Difference between revisions of "Eyelid myotonia"
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Revision as of 16:34, 18 July 2022
Myotonia is a disorder of the muscle membrane causing a kind of sustained muscle contraction, an inability to relax. (1, 2) Tone is normal when the muscles are relaxed, but contraction produces a temporary involuntary tonic persistence of muscle contraction with slow relaxation. Myotonia typically improves with repeated contractions, the warm up phenomenon, and may worsen in the cold or after prolonged rest. Paradoxical myotonia worsens after repetitive contraction.In grip myotonia, the patient has difficulty letting go of an object after gripping it strongly. Percussion myotonia is elicited by tapping on the muscle. Eyelid myotonia may cause transient difficulty opening the eyes after a forceful contraction or transient lid retraction after looking up.
Myotonia occurs in myotonic dystrophy types 1 and 2, the sodium channelopathies (hyperkalemic periodic paralysis and paramyotonia congenita), chloride channelopathies (myotonia congenita) and other conditions. The various conditions causing myotonia that are not DM1 or DM2 are sometimes referred to as the nondystrophic myotonias.
Testing in the patient shown in the video (courtesy of Constantine Farmakidis MD and Srijan Adhikari MD) showed a mutation in the SCN4A gene diagnostic of a sodium channelopathy, one of the nondystrophic myotonias.(3) Examination showed grip myotonia and prominent delayed relaxation of the eyelids after forced eye closure (eyelid myotonia)
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Hemiballismus (hemiballism) refers to a dramatic neurologic syndrome of wild, high amplitude, flinging, incessant movements that occur on one side of the body (Video). (1,2) It is classically due to infarction or hemorrhage in the region of the contralateral subthalamic nucleus (STN). Case series with modern neuroimaging have shown that only a minority of cases have lesions of the STN. Nonketotic hyperglycemia is also a common etiology. (3,4)
The movements of hemiballismus resemble those of chorea but are more pronounced. The clinical distinction between severe hemichorea and hemiballismus becomes arbitrary. Like chorea, hemiballistic movements are involuntary and purposeless, but they are much more rapid and forceful and involve the proximal portions of the extremities. When fully developed, there are continuous, violent, swinging, flinging, rolling, throwing, and flailing movements of the involved extremities. The movements are ceaseless during the waking state and disappear only with deep sleep. They are usually unilateral and involve one entire half of the body. Rarely, they are bilateral (biballismus or paraballismus) or involve a single extremity (monoballismus). The movements may spare the face and trunk. Hemiballismus is difficult to treat, incredibly disabling, and sometimes fatal because of exhaustion and inanition.
When hemiballismus results from a lesion of the contralateral STN, the damage to the STN removes its normal facilitation of the inhibitory effects of GPi/SNr. Without STN input, GPi/SNr inhibition of the motor thalamus decreases, causing increased thalamocortical activity and hyperkinesis.
Video legend. Patient with eyelid myotonia showing delayed relaxation of the eyelids after forced eye closure. Also note the full beard that the patient cites as helpful for mitigating facial muscle stiffening and pain in cold weather.
Video courtesy of Srijan Adhikari, Jeffrey Statland and Constantine Farmakidis, University of Kansas Medical Center.
References
1. Campbell WW. Clinical signs in neurology: a compendium. Philadelphia: Wolters Kluwer Health, 2016.
2. Roberts K, Kentris M. Myotonia. 2022 May 8. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 32644698.
3. Adhikari S, Statland J, Farmakidis C. Eyelid myotonia and face stiffness in skeletal muscle sodium channelopathy. RRNMF Neuromuscular Journal 2021:2;71-72.
