Oculomasticatory Myorhythmia, an Underrecognized Yet Key Finding for the Topographic and Etiological Diagnosis in Patients with Rhombencephalitis. Videographic Record of a Case

Oculomasticatory myorhythmia (OMM) is a hyperkinetic movement disorder, considered a rhythmic form of segmental myoclonus, ¹ consisting of repetitive, rhythmic and synchronous contractions of ocular and oromandibular muscles. It has a frequency between 1 and 4 Hz, ² appears at rest, persists with posture and activity, and usually overlaps with other movement disorders (Holmes tremor, Palatal Myoclonus). ² It has great value for topographic and etiological diagnosis, being highly specific for Whipple's disease (WD).

We present a 60‐year‐old male, previously asymptomatic, who developed polyarthralgia and unquantified weight loss for 1 year. Later on, he presented supranuclear gaze palsy, cerebellar syndrome (bilateral upper limb dysmetria, ataxic gait), and rapidly progressive clinical worsening, developing tetraparesis, stupor and different movement disorders in 2 weeks, including head tremor (possible Holmes Tremor) and OMM (Video 1).

Video 1.

This video highlights two movement disorders: Head tremor: low frequency (2–3 Hz), moderate amplitude tremor. Appears at rest, but is more evident with posture and action, disappears during sleep. These findings are suggestive of Holmes Tremor. OMM: A continuous, synchronous and rhythmic (low frequency, 2–3 Hz) movement disorder, involving lingual (tongue protrusion), buccal (opening‐occlusion movements), oculomotor (convergent nystagmus) and palpebral muscles (opening‐occlusion).

These symptoms (supranuclear gaze palsy, gait difficulties, impaired consciousness, OMM) pointed to a probable brain stem pathology. Brain MRI showed lesions in the midbrain, cerebellar peduncle and corpus callosum (Fig. 1), with homogeneous contrast uptake. Given the progressive course, cerebrovascular etiology seemed unlikely. Neurodegenerative diseases, like PSP, were ruled out due to the aggressive course and the absence of parkinsonism or midbrain atrophy (or any other characteristic neuroimaging findings). No vitamin deficiency was found, he had no history of alcoholism, so toxic‐metabolic entities (Alcoholic Cerebellar Degeneration, Marchiafava‐Bignami, Wernicke‐Korsakoff, etc.) were also ruled out.

FIG. 1.

T2 FLAIR hiperintensity in protuberance, midbrain, superior cerebellar peduncle and corpus callosum.

Given MRI findings, suggestive of encephalitis, we considered inflammatory (Multiple Sclerosis, NMO, Hashimoto Encephalopathy, anti‐NMDA, etc.) and infectious possibilities. Analytical study (including thyroid function, TPO and onconeural antibodies) was normal, CSF study showed proteins 47 mg/dL, leukocytes 28/mcL (78%PMN), normal glucose (60 mg/dL). PCR studies (Herpes Simplex etc.) were normal. Upon observation of OMM, T.Whipplei PCR in CSF is requested, resulting positive.

Final diagnosis was rhombencephalitis secondary to WD. Intravenous ampicillin (2 g/4 hours) treatment was completed for 4 weeks, with progressive motor improvement (being able to walk with a walker) and OMM resolution, persisting 20 months later. During recovery, we observed cognitive sequelae (mild dysexecutive syndrome). Whipple PCR in CSF 3 months after antibiotic completion was negative, so treatment was discontinued.

WD is an uncommon, systemic pathology, produced by Tropheryma whipplei, manifested as a chronic infection with digestive manifestations, preceded by prodromal symptoms (like polyarthralgia). Neurological affection (10%–43% ¹ of cases) includes the triad of cognitive impairment, ophthalmoplegia and myoclonus. ² , ³ Altered consciousness ² and motoneuron syndrome ¹ , ³ have also been described.

Diagnosis is based on clinical suspicion, with pathological confirmation. CSF Whipple PCR demonstrates CNS involvement (sensitivity/specificity of 97%). Treatment is based on long‐term antibiotics, its duration being highly controversial. ² , ³ , ⁴

Movement disorders are present in half of cases, ¹ being OMM a virtually pathognomonic finding ¹ , ⁵ although infrequent (8%–20% of cases). ¹ , ² Myorhythmia has been described in other entities (multiple sclerosis, cerebrovascular disease), ² associating lesions of the Guillain‐Mollaret triangle. ¹ , ² Different symptomatic treatments have been tried, ² showing moderate or no response, so etiological diagnosis and treatment are key for OMM resolution. ²

In conclusion, Neuro‐Whipple should be taken into account in the finding of OMM, as it is a potentially curable cause of encephalitis, with a fatal course in the absence of treatment.

Author Roles

(1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript: A. Writing of the first draft, B. Review and Critique.

D.L.D.: 1A, 1B, 1C, 2A, 2B, 2C, 3A, 3B

Y.S.B.: 1C, 2C, 3B

C.M.C.: 1C, 2C, 3B

M.P.C.: 1C, 2C, 3B

Disclosures

Ethical Compliance Statement

The authors confirm that the approval of an institutional review board was not required for this work. The patient of our publication was informed of the possibility of publication of his case. The patient understood and comprehended what was explained to him, in full cognitive abilities, and signed the informed consent. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Funding Sources and Conflicts of Interest

No specific funding was received for this work and the authors declare that there are no conflicts of interest relevant to this work.

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