Vol.2, No.4, 108-112 (2013) Advances in Parkinson’s Disease http://dx.doi.org/10.4236/apd.2013.24020 Pseudoparkinsonism: A review of a common nonparkinsonian hypokinetic movement disorder Roger Kurlan*, Marcie L. Rabin Atlantic Neuroscience Institute, Overlook Medical Center, Summit, USA; *Corresponding Author: [email protected] Received 16 September 2013; revised 16 October 2013; accepted 24 October 2013 Copyright © 2013 Roger Kurlan, Marcie L. Rabin. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT [2-4]. Over time, clinicians learned that a variety of entities This article reviews the syndrome pseudopark- besides neuroleptic drugs can similarly cause a clinical insonism, a movement disorder described in the picture resembling that of PD. The notion that a parkin- literature that resembles parkinsonism but dif- sonian syndrome could be caused by cerebrovascular fers qualitatively. Patients with this disorder disease became popularized in the 1980’s and 1990’s. have apraxic slowness, paratonic rigidity, frontal Some publications referred to the condition as “vascular gait disorder and elements of akinesia that, pseudoparkinsonism” [5,6], similar to the term used for taken together, may be mistaken for true park- neuroleptic drugs. Other articles, in contrast, used the insonism. Pseudoparkinsonism appears to be term “vascular parkinsonism” to describe features with a common and is most often due to Alzheimer’s vascular etiology that are reminiscent of, but distinct disease or vascular dementia. It seems that pa- from, those found in PD. These include gait disorders tients with even mild cognitive deficits can pre- such as lower body parkinsonism, frontal-type gait dis- sent with pseudoparkinsonism and that the pri- orders and gait ignition failure [6]. The acute or subacute mary dementing disorder may be overlooked. onset of parkinsonism or pseudoparkinsonism has been The authors emphasize the importance of pseu- described in association with stroke involving specific doparkinsonism and implications for clinical dia- vascular territories [6]. Eventually, the term “parkinson- gnosis, treatment and research. ism” became used to describe the constellation of signs typically seen in PD, whether caused by PD itself or by Keywords: Parkinsonism; Pseudoparkinsonism; another etiology, thus replacing the term “pseudo park- Paratonia; Apraxia; Akinetic-Rigid Syndrome insonism”. Neuroleptic and other medication-induced forms are now generally referred to as “drug-induced 1. INTRODUCTION parkinsonism” and the vascular form is now termed “vascular parkinsonism” [7,8]. Non-degenerative causes History of the Pseudoparkinsonism of parkinsonism, such as drugs, cerebrovascular disease, Soon after the introduction of neuroleptic antipsy- infections, and others, have often been referred to collec- chotic medications in the 1950’s, it was recognized that tively as “secondary parkinsonism”. Other neurodegen- the dopamine receptor antagonist properties of these erative diseases that can resemble PD, such as progres- drugs could induce a clinical syndrome that resembled sive supranuclear palsy and multiple system atrophy, are Parkinson’s disease (PD). Consisting of hypomimia, hy- often referred to as “parkinson plus syndromes” or pophonia, drooling, resting tremor, rigidity, bradykinesia, “atypical parkinsonism” to denote the presence of true and a shuffling and unsteady gait, the condition was re- parkinsonian features while at the same time highlight ferred to as “pseudo-parkinsonism” [1] in order to dis- the presence of features considered atypical of idiopathic tinguish it from the neurodegenerative disease. In this PD. Some of these atypical features include symmetric case, the term “pseudo” implied a false or non-authentic motor dysfunction, absence of resting tremor, poor re- cause of features of PD. Over the next several decades, sponse to levodopa, and presence of certain characteris- “pseudo-parkinsonism” was used in many publications to tics such as prominent autonomic dysfunction, cerebellar denote the neuroleptic drug-induced movement disorder signs and early dementia. Copyright © 2013 SciRes. OPEN ACCESS R. Kurlan, M. L. Rabin / Advances in Parkinson’s Disease 2 (2013) 108-112 109 In 2000, we published an article [9] that discussed the bradykinesia (slowness or poverty of movement), and confusing literature on extrapyramidal parkinsonian signs thus closely resembles parkinsonism [16]. The physio- (slowness, rigidity, shuffling gait) being reported in pa- logical sequence effect of parkinsonian bradykinesia [22], tients with Alzheimer’s disease [10-15] and how the namely reduced starting force and progressive reduction proper classification of hypokinetic movement distur- of speed and amplitude which can be seen with repetitive bances required a careful consideration of not only their finger movements, would not be expected to be observed presence or absence but also their quality. Thus, we sug- in pseudoparkinsonism. Bedside or neurocognitive test- gested that the term “parkinsonism” should be reserved ing of praxis can also help distinguish apraxic slowness for conditions that showed the qualitative motor features from bradykinesia [9]. Rigidity in pseudoparkinsonism is of PD and were due to dysfunction of the nigrostriatal paratonia (gegenhalten; varying resistance to passive dopaminergic pathway. Parkinsonism includes bradyki- movement of a limb) [17]. The degree of resistance in nesia (slowness and paucity of movement), lead pipe paratonia typically depends on the speed of movement, (non-varying resistance to passive movement of a limb; usually being greater with faster movements and less or i.e., like bending a lead pipe) rigidity, resting tremor, absent with slower movements. In contrast, in parkin- postural imbalance, and a slow, shuffling gait. We further sonism the degree of resistance is not speed-dependent. suggested that the term “pseudoparkinsonism” be used The gait of patients with pseudoparkinsonism has been for the hypokinetic syndrome that superficially resem- described as a frontal (apraxic, cortical) gait disorder, bled PD but was qualitatively different (Table 1). The consisting of short steps, shuffling, “magnetic” (“glued “pseudo” component implies that the motor dysfunction to the floor”) qualities, start and turn hesitation and tran- resembles but is qualitatively not what occurs in PD or sient freezing, reduced arm swing, stooped posture and parkinsonism and is not related to nigrostriatal dysfunc- imbalance [6,18]. However, these are all also qualities tion, but rather to diffuse or multifocal cortical or sub- that can occur PD so they are not helpful in distinguish- cortical dysfunction. ing a frontal gait disorder from a parkinsonian gait [18]. The presence of festination and retropulsion, in contrast, 2. DISTINGUISHING are more characteristic of a parkinsonian gait while a PSEUDOPARKINSONISM FROM wide-based stance is more common in frontal gait disor- TRUE PARKINSONISM ders [17]. The frontal ataxia due to pseudoparkinsonism In both parkinsonism and pseudoparkinsonism patients can also be mistaken for the postural imbalance due to can appear slow, rigid and have a shuffling gait. In true the extrapyramidal etiology seen in true parkinsonism. parkinsonism, these clinical features are due to bradyki- Another important way of distinguishing true parkinson- nesia, lead pipe rigidity and parkinsonian gait. In pseu- ism from pseudoparkinsonism is that the motor features doparkinsonism, the similar clinical appearance is due to of the former generally respond to dopaminergic medica- apraxic slowness, paratonic rigidity and frontal gait dis- tions while those of the latter do not. Beyond apraxic slowness, paratonic rigidity and fron- order. Apraxia in pseudoparkinsonism is an inability to tal gait disorder, there are some additional phenomenol- perform or slowness (due to slowed cognitive processing) ogical considerations relevant to the identification of in performing skilled motor acts, such as dressing, eating, pseudoparkinsonism. Paratonic rigidity is often accom- or walking, despite intact primary neurological functions panied by mitgehen (“go with”), a phenomenon in which (comprehension of the task, motor strength, sensation the patient anticipates the movements and initiates them and coordination). Apraxia results from a disturbance of before the examiner. Mitgehen is not part of parkinson- cortical association function and can lead to the appear- ism. Although cogwheeling has been viewed as a specific ance of akinesia (the failure of willed movement to oc- sign of parkinsonism, this phenomenon can also occur cur), hypokinesia (reduced amplitude of movement) and when there is a combination of paratonic rigidity and Table 1. Parkinsonism vs. pseudoparkinsonism. essential tremor or myoclonus; thus, it can be seen in pseudoparkinsonism. Because myoclonus is common in Parkinsonism Pseudoparkinsonism patients with Alzheimer’s disease and vascular dementia, it is often seen in patients with pseudoparkinsonism. In Bradykinesia Apraxic slowness our experience, myoclonus that is very frequent can be Resting tremor Essential tremor, myoclonus mistaken for a resting tremor by referring physicians. Resting tremor has a predictable to-and-fro rhythmic Lead pipe rigidity Paratonic rigidity pattern, while myoclonus, when closely examined,