课件：共济失调冯涛.pptVIP

（二）中枢性前庭损害 前庭神经核及其中枢联系的病变称为中枢性前庭损害。 见于多种原因所致的脑干病变时，表现为站立时向后或侧后方倾倒，与眼震慢相方向不一致，与头位无关，与自体的自发性偏斜方向不同。 因此中枢性前庭损害的特点是各种前庭反应不一致，症状亦较轻，诱发性前庭功能试验无障碍，可与周周围性前庭损害鉴别。 FRIEDREICH’S ATAXIA: CLINICAL PRESENTATION Typically the disease manifests around puberty and usually between 2-16 years. In most patients the presenting symptom is unsteadiness of gait. Alternatively the family may notice symptoms of generalised clumsiness or deterioration in athletic performance. Occasionally patients present with scoliosis and rarely with symptoms related to cardiomyopathy. The following diagnostic criteria are those of Harding et al. (Brain 1989 104:589-620) Seen in all patients: Progressive ataxia of limbs and gait Extensor plantar responses Nerve conduction studies showing motor velocities 40ms-1 in arms and absent sensory action potentials Dysarthria (often absent within 5 years of onset) Seen in more than two thirds of patients: Areflexia Scoliosis Pyramidal weakness in lower limbs Distal loss of joint position and vibration sense in lower limbs Abnormal electrocardiogram DIAGNOSIS A diagnosis can be made clinically, usually by a neurologist, with the support of nerve conduction studies and ECG. Genetic analysis is readily available through most genetic centres and is used as a confirmation of the diagnosis in patients, and is essential in doubtful cases. Isolated vitamin E deficiency can produce an identical clinical picture without gastroenterological symptoms, and vitamin E assay is therefore important. Further investigations are usually unnecessary for diagnosis, although may be necessary for full assessment. CEREBELLAR ATAXIA: Cerebellar ataxia can be thought of as a syndrome which has many different causes, the commonest in the UK being multiple sclerosis and alcoholic cerebellar disease. CLINICAL PRESENTATION These diseases can manifest mainly in adult life, but also in adolescence or childhood. Certain features differ between patients and may help in making a precise