Objective: We present the case of a 40 year old male alcoholic metal worker with 3 years of progressive ataxia of gait and palatal tremor.  Progressive ataxia with palatal tremor offers a broad differential and this case included multiple risk factors for disruption of the Guillain-Mollaret circuit.

Background: Progressive ataxia with palatal tremor (PAPT) is the syndrome of palatal myoclonus and progressive ataxia resulting from disruption of the guillain-mollaret circuit.The most common causes are stroke, trauma, demyelination, and posterior fossa tumors. Familial forms also exist but do not have olivary hypertrophy, and include Alexander disease, polymerase gamma mutation, and spinocerebellar atrophy. Treatments for symptomatic palatal tremor  include valproate, clonazepam, and trihexyphenidyl. There are no reported effective treatments to halt or prevent progression of the ataxia.

Method: This is a case presentation which is the result of a single meeting with an interesting patient seen in the movement disorders clinic.

Results: Exam showed a palatal tremor with synchronous vertical nystagmus with a torsional component. Gait was wide-based, ataxic with positive Romberg.  An MRI (figure 1) showed encephalomalacia and volume loss of bilateral posterior midbrain.  There was bilateral olivary hypertrophy in the medulla with increased T2 signal.

Conclusion: We felt this case unique because of the broad differential for potential causes of PAPT.  The finding of olivary hypertrophy on T2 imaging should prompt an investigation into its causes, which are typically a disruption of the Guillain-Mollaret triangle (dentato-rubro-olivary pathway), often at the level of the pons. A differential in this case should  include demyelination, neurodegeneration, toxic, and familial causes. This patient experienced hyponatremic coma preceding his symptoms and there is a possibility of central pontine myelinolysis during rapid correction. Toxic causes should include the possibility of heavy metal poisoning given his occupation, although the imaging findings are not typical for manganese or lead poisoning. The heavy alcohol use is also a risk factor for progressive ataxia, but palatal tremor is not typical, and a lack of vermian atrophy on imaging is also uncharacteristic.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/progressive-ataxia-with-palatal-tremor-in-a-metal-worker-with-possible-osmotic-demyelination/