Myorhythmia‐Like Dyskinesia Affecting the Face and Ear Associated With Anti–N‐Methyl‐d‐Aspartate Receptor Encephalitis

Involuntary ear movements are extremely uncommon and only a few cases have been reported.1, 2, 3, 4, 5 This unusual focal dyskinesia is characterized either as tic, dystonia, myoclonus, or chorea. Some cases are psychogenic, as suggested by temporally related psychological stresses, associated psychiatric symptoms, and improvement with psychological treatment.1 In other cases, there may be a temporal relationship with certain medications, such as paroxetine.3 Exceptionally, ear chorea has been described in a Huntington's disease patient.5

We report on a previously healthy 14‐year‐old male with anti–N‐methyl‐d‐aspartate receptor (anti‐NMDAR) encephalitis who developed involuntary left ear movements during the course of his disease. He was admitted after two generalized seizures. The EEG showed a focal slowness in the right frontal lobe without epileptic abnormalities. Brain MRI was normal, and he was discharged with valproic acid. Forty‐eight hours later, he presented to the emergency room with choreoatheoid movements in his left upper limb (see Video 1). Subsequently, there was a dramatic worsening of signs with left hemichorea and left orofacial dyskinesias. There were no abnormal movements on the right side of his body. Behavior changes were observed with mental slowness and progressive inhibition. After 3 days, his level of consciousness was severely impaired and he was admitted to the intensive care unit. Nevertheless, mild choreic movements persisted. At that time, an abnormal hyperkinetic movement on the left ear was noticed. It consisted in retraction of the ear, in an irregular and unpredictable way (less than 15 times per minute; see Video 2). There was an intermittent twitching of the left nasolabial fold as well. An extensive blood and cerebrospinal fluid (CSF) workup was performed. There was a mild mononuclear pleocytosis (100 cells/mm³), and CSF analysis identified anti‐NMDAR antibodies. A second brain MRI was normal. No tumor was identified. Treatment with corticosteroids followed by plasmapheresis and intravenous immunoglobulins resulted in marked clinical response. Encephalopathy improved progressively. Ear dyskinesia subsided in 1 week, despite the persistence of very subtle choreic movements involving his left hand. Two months later, he achieved complete recovery, and after 2 years' follow‐up, he has had no relapses.

To the best our knowledge, this is the first report of ear dyskinesia associated with anti‐NMDAR encephalitis. It is a treatable condition, and it resolved with immunotherapy. Movement disorders are very common during the course of the disease, and they have been reported in 84% of children with anti‐NMDAR encephalitis, even as an early feature. They consist mostly in orolinguofacial dyskinesias followed by choreoathetosis,6 and different abnormal movements may coexist in the same patient.7 The orofacial dyskinesias observed in this disorder have been described as “grimacing,” “chewing,” “facial twitching,” “tongue thrusting,” and other involuntary movements involving the face, mouth, and jaw that lack a proper terminology.8 The phenomenology of the hyperkinetic involuntary ear and facial movements in the present case is open to interpretation. Chorea is a random‐appearing sequence of discrete movements. It is distinguished from dystonia because of the apparently unpredictable, continuously ongoing nature of the movements compared with the more stereotyped movements or fixed postures of dystonia. When chorea affects proximal joints, such as shoulder or hip, this leads to large amplitude movements of the limbs called ballism. Myoclonus is characterized by repetitive and possibly rhythmic brief asymmetric shock‐like movements, whereas tremor is defined by rhythmic oscillating movements. Tics are stereotyped, predictable, and suppressible.9 In our patient, ear movements were unpredictable and not synchronous with, or of the same duration as, the simultaneous orofacial movements. Although they appeared in the same side of hemichorea, the anatomical location determined a resemblance to purposeless jerks, instead of chorea's dance‐like quality. The description may suggest myorhythmia. This is a repetitive, rhythmic, often jerky movement of slow (1–4 Hz) frequency, affecting mainly cranial and limb muscles. Its phenomenology overlaps with tremor, but it has a lower frequency, and it may have a jerky component characteristic of myoclonus.10 Ear movements in our case were not strictly rhythmic; therefore, we have preferred the term myorhythmia‐like dyskinesia.

The auricular muscles are vestigial in humans and are generally considered to be of little functional significance. Not many individuals can move their ears voluntarily. However, our patient was able to do it before and after his disease. That could partially explain the appearance of abnormal movements in such an atypical location. This case is linked to a well‐known disorder and widens the etiology of involuntary ear movements.

Author Roles

Manuscript: A. Writing of the First Draft; B. Review and Critique.

A.C.: A

N.N.: B

T.A.: B

R.S.: B

Disclosures

Funding Sources and Conflicts of Interest: The authors report no sources of funding and no conflicts of interest.

Financial Disclosures for previous 12 months: The authors declare that there are no disclosures to report.

Supporting information

Videos accompanying this article are available in the supporting information here.

Video 1. The patient presents choreoatheoid movements in his left upper limb associated with mild motor impersistence.

Video 2. The patient is unconscious and shows intermittent retraction of his left ear as well as mild nasolabial fold twitching.