Long-Term Management of a Refractory Corticosteroid Responsive Tremor Syndrome

A 2-year-old intact female Maltese dog was presented with generalized involuntary tremors and nystagmus without regular direction. The dog was conscious the whole time while it was trembling. Its involuntary tremors were alleviated at rest or during sleep. Magnetic resonance imaging (MRI) revealed asymmetric hydrocephalus and caudal occipital malformation. In cerebrospinal fluid (CSF) analysis, a trace of protein was found and total nucleated cell count (TNCC) was slightly increased. However, infectious pathogens were not found. In complete blood count, there was a mild leukocytosis. After the patient received anticonvulsants (midazolam, phenobarbital, KBr), diuretics (furosemide) with an anti-inflammatory drug (prednisolone, 0.5 mg/kg PO bid), and a proton-pump inhibitor (omeprazole), it showed no improvement. The patient was tentatively diagnosed with corticosteroid responsive tremor syndrome. So the anticonvulsants and diuretics were discontinued and the dose of prednisolone was increased to an immunosuppressive dose (1 mg/kg PO bid). After administering the immunosuppressive dose of prednisolone, the patient did not show nystagmus. Its tremors were much alleviated. However, they did not disappear. Five weeks later, the patient showed gradual improvement but still was trembling when moving around. Nine weeks later, its tremors were similar to before. So diazepam (0.3 mg/kg PO sid) was added to the treatment. After that, its tremors were alleviated more. Prednisolone and diazepam were maintained for about five months, with tapering of the dose of prednisolone (until 0.5 mg/kg PO sid). About 7 months later after the treatment was started, the dog was trembling rarely except when it was excited. Therefore, diazepam was discontinued. This case describes a refractory white dog shaker syndrome successfully managed with long-term administration of a steroid and diazepam.