Oculomasticatory Myorhythmia

Key Points at a Glance

Highlights of This Disease

• Oculomasticatory myorhythmia (OMM) is a specific sign of central nervous system Whipple disease.
• It is characterized by the triad of slow (1–3 Hz) pendular convergent-divergent nystagmus, simultaneous contraction of the masticatory muscles, and supranuclear vertical gaze palsy.
• If OMM is present, empirical treatment for Whipple disease can be initiated without biopsy.
• Untreated, it leads to a fatal outcome. Long-term antibiotic therapy is essential.
• Whipple’s disease is an extremely rare condition with only about 1,000 cases reported in the literature worldwide.

1. What is Oculomasticatory Myorhythmia?

Oculomasticatory myorhythmia (OMM) is a pathognomonic clinical sign of central nervous system Whipple’s disease.

Whipple’s disease is a rare systemic bacterial infection caused by Tropheryma whipplei, which primarily infects macrophages in the small intestine, leading to malabsorption. To date, only about 1,000 cases have been reported in the literature, with a higher prevalence in men. Up to approximately 40% of patients with Whipple’s disease develop abnormal movements (including myoclonus, choreiform movements, and OMM), and the incidence of OMM is estimated to be about 20%.

The characteristics of OMM are the following three points.

• Pendular convergence-divergence nystagmus: Smooth, continuous low-velocity (1–3 Hz) nystagmus. It has larger amplitude and lower frequency than other pendular nystagmus.
• Simultaneous contraction of masticatory muscles: Rhythmic involuntary contractions synchronized with the nystagmus.
• Supranuclear vertical gaze palsy: Impaired upward or downward gaze.

When accompanied by rhythmic movements of the limbs, it is called oculofacial-skeletal myorhythmia (OFSM). OFSM is an expanded form of OMM that involves proximal and distal skeletal muscles, and both are specific to Whipple disease. Nystagmus may persist during sleep, which is also characteristic.

Q What is the difference between OMM and oculofacial-skeletal myorhythmia (OFSM)?

A

OFSM is an expanded form of OMM that includes involvement of skeletal muscles including the limbs. Both are specific signs of Whipple disease and may reflect differences in disease severity.

2. Main symptoms and clinical findings

Subjective Symptoms

• Oscillopsia: The pendular convergence-divergence nystagmus causes a sensation of the visual field shaking.
• Chewing difficulty: Due to involuntary rhythmic contractions of the masticatory muscles.
• Involuntary limb movements: In the OFSM type, rhythmic jerking of the limbs is present.
• Systemic symptoms (Whipple disease): Weight loss, steatorrhea, joint pain, and fever often precede other symptoms.
• Neurological symptoms: Dementia, lethargy, etc.

Clinical Findings

The main findings confirmed by the physician are as follows.

• Pendular convergence-divergence nystagmus (1–3 Hz): Slow, large-amplitude, smooth and sustained. ¹⁾
• Simultaneous rhythmic contraction of masticatory muscles: Synchronized with the nystagmus. ¹⁾
• Supranuclear vertical gaze palsy: Impaired vertical eye movements.
• Rhythmic movements of the limbs: Observed in some cases. ¹⁾
• Persistent eye movements during sleep: This finding is useful for differentiating from other nystagmus.

3. Causes and Risk Factors

The cause of OMM is central nervous system invasion by Tropheryma whipplei, which causes Whipple’s disease. This bacterium primarily infects small intestinal macrophages, leading to malabsorption.

In central nervous system invasion, lesions form in the midbrain and upper pons. The oculomotor nucleus, mesencephalic trigeminal nucleus, and limbic pathways are involved, and inflammatory infiltration manifests as rhythmic central discharges, resulting in nystagmus, jaw contractions, and limb jerks. ¹⁾

Epidemiologically, it is more common in men. An association with immunosuppressive states has been suggested, but no clear risk factors have been established.

Guidelines for early consultation

If you experience a combination of unexplained malabsorption, chronic joint pain, weight loss, and neurological symptoms (dementia, lethargy), please consider the possibility of Whipple’s disease and consult a medical institution.

4. Diagnosis and testing methods

OMM is a specific sign of Whipple disease, so recognizing OMM enables rapid diagnosis and initiation of treatment.

Diagnostic Criteria

According to the definitive diagnostic guidelines for Whipple disease, a definitive diagnosis is made if any one of the following three criteria is met.

Criterion 1

Presence of OMM or OFSM: This is a specific sign of Whipple disease and itself constitutes a diagnostic criterion.

Criterion 2

Positive tissue biopsy: Foamy macrophages (containing gram-positive bacilli) with positive periodic acid–Schiff staining are confirmed in duodenal or jejunal biopsy.

Criterion 3

Positive PCR analysis: Confirmation by PCR for T. whipplei or FISH (rRNA probe). Testing of central nervous system tissue can also detect asymptomatic CNS infection. ¹⁾

If OMM is present, biopsy confirmation is not mandatory to initiate empirical treatment.

Differential Diagnosis

Differential Diagnosis	Distinguishing Features
Oculopalatal myoclonus	Post-infarction of Guillain-Mollaret triangle. MRI shows hypertrophic olivary degeneration (not seen in OMM)
Anti-NMDA receptor encephalitis	Associated with ovarian teratoma. Positive for NMDA receptor antibodies
Holmes tremor / Parkinson’s disease	Without nystagmus

Oculopalatal tremor (OPT) occurs after lesions in the Guillain-Mollaret triangle (red nucleus, inferior olive, dentate nucleus) and shows inferior olivary hypertrophy on MRI. An important distinguishing point is that OMM lacks this lesion and does not involve inferior olivary hypertrophy.

Q If OMM is confirmed, can treatment be started without biopsy?

A

OMM is a specific sign of Whipple disease, so if OMM is confirmed, biopsy confirmation is not essential to initiate empirical treatment. However, confirmation of CNS WD by PCR or biopsy is also recommended. ¹⁾

5. Standard Treatment

Untreated Whipple disease has a fatal outcome. Early and long-term antibiotic therapy is essential.

Recommended Regimen

The main treatment options are shown below.

• Doxycycline + Hydroxychloroquine combination: Considered the most effective treatment regimen.
• Ceftriaxone (or Penicillin G) IV once daily for 2 weeks → TMP-SMX twice daily for 1 year: Alternative regimen.

Selection of antibiotics that can cross the blood-brain barrier (BBB) is important. Drugs that can cross the BBB include chloramphenicol, TMP-SMX, tetracycline, erythromycin, and ceftriaxone.

The minimum duration of treatment is unclear, but continuation for 12 months or more reduces the risk of recurrence. Neuro-ophthalmologic evaluation is recommended for all patients with Whipple disease.

Risk of Treatment Interruption

No treatment or treatment interruption directly leads to fatal outcomes. Self-discontinuation of long-term antibiotic therapy must be absolutely avoided. The risk of neurological sequelae increases upon relapse.

Q How long does treatment need to be continued?

A

The minimum treatment duration has not been established, but continuous treatment for 12 months or longer is thought to reduce the risk of recurrence. Without treatment, the condition is fatal, so long-term continuation of therapy is essential.

6. Pathophysiology and Detailed Mechanisms

The lesion sites in OMM are the brainstem (midbrain and upper pons) and the thalamus. ¹⁾ Inflammatory infiltration caused by T. whipplei damages the oculomotor nucleus, mesencephalic trigeminal nucleus, and limbic pathways, manifesting as rhythmic central discharge (rhythmic brainstem generator dysfunction). This discharge causes convergence-divergence nystagmus, jaw contractions, and limb jerks. ¹⁾

In contrast to oculopalatal tremor (OPT), which occurs after infarction of the Guillain-Mollaret triangle (red nucleus, inferior olive, dentate nucleus), OMM shows no lesions in this area and no hypertrophy of the inferior olive. This difference is useful for distinguishing between the two conditions.

Q How is OMM differentiated from oculopalatal tremor (OPT)?

A

OPT occurs after infarction of the Guillain-Mollaret triangle (red nucleus, inferior olive, dentate nucleus). MRI shows hypertrophy of the inferior olive, which is characteristic, but this finding is absent in OMM. Differentiation is based on the combination of the causative disease (brainstem infarction vs. Whipple disease) and imaging findings.

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7. Latest Research and Future Perspectives (Research-stage Reports)

For patients: Please read this carefully

The following content is currently at the research stage or in clinical trials, and is not standard treatment available at general hospitals. It is reference information for professionals regarding future medical developments.

Research reports on OMM itself are extremely limited. There are currently almost no specific treatment studies for OMM.

Gabapentin and memantine are considered effective for acquired pendular nystagmus (e.g., due to multiple sclerosis), and their application to OMM is at the research stage. ¹⁾ Advances in neuroimmunology and MRI diagnostic imaging are deepening the understanding of the mechanisms underlying involuntary eye movements in the brainstem, but there are no prospective large-scale studies on OMM, and further accumulation of evidence is awaited. ¹⁾

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8. References

1. Gurnani B, Kaur K, Kaur S, et al. Nystagmus: a comprehensive clinical review of classification, pathophysiology, diagnosis, and management. Clin Ophthalmol. 2025;19:1617-1650.