Electromyographic assessment of paratonia
Many years after its initial description, paratonia remains a poorly understood concept. It is described as the inability to relax muscles during muscle tone assessment with the subject involuntary facilitating or opposing the examiner. Although related to cognitive impairment and frontal lobe function, the underlying mechanisms have not been clarified. Moreover, criteria to distinguish oppositional paratonia from parkinsonian rigidity or spasticity are not yet available. Paratonia is very frequently encountered in clinical practice and only semi-quantitative rating scales are available. The purpose of this study is to assess the feasibility of a quantitative measure of paratonia using surface electromyography. Paratonia was elicited by performing consecutive metronome-synchronized continuous and discontinuous elbow movements in a group of paratonic patients with cognitive impairment. Goniometric and electromyographic recordings were performed on biceps and triceps brachii muscles. Facilitatory (mitgehen) and oppositional (gegenhalten) paratonia could be recorded on both muscles. After normalization with voluntary maximal contraction, biceps showed higher paratonia than triceps. Facilitatory paratonia was higher than oppositional on the biceps. Movement repetition induced increased paratonic burst amplitude only when flexion and extension movements were performed continuously. Both facilitatory and oppositional paratonia increased with movement repetition. Only oppositional paratonia increased following faster movements. This is the first study providing a quantitative and objective characterization of paratonia using electromyography. Unlike parkinsonian rigidity, oppositional paratonia increases with velocity and with consecutive movement repetition. Like spasticity, oppositional paratonia is velocity-dependent, but different from spasticity, it increases during movement repetition instead of decreasing. A quantitative measure of paratonia could help better understanding its pathophysiology and could be used for research purposes on cognitive impairment.
KeywordsParatonia Frontal lobe Electromyography Cognitive impairment Spasticity Movements
Dr. Beversdorf is the Thompson Center William and Nancy Thompson Endowed Chair in Radiology.
Compliance with ethical standards
Conflict of interest
None of the authors have potential conflicts of interest to be disclosed.
- Dupré E (1910) Débilité mentale et débilité motrice associées. Rev Neurol (Paris) 20:54–56Google Scholar
- Hermens HJ, Roessingh Research and Development BV (eds) (1999) European recommendations for surface ElectroMyoGraphy: results of the SENIAM project. Roessingh Research and Development, EnschedeGoogle Scholar
- Lance JW (1980) Symposium synopsis. In: Feldman RG, Young RR, Koella WP (eds) Spasticity: disordered motor control. pp 485–494Google Scholar
- Mumenthaler M (1990) Neurology, 3rd edn. Thieme, StuttgartGoogle Scholar
- Strauss E, Sherman EMS, Spreen O, Spreen O (2006) A compendium of neuropsychological tests: administration, norms, and commentary, 3rd edn. Oxford University Press, Oxford, New YorkGoogle Scholar