Introduction
Palatal myoclonus, more commonly referred to as palatal tremor, is an involuntary rhythmic movement disorder that affects the soft palate. It is broadly classified into two clinical forms: essential palatal tremor and symptomatic palatal tremor. Essential palatal tremor is often associated with an audible ear click and typically has a benign clinical course. Symptomatic palatal tremor is generally caused by a lesion in the brainstem, cerebellum, or their connecting pathways, and it is frequently accompanied by other neurological deficits such as nystagmus, oscillopsia, and ataxia. The following cases illustrate the varied presentations, diagnostic findings, and treatment approaches seen in clinical practice.
Clinical Features
The hallmark of palatal myoclonus is a rhythmic involuntary contraction of the soft palate muscles. In the essential form, the tensor veli palatini muscle is typically involved, and the movements often cease during sleep. Symptomatic palatal tremor characteristically involves the levator veli palatini muscle, may persist during sleep, and is frequently linked to damage along the dentato-rubro-olivary pathway. Additional symptoms can include ear clicks due to repetitive opening and closing of the Eustachian tube, dysphagia, dysarthria, and oscillopsia caused by concurrent ocular myoclonus.
Case 1: Essential Palatal Tremor with Disabling Ear Clicks
A 34-year-old woman presented with a two-year history of bilateral clicking sounds in her ears. The clicking was present while she was awake but stopped during sleep. Neurological examination was otherwise unremarkable, apart from rhythmic contractions of the soft palate. Magnetic resonance imaging of the brain was normal. Electromyography of the palatal muscles revealed repetitive bursts of activity in the tensor veli palatini muscle at a rate of approximately 120 beats per minute. Because the ear clicks caused significant distress, the patient was offered botulinum toxin type A injection into the tensor veli palatini under electromyographic guidance. The clicks resolved for four months, after which symptoms gradually returned and required repeat injections. This case reflects the typical course of essential palatal tremor, in which structural imaging is normal and symptomatic treatment is directed at the annoying ear click.
Case 2: Symptomatic Palatal Tremor after Pontine Hemorrhage
A 61-year-old man presented with a right-sided pontine hemorrhage causing vertigo, dysarthria, and left-sided limb weakness. Approximately three months later, he began to notice involuntary movements of his palate and persistent visual oscillation. Examination showed rhythmic elevation of the soft palate, bilateral gaze-evoked nystagmus, and mild appendicular ataxia. The palatal movements persisted during sleep. Magnetic resonance imaging demonstrated hemosiderin deposition in the pontine tegmentum, and T2-weighted images revealed hyperintensity within the hypertrophic right inferior olivary nucleus, a finding classically associated with hypertrophic olivary degeneration. The patient was treated with gabapentin and amitriptyline for oscillopsia, with partial symptomatic improvement. Clonazepam provided minimal additional benefit. This case emphasises the delayed appearance of palatal tremor after a brainstem injury and the importance of magnetic resonance imaging in identifying the underlying structural cause.
Case 3: Palatal Tremor as Part of a Progressive Ataxia Syndrome
A 48-year-old man developed progressive gait ataxia over several years and presented with a four-month history of ear clicking. Examination revealed palatal tremor, ocular flutter, and severe truncal ataxia. Magnetic resonance imaging showed cerebellar and brainstem atrophy without hyperintensity of the inferior olivary nucleus. Genetic testing identified a repeat expansion associated with a spinocerebellar ataxia phenotype. The palatal tremor was managed supportively with clonazepam, and the patient was referred for physical therapy and speech therapy. This case demonstrates that palatal myoclonus may occasionally be the presenting feature of a broader neurodegenerative disorder, and it highlights the need for careful longitudinal assessment.
Diagnostic Approach
The diagnosis of palatal myoclonus is primarily clinical and relies on the observation of rhythmic palatal movement. Magnetic resonance imaging of the brain is essential in all cases to exclude a structural lesion, particularly hypertrophic olivary degeneration along the dentato-rubro-olivary pathway. Electromyography can help confirm the presence of rhythmic muscle activation and differentiate the tensor veli palatini from the levator veli palatini pattern. The following table summarises the key differences between the two forms.
| Feature | Essential Palatal Tremor | Symptomatic Palatal Tremor |
|---|---|---|
| Muscle involved | Tensor veli palatini | Levitator veli palatini |
| Ear click | Prominent | Less prominent |
| Effect of sleep | Disappears during sleep | Persists during sleep |
| Magnetic resonance imaging | Usually normal | Hypertrophic olivary degeneration or brainstem lesion |
| Associated neurological signs | Absent | Ataxia, nystagmus, oscillopsia |
| Treatment response | Botulinum toxin is often effective | Treat underlying cause; medications may help |
Treatment Considerations
Treatment depends on the classification of the tremor. In essential palatal tremor with troublesome ear clicks, injection of botulinum toxin into the tensor veli palatini muscle is the most effective intervention. For symptomatic palatal tremor, management focuses on the underlying neurological disorder. Symptomatic medications reported to be of benefit include clonazepam, valproate, levetiracetam, and gabapentin, although responses vary. Patients with oscillopsia or disabling ataxia may require a multidisciplinary approach involving neurology, audiology, and physical therapy.
Conclusion
Palatal myoclonus is an uncommon movement disorder with two clinically distinct subtypes. Essential palatal tremor is generally benign and is most commonly treated with botulinum toxin for ear clicks, whereas symptomatic palatal tremor points to structural damage in the brainstem or cerebellar pathways and warrants thorough imaging and neurological evaluation. Recognition of the distinguishing features, as illustrated in the cases above, guides appropriate investigation and management.