脊髓小脑共济失调（SCA）是一组遗传性、渐进性、退行性且常常是致命的疾病，其特征包括言语、眼球运动和四肢运动的协调能力差，以及步态不稳和平衡能力差。这些疾病由影响小脑（大脑控制协调和平衡的部分）的基因突变引起。

脊髓小脑共济失调的类型
脊髓小脑共济失调有许多类型，通常根据与之相关的特定基因突变进行分类。每种类型根据发现的顺序依次编号，例如，SCA1、SCA2、SCA3等。到目前为止，已经识别出40多种基因上有区别的类型。

父病和子病
• **父病：**脊髓小脑共济失调是更广泛的疾病类别——小脑共济失调疾病的一种类型，这些疾病影响小脑和脊髓。
• **子病：**每个具体的类型（例如，SCA1、SCA2、SCA3等）可以被视为脊髓小脑共济失调的“子病”。

同义词
脊髓小脑共济失调也被称为：
• 脊髓小脑变性
• 橄榄脑桥小脑萎缩（当具体指涉到涉及这些额外大脑区域的类型时）

为了鉴别诊断脊髓小脑共济失调（SCA），需要采用综合方法，涉及多种类型的病人信息和测试结果。以下是通常所需的内容：
1. 症状： 患者症状的详细描述，如动作不协调、步态障碍、精细运动任务困难、言语含糊和眼球运动异常。
2. 病史： 家族病史信息，特别是任何有类似症状或已诊断为神经系统疾病的亲属，这可以指示遗传性共济失调。个人病史包括症状开始、进展和可能导致共济失调的毒素或药物接触情况。
3. 体格检查： 神经系统检查，以评估反射、肌肉力量、肌张力、触觉和协调能力。这有助于评估小脑受累程度和其他神经损害。
4. 诊断测试：
• 遗传测试： 识别与不同类型的SCA相关的特定基因突变。
• 磁共振成像（MRI）： 检查小脑萎缩或大脑其他结构变化。
• 血液测试： 排除可能模仿共济失调的其他疾病，如维生素缺乏（例如，维生素E或B12）、甲状腺功能异常或感染。
• 电生理研究： 如神经传导研究和肌电图，以排除周围神经系统疾病。
5. 附加测试： 根据初步发现，可能需要进行额外评估。例如，腰椎穿刺分析脑脊液（CSF）可以帮助排除影响中枢神经系统的炎症或感染过程。

共济失调（SCA）是一种进展性遗传性疾病，其特征是由于小脑及其相关通路的退化而导致协调和平衡能力的丧失。共济失调的诊断通常包括病史收集、体格检查和诊断测试的结合：
1. 病史收集：
• 家族史： 由于SCA是遗传性的，因此详细的家族史，包括类似症状或已知遗传疾病的记录非常关键。
• 症状的开始和进展： 症状开始的年龄以及它们随时间的进展情况。
2. 体格检查：
• 神经系统检查： 包括协调性、步态、言语（构音障碍）、眼球运动和反射的测试，有助于评估小脑受累的程度。
• 运动技能评估： 对精细运动、平衡和协调的评估。
3. 诊断测试：
• 遗传测试： 对于SCA来说，这是最确定的测试，可以识别导致该病症的特定遗传突变。
• MRI或CT扫描： 影像学检查可以显示小脑及大脑其他区域的变化。
• 肌电图（EMG）和神经传导研究： 这些测试评估肌肉的电活动和神经信号的传导速度。
每个患者的结果会根据具体的SCA类型和其他个人因素而有所不同。

与SCA3亚型（也称为Machado-Joseph病，MJD）相关的特定基因突变是ATXN3基因中的CAG三核苷酸重复扩展。该基因位于染色体14q32.1上。在ATXN3基因中的CAG重复的正常范围是12到44，但在SCA3患者中，重复次数通常扩展到55到86或更多。

病历记录

病人ID: 00112233
出生日期: 1970年1月1日
就诊日期: 2024年5月1日

主诉:
过去两年内平衡和协调能力逐渐下降。
症状:
• 行走不稳
• 经常绊倒
• 细微动作困难，如扣衬衫纽扣和书写
• 语言不清
• 偶尔复视
病史:
• 无神经系统疾病家族史
• 五年前诊断为高血压，目前正在用药物控制
• 无重大头部创伤或毒素暴露史
体格检查:
• 步态异常，步伐宽大且不协调
• 罗姆博格征阳性
• 在指鼻试验中观察到运动失调
• 感觉检查正常
• 肌肉力量正常，但协调性下降
诊断测试:
• 大脑MRI：轻度小脑萎缩，未见中风或肿瘤证据
• 遗传测试：正在等待与脊髓小脑共济失调类型1、2、3、6、7相关的突变结果
• 完全血细胞计数和代谢组：均在正常范围内
鉴别诊断:
1. 脊髓小脑共济失调
2. 多发性硬化症
3. 中风
4. 维生素B12缺乏
5. 慢性酒精中毒

小腦脊髓運動障礙（SCA）是一種進行性的退行性疾病，其特徵是協調問題和行走困難。以李先生為例，他是一位55歲的男性，他呈現出越來越難以保持平衡的一年歷史，導致頻繁跌倒。他的家人注意到他在協調手部動作和說話含糊不清方面也有困難。神經學檢查顯示他的眼動不規則、急促，四肢協調能力受損，與小腦共濟失調相符。基因檢測確認了他患有第3型小腦脊髓運動障礙，這是一種常染色體顯性遺傳。醫生建議李先生進行治療性運動，並就家中的安全改進措施提供指導，以減少跌倒的風險。

脊髓小脑共济失调 (SCA) 涉及一组进展性神经退行性疾病，其特点是多种症状，主要影响协调和步态。诊断SCA时，考虑可能表现出类似症状的其他疾病是确保准确诊断的关键。以下是在鉴别诊断中应考虑的几种疾病：
1. 多发性硬化症 - 一种影响大脑和脊髓的自身免疫疾病，导致与SCA相似的运动和感觉障碍。
2. 弗雷德里希共济失调 - 一种遗传性疾病，导致神经系统逐渐受损，表现出与SCA相似的共济失调和其他神经症状。
3. 威尔逊病 - 一种遗传性疾病，导致体内铜积累过多，可能导致与SCA相似的神经症状。
4. 维生素E或B12缺乏 - 这些维生素的缺乏可导致神经系统症状，包括共济失调。
5. 脑肿瘤或中风 - 小脑的肿瘤或缺血性损伤可表现出共济失调，需要排除。
6. 其他遗传性共济失调 - 如共济失调-毛细血管扩张症或常染色体隐性小脑共济失调，可能与SCA有类似的表现。

Spinocerebellar ataxia (SCA) refers to a group of hereditary, progressive, degenerative, and often fatal disorders characterized by symptoms including poor coordination of speech, eye movements, and limb movements, along with unsteady gait and poor balance. These disorders are caused by genetic mutations that affect the cerebellum—the part of the brain that controls coordination and balance.

Types of Spinocerebellar Ataxia
There are numerous types of SCA, and they are often classified by the specific gene mutation they are associated with. Each type is numbered sequentially based on the order of discovery; for example, SCA1, SCA2, SCA3, etc. There are more than 40 genetically distinct types identified so far.

Parent and Child Diseases
• Parent Disease: Spinocerebellar ataxia is a subtype of a broader category of diseases known as cerebellar ataxias, which affect the cerebellum and the spinal cord.
• Child Diseases: Each specific type (e.g., SCA1, SCA2, SCA3, etc.) can be considered a 'child disease' under the umbrella of spinocerebellar ataxia.

Synonyms
Spinocerebellar ataxia is also known as:
• Spinocerebellar degeneration
• Olivopontocerebellar atrophy (when specifically referring to types that involve these additional regions of the brain)

To differentially diagnose spinocerebellar ataxia (SCA), a comprehensive approach involving various types of patient information and test results is needed. Here’s what is typically required:
1. Symptoms: Detailed account of the patient's symptoms such as uncoordinated movements, gait disturbances, difficulty with fine motor tasks, slurred speech, and eye movement abnormalities.
2. Medical History: Information on family medical history, especially any relatives with similar symptoms or diagnosed neurological disorders, which can indicate a hereditary form of ataxia. Personal medical history including onset of symptoms, progression, and exposure to possible toxins or medications that could cause ataxia.
3. Physical Examination: A neurological examination to assess reflexes, muscle strength, muscle tone, sense of touch, and coordination. This helps to evaluate the extent of cerebellar involvement and other neurological impairments.
4. Diagnostic Tests:
• Genetic Testing: To identify specific genetic mutations associated with different types of SCA.
• MRI (Magnetic Resonance Imaging): To check for cerebellar atrophy or other structural changes in the brain.
• Blood Tests: To exclude other conditions that can mimic ataxia, such as vitamin deficiencies (e.g., vitamin E or B12), thyroid dysfunction, or infections.
• Electrophysiological Studies: Such as nerve conduction studies and electromyography, to rule out peripheral nerve disorders.
5. Additional Tests: Depending on the initial findings, additional assessments may be needed. For example, lumbar puncture to analyze cerebrospinal fluid (CSF) can help exclude inflammatory or infectious processes affecting the central nervous system.

Spinocerebellar ataxia (SCA) is a progressive, genetic disorder characterized by a loss of coordination and balance, which results from degeneration of the cerebellum and its associated pathways. The diagnosis of SCA typically involves a combination of medical history taking, physical examinations, and diagnostic tests:
1. Medical History Taking:
• Family history: Since SCA is hereditary, a detailed family history of similar symptoms or known genetic disorders is crucial.
• Symptom onset and progression: The age at which symptoms began and how they have progressed over time.
2. Physical Examinations:
• Neurological examination: This includes tests for coordination, gait, speech (dysarthria), eye movements, and reflexes, which help in assessing the degree of cerebellar involvement.
• Motor skills assessment: Evaluation of fine motor movements, balance, and coordination.
3. Diagnostic Tests:
• Genetic testing: The most definitive test for SCA, identifying specific genetic mutations responsible for the condition.
• MRI or CT scans: Imaging studies can reveal changes in the cerebellum and other areas of the brain.
• Electromyography (EMG) and nerve conduction studies: These tests assess the electrical activity of muscles and the speed of nerve signals.
Each patient's results will vary depending on the specific type of SCA and other individual factors.

The specific genetic mutation associated with SCA3, also known as Machado-Joseph Disease (MJD), is an expansion of the CAG trinucleotide repeat in the ATXN3 gene. This gene is located on chromosome 14q32.1. The normal range of CAG repeats in the ATXN3 gene is between 12 to 44, but in individuals with SCA3, the number of repeats is typically expanded to 55 to 86 or more.

Medical Record

Patient ID: 00112233
Date of Birth: January 1, 1970
Date of Visit: May 1, 2024

Chief Complaint:
Progressive difficulty with balance and coordination over the past two years.
Symptoms:
• Unsteady gait
• Frequent stumbling
• Difficulty with fine motor skills, such as buttoning shirts and writing
• Slurred speech
• Occasional double vision
Medical History:
• No known family history of neurological disorders
• Hypertension diagnosed 5 years ago, managed with medication
• No history of significant head trauma or toxin exposure
Physical Examination:
• Abnormal gait characterized by wide base and uncoordinated steps
• Positive Romberg sign
• Dysmetria observed during finger-to-nose test
• Intact sensory examination
• Normal muscle strength but decreased coordination
Diagnostic Tests:
• MRI of the brain: Mild cerebellar atrophy without evidence of stroke or tumor
• Genetic testing: Pending results for mutations associated with spinocerebellar ataxia types 1, 2, 3, 6, and 7
• Complete blood count and metabolic panel: Within normal limits
Differential Diagnosis:
1. Spinocerebellar ataxia
2. Multiple sclerosis
3. Stroke
4. Vitamin B12 deficiency
5. Chronic alcohol abuse

Spinocerebellar ataxia (SCA) is a progressive, degenerative disease characterized by coordination problems and difficulty walking. Consider the case of Mr. Lee, a 55-year-old male who presented with a one-year history of increasing difficulty in maintaining his balance, leading to frequent falls. His family noted that he also had trouble coordinating hand movements and slurred speech. Neurological examination revealed irregular, jerky eye movements and impaired coordination of his limbs, consistent with cerebellar ataxia. Genetic testing confirmed a diagnosis of spinocerebellar ataxia type 3, which is inherited in an autosomal dominant pattern. Mr. Lee was advised on therapeutic exercises and given guidance on safety adaptations for his home to reduce the risk of falls.

Spinocerebellar ataxia (SCA) involves a group of progressive neurodegenerative disorders characterized by a variety of symptoms, primarily affecting coordination and gait. When diagnosing SCA, it's essential to consider other conditions that may present similar symptoms to ensure accurate diagnosis. Here are several diseases that should be considered in the differential diagnosis:
1. Multiple Sclerosis - An autoimmune disease that affects the brain and spinal cord, leading to motor and sensory disturbances similar to SCA.
2. Friedreich's Ataxia - A genetic disorder causing progressive damage to the nervous system, which presents with ataxia and other neurological symptoms similar to SCA.
3. Wilson’s Disease - A genetic disorder resulting in excessive copper accumulation in the body, which can lead to neurological symptoms that mimic SCA.
4. Vitamin E or B12 Deficiency - Deficiencies in these vitamins can cause neurological symptoms, including ataxia.
5. Brain Tumors or Strokes - Mass lesions or ischemic damage in the cerebellum can present with ataxia and need to be ruled out.
6. Other Hereditary Ataxias - Such as ataxia-telangiectasia or autosomal recessive cerebellar ataxias, which may have similar presentations to SCA.