There are two forms:

A few non-hereditary diseases formerly categorized as olivopontocerebellar atrophy have been reclassified as forms of multiple system atrophy as well as to four hereditary types, that have been currently reclassified as four different forms of spinocerebellar ataxia:

Diagnosis
A diagnosis of olivopontocerebellar atrophy (OPCA) may be based on a thorough medical exam; the presence of signs and symptoms; imaging studies; various laboratory tests; and an evaluation of the family history.MRI of the brain may show characteristics of OPCA, such as specific changes in the size of affected parts of the brain. This is more likely as the disease progresses; it is possible to have OPCA and have a normal brain MRI (especially within the first year of symptom onset).Hereditary OPCA may be suspected based on having a family history, and may be diagnosed by genetic testing (when available) for the condition suspected or known to be present in the family. Sporadic OPCA may be diagnosed if hereditary forms of OPCA, and other conditions associated with OPCA, have been ruled out. Treatment
Physiotherapy intervention aims to improve balance and gait of OPCA patients, by stimulating neuroplastic changes in the atrophied neural structure. A challenge-oriented treatment program has previously been shown to be beneficial for individuals with ataxia from OPCA. The treatment program was composed of repetitive training with task challenges (e.g. obstacle course) and/or novel motor skills acquisition over a 12-week period under the supervision of a physiotherapist.
Generally, the starting dose is oral spironolactone 100 mg/day (max 400 mg/day). 40% of people will respond to spironolactone. For nonresponders, a loop diuretic may also be added and generally, furosemide is added at a dose of 40 mg/day (max 160 mg/day), or alternatively (bumetanide or torasemide). The ratio of 100:40 reduces risks of potassium imbalance. Serum potassium level and renal function should be monitored closely while on these medications.Monitoring diuresis: Diuresis can be monitored by weighing the person daily. The goal is weight loss of no more than 1.0 kg/day for people with both ascites and peripheral edema and no more than 0.5 kg/day for people with ascites alone. If daily weights cannot be obtained, diuretics can also be guided by the urinary sodium concentration. Dosage is increased until a negative sodium balance occurs. A random urine sodium-to-potassium ratio of > 1 is 90% sensitivity in predicting negative balance (> 78-mmol/day sodium excretion).Diuretic resistance: Diuretic resistance can be predicted by giving 80 mg intravenous furosemide after 3 days without diuretics and on an 80 mEq sodium/day diet. The urinary sodium excretion over 8 hours < 50 mEq/8 hours predicts resistance.If the person exhibits a resistance or poor response to diuretic therapy, ultrafiltration or aquapheresis may be needed to achieve adequate control of fluid retention and congestion. The use of such mechanical methods of fluid removal can produce meaningful clinical benefits in people with diuretic resistance and may restore responsiveness to conventional doses of diuretics.