Predominant cortical dysfunction in Guadeloupean parkinsonism
1Department of Physiology, Saint Antoine Hospital, AP-HP, 2INSERM U732, Saint-Antoine Hospital, 3Pierre and Marie Curie Medical School, Paris VI University, 4Department of Physiology, Groupe Hospitalier Pitié-Salpêtrière, AP-HP, 5INSERM, UMR_S 679, Neurology and Experimental Therapeutics, F-75013 Paris, 6Department of Neurology, Centre Hospitalier Universitaire, Pointe-à-Pitre, Guadeloupe, 7Federation of Neurology, Salpêtrière Hospital, AP-HP and 8CNRS UMR 7102, Paris VI University, Paris, France
Correspondence to: Annie Lannuzel, INSERM U679, 47 Bd de l'Hôpital, 75013 Paris, France; Department of Neurology, University Hospital of Pointe-à-Pitre, BP465, 97 159 Pointe-à-Pitre Cedex, Guadeloupe, F.W.I. E-mail: annie.lannuzel{at}wanadoo.fr
Atypical parkinsonism is extremely frequent in Guadeloupe and may have an environmental cause. One-half of the patients with this tauopathy have dopa-resistant parkinsonism, tremor, subcortical dementia and abnormal eye movements suggestive of progressive supranuclear palsy (PSP). They also have hallucinations, dysautonomia, which are not characteristic of PSP. Furthermore, the oculomotor abnormalities and the tremor, which is jerky, differ from what is observed in classical PSP patients. We therefore undertook an electrophysiological study to characterize these features in greater detail. Nine representative Guadeloupean PSP-like (Gd-PSP) patients were selected for electro-oculographic recordings of horizontal eye movements [visually guided saccades (VGS), antisaccades (AS) and smooth pursuit], clinical evaluation of vertical saccade velocity and electrophysiological analysis of abnormal limb movements [electromyographic polygraphy, EEG jerk-locked-back-averaging (JLBA) and long-loop C-reflex]. Vertical saccade velocity was reduced in five patients. The velocity of horizontal VGS was normal, although the latencies were increased and horizontal smooth pursuit (HSP) was mostly saccadic. The AS error rate was above 70% in most patients. Myoclonus was detected in 89% of the Gd-PSP patients. It was mainly small amplitude rest and action myoclonus in the upper limbs, characterized by short arrhythmic 24–76 ms bursts and was of cortical origin, as confirmed by JLBA in five patients. In conclusion, Gd-PSP patients have cortical myoclonus and cortical oculomotor impairments, but only minor signs of brainstem oculomotor dysfunction, suggesting that cortical dysfunction predominates over brainstem impairments. This electrophysiological study, added to previous clinical, neuropsychological and neuroradiological studies, has enriched the characterization of Guadeloupean atypical parkinsonism, which thus appears to be a new clinical entity.
Key Words: myoclonus; eye movements; Guadeloupean parkinsonism; taupathy; PSP
Abbreviations: Acc, accelerometer; AS, antisaccades; CBD, cortico-basal degeneration; DLB, dementia with Lewy bodies; ECR, extensor carpi radialis; EMG, electromyographic; FAB, frontal assessment battery; FCR, flexor carpi radialis; 1DIO, 1st dorsal interosseous; Gd-PSP, Guadeloupean progressive supranuclear palsy; HSP, horizontal smooth pursuit; JLBA, EEG jerk-locked-back-averaging; LLCR, long-loop C-reflex; MMSE, mini-mental status examination; MSA, multiple system atrophy; PSP, progressive supranuclear palsy; PSP-P, PSP-parkinsonism; RBD, REM sleep behaviour disorder; REM, rapid eye movement; RS, Richardson's syndrome; SAM, small amplitude myoclonus; SWJ, square wave jerks; UPDRS, unified Parkinson's disease rating scale; VGS, visually guided saccades
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Received April 26, 2008. Revised August 8, 2008. Accepted August 11, 2008.
*These authors contributed equally to this work.