Electromyographic Patterns of Paratonia in Normal Subjects and in Patients with Mild Cognitive Impairment or Alzheimer’s Disease

Article type: Research Article

Authors: Marinelli, Lucio^{a; b; *} | Trompetto, Carlo^{a; c} | Puce, Luca^a | Monacelli, Fiammetta^{d; e} | Mori, Laura^{a; c} | Serrati, Carlo^f | Fattapposta, Francesco^g | Ghilardi, Maria Felice^h | Currà, Antonioⁱ

Affiliations: [a] Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genova, Italy | [b] IRCCS Ospedale Policlinico San Martino, Department of Neuroscience, Division of Clinical Neurophysiology, Genova, Italy | [c] IRCCS Ospedale Policlinico San Martino, Department of Neuroscience, Division of Neurorehabilitation, Genova, Italy | [d] Department of Internal Medicine, University of Genoa, Genova, Italy | [e] IRCCS Ospedale Policlinico San Martino, Department of Internal Medicine, Division of Geriatrics, Genova, Italy | [f] Department of Neurology, Imperia Hospital, Imperia, Italy | [g] Department of Human Neurosciences, Sapienza University of Rome, Roma, Italy | [h] Department of Physiology, Pharmacology & Neuroscience, CUNY School of Medicine, New York, NY, USA | [i] Department of Medical-Surgical Sciences and Biotechnologies, A. Fiorini Hospital, Terracina, LT, Sapienza University of Rome, Polo Pontino, Latina, Italy

Correspondence: [*] Correspondence to: Lucio Marinelli, MD, PhD, Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Largo Daneo 3, 16132 Genova, Italy. Tel.: +39 010 555 5648;E-mail: [email protected].

Abstract: Background:Information on prevalence, pathophysiology, and clinical assessment of paratonia are scarce. In a previous study, we suggested that surface electromyography (EMG) can be used to assess paratonia. Objective:To assess clinical and EMG features of paratonia in both patients with cognitive impairment and healthy subjects. Methods:We examined 18 patients with Alzheimer’s disease (AD), 21 patients with mild cognitive impairment (MCI), 30 healthy seniors (seniors), and 30 healthy juniors (juniors). Paratonia was assessed using the “Paratonia Scale”. EMG bursts were recorded from biceps and triceps during manually applied passive movements of elbow joint. Continuous (sinusoidal) and discontinuous (linear) movements were applied at 2 different velocities (fast and slow). Results:In comparison to juniors, seniors had higher clinical scores. In comparison to seniors, AD had higher oppositional scores, while MCI had higher facilitatory scores. EMG activity during passive movements correlated with paratonia clinical scores, was velocity-dependent and increased with movement repetition, most effectively for sinusoidal movements. Similar EMG activity was detected in not paratonic muscles. Conclusion:Paratonia increases with normal aging and cognitive decline progression. While facilitatory paratonia is due to involuntary contraction of the shortening muscle, oppositional paratonia is due, at least partially, to involuntary contraction of the lengthening muscle. Most characteristic feature of this muscle contraction is the progressive increase with movement repetition, that helps distinguish oppositional paratonia from spasticity and rigidity. A similar EMG activity is detected in not paratonic muscles, showing that, during tone assessment, the descending motor system is incompletely inactivated also in normotonic muscles.

Keywords: Alzheimer’s disease, cognitive impairment, dementia, frontal lobe, mild cognitive impairment, muscle tone, rigidity

DOI: 10.3233/JAD-215526

Journal: Journal of Alzheimer's Disease, vol. 87, no. 3, pp. 1065-1077, 2022