Diagnostic Approach to Cerebellar Ataxia and Dysautonomia

Clinical Presentation and Diagnosis

The combination of cerebellar ataxia and dysautonomia most strongly suggests Multiple System Atrophy (MSA), particularly the MSA-C subtype, where cerebellar symptoms predominate, or MSA-A, where autonomic dysfunction is most prominent 1, 2
MSA presents with cerebellar ataxia, pyramidal signs, and dysautonomia, including urinary incontinence, in the majority of cases, with typical onset between 55-65 years of age and mean disease duration of approximately 6 years 1, 2
MSA is a synucleinopathy with abnormal cytoplasmic inclusions of ubiquitin and alpha-synuclein in oligodendroglia, distinguishing it from tauopathies like PSP and CBD 1, 2
The majority of MSA cases exhibit Parkinsonian symptoms at some stage, though cerebellar and autonomic features may predominate depending on subtype 1, 2
PERM presents with muscle rigidity, stimulus-sensitive spasms, brainstem dysfunction, generalized myoclonus, hyperekplexia, cerebellar ataxia, and autonomic dysfunction 3
Some patients with PERM have GAD antibodies or glycine receptor antibodies (GlyR-Abs), with the latter showing better response to immunotherapy 3
Voltage-gated calcium channel antibodies (VGCC-Abs) are present in some cases of cerebellar degeneration associated with lung tumors 3
CASPR2 antibodies were identified in 10% of patients with idiopathic cerebellar ataxia compared to 2% in neurological controls 3

MRI of the head without IV contrast is the preferred initial imaging modality for evaluating cerebellar ataxia, as it provides superior visualization of the posterior fossa and can detect morphologic changes and signal alterations in the cerebellum and brainstem 5, 4, 6
If inflammatory or neoplastic causes are suspected, contrast-enhanced MRI should be included 5
Advanced MRI techniques such as diffusion-weighted imaging and spectroscopy may help detect early changes and distinguish between ataxia subtypes 5, 6
Test for GAD antibodies, glycine receptor antibodies (GlyR-Abs), CASPR2 antibodies, and VGCC antibodies in appropriate clinical contexts 3
Screen for underlying malignancy, particularly lung cancer, breast cancer, and SCLC in older patients with paraneoplastic presentations 3

Patients with GlyR-Abs and PERM respond well to immunotherapies including intravenous immunoglobulins, corticosteroids, and tumor removal if present 3
Early immunotherapy is critical to prevent permanent cerebellar damage in paraneoplastic syndromes 3
Balance training programs can improve stability in patients with cerebellar ataxia 5
Postural training can improve trunk control 5
Task-oriented upper limb training can improve reaching and fine motor control 5
Prescription of appropriate assistive devices and orthoses can improve balance and mobility 5