**6. Further diagnostic tests**

The following diagnostic tests as magnetic resonance imaging of the brain and spine, in addition to serum tests that can be indicated and guided by clinical and imaging evaluation, studies of the cerebrospinal fluid are obtained for paraneoplastic, immune-mediated, infectious and inflammatory disorders: protein, glucose, different blood count, cultures, IgG synthesis, index, rate; oligoclonal bands, cytology, lactate, 14-3-3 protein, paraneoplastic antibodies; viral encephalitis panel and Venereal Disease Research Laboratory test levels.


*Adapted from Evaluation and Management of Ataxic Disorders [27, p. 4].*

### **Table 2.**

*Workup for patients with ataxic disorders.*

In case of suspicion of occult malignancy, a CT scan or PET scan of the body may be indicated. Further diagnostic testing that may be helpful in certain situations includes electroencephalogram, electromyography, nerve conduction studies, autonomic studies, or sleep studies. In selected cases, nerve, muscle, and brain biopsies are used for suspected mitochondrial ataxias in leukodystrophies or idiopathic etiology. Other rarely indicated tests include magnetic resonance spectroscopy imaging of the brain and dopamine transporter single photon emission computed tomography (SPECT) (DaT) scan (abnormal in MSA-C and other specific illnesses). Specialized genetic testing for inborn errors of metabolism, leukodystrophies, and storage disorders should be ordered if the remainder of the evaluation raises suspicions about these rare conditions. The patient should be adequately counseled about the implications and costs of genetic testing before ordering [6, 27]. Several sporadic ataxias do not have an identified cause. When followed over time, about one-third of Idiopathic Late Onset Cerebellar Ataxia can progress to MSA-C. Unidentified genetic mutations may be responsible for the remainder of ataxias (**Table 2**) [28, 31].
