Parkinsonian patients chronically treated with L-DOPA . ... Of note, the most prominent effect of levetiracetam was the reduction of ΔFosB expression, which cannot be explained by any of its known actions on vesicular protein or ion channels. Therefore, the exact mechanism(s) underlying the antiepileptic effects of levetiracetam remains uncertain.
- Decamp E, Schneider JS (2009). "Interaction between nicotinic and dopaminergic therapies on cognition in a chronic Parkinson model". Brain Res. 1262: 109–14. doi:10.1016/j.brainres.2009.01.028. PMC . PMID 19368843.
- Louis Elan D.; Benito-León Julián; Bermejo-Pareja Félix (2008). "Population-Based Prospective Study of Cigarette Smoking and Risk of Incident Essential Tremor". Neurology. 70 (19): 1682–1687. doi:10.1212/01.wnl.0000311271.42596.32.
- Toda Hiroki; Hamani Clement; Lozano Andres (2004). "Deep Brain Stimulation in the Treatment of Dyskinesia and Dystonia". Neurosurg Focus. 17 (1): 9–13. doi:10.3171/foc.2004.17.1.2.