Olivopontocerebellar atrophy (OPCA) is the degeneration of neurons in specific areas of the brain – the cerebellum, pons, and inferior olivary nucleus. OPCA is present in several neurodegenerative syndromes, including inherited and non-inherited forms of ataxia (such as the hereditary spinocerebellar ataxia known as Machado–Joseph disease) and multiple system atrophy (MSA), with which it is primarily associated.OPCA  may also be found in the brains of individuals with prion disorders and inherited metabolic diseases. The characteristic areas of brain damage that indicate OPCA can be seen by imaging the brain using CT scans or MRI studies.The term was originally coined by Joseph Jules Dejerine and André Thomas. Signs and symptoms
OPCA is characterized by progressive cerebellar ataxia, leading to clumsiness in body movements, veering from midline when walking, wide-based stance, and falls without signs of paralysis or weakness. Clinical presentation can vary greatly between patients, but mostly affects speech, balance and walking. Other possible neurological problems include spasmodic dysphonia, hypertonia, hyperreflexia, rigidity, dysarthria, dysphagia and neck dystonic posture. Cause
Olivopontocerebellar atrophy is hereditary, but has an unknown genetic basis.
Specific activities that have been postulated as potential risk factors include intensive computer mouse use, trackball use, and typing, as well as some pastimes, including bowling, golf, fly-fishing, piano-playing, sewing, and knitting.Women are diagnosed more often than men. The syndrome commonly occurs during and, even more so, after pregnancy. Contributory factors may include hormonal changes, fluid retention and—again, more debatably and potentially harmfully—increased housework and lifting. Pathophysiology
De Quervain syndrome involves noninflammatory thickening of the tendons and the synovial sheaths that the tendons run through. The two tendons concerned are those of the extensor pollicis brevis and abductor pollicis longus muscles. These two muscles run side by side and function to bring the thumb away from the hand; the extensor pollicis brevis brings the thumb outwards radially, and the abductor pollicis longus brings the thumb forward away from the palm. De Quervain tendinopathy affects the tendons of these muscles as they pass from the forearm into the hand via a fibro-osseous tunnel (the first dorsal compartment). Evaluation of histopathological specimens shows a thickening and myxoid degeneration consistent with a chronic degenerative process, as opposed to inflammation. The pathology is identical in de Quervain seen in new mothers. Diagnosis
De Quervain syndrome is diagnosed clinically, based on history and physical examination, though diagnostic imaging such as X-ray may be used to rule out fracture, arthritis, or other causes, based on the persons history and presentation. The modified Eichoff maneuver, commonly called the Finkelsteins test, is a physical exam maneuver used to diagnose de Quervain syndrome.