脊髓皮质下变性症是一种严重的、逐渐加剧的神经退行性疾病，通常由维生素B12缺乏引起。该病影响脊髓，特别是后柱和侧柱，导致神经退行。这种对这些区域的损伤会引起一系列神经系统症状，包括虚弱、异常感觉和协调问题。

脊髓皮质下变性症通常具有以下临床特征：
1. 感觉性共济失调：由于深度感觉丧失，难以控制运动，尤其是在黑暗中或闭眼时，难以协调肌肉动作。
2. 运动障碍：肌肉弱或肌肉张力改变，严重情况下可能导致瘫痪。
3. 自主神经功能障碍：通常是自主的身体功能出现问题，如膀胱控制。
4. 神经精神症状：由于神经系统的参与，情绪变化、认知受损，有时还可能出现精神症状。

脊髓皮质下变性症的类型通常指的是根据脊髓中受影响的部分不同，神经功能缺失的不同模式。这些类型通常基于脊髓中特定传导束的退行性变分为以下几类：
• 后柱退行：导致本体感觉（身体位置感）和振动感觉丧失。
• 侧脊髓皮质束退行：导致虚弱、肌肉张力增加和反射亢进。

SCD的主要原因是维生素B12缺乏，可能由饮食不足（在素食者中常见）、吸收不良如恶性贫血、胃肠道手术或影响B12代谢的遗传因素引起。

为了鉴别诊断脊髓的亚急性联合变性，需要系统地收集患者信息和测试结果。具体包括：
1. 症状：患者通常表现为虚弱、麻木、刺痛和协调能力受损，特别是下肢。这些症状可能会进一步影响到上肢。
2. 病史：重要的方面包括饮食史（以评估维生素B12缺乏的可能性）、胃肠道手术史（如胃旁路手术可能影响B12吸收）、酒精滥用以及任何可能影响营养吸收的慢性胃肠道疾病。还应考虑自身免疫疾病史或使用干扰维生素B12吸收的药物。
3. 体格检查：神经系统检查，检查感觉、力量和反射的异常，特别是寻找脊髓病变的迹象。其他检查可能包括评估精神状态变化以及检查贫血或黄疸的迹象，这些可能伴随维生素B12缺乏。
4. 诊断测试：
• 血液测试：测量血清维生素B12水平至关重要。完全血细胞计数（CBC）可能显示大细胞性贫血。甲基丙二酸和同型半胱氨酸水平在维生素B12缺乏时可能升高。
• 脊髓MRI：重要的是可视化脊髓受累程度，并与多发性硬化症或脊髓压迫等其他潜在的脊髓病变鉴别。
• 附加测试：席林试验评估B12吸收、内因子抗体试验和胃壁细胞抗体试验，以识别恶性贫血。
5. 鉴别诊断：重要的是将脊髓的亚急性联合变性与其他脊髓病变和神经病变区分开。这包括排除多发性硬化症、铜缺乏症、HIV相关脊髓病变和压迫性脊髓病等病状。

通过综合这些数据点，临床医生可以有效地从其他类似的神经系统疾病中鉴别出脊髓的亚急性联合变性。

诊断脊髓皮质联合变性（SCD）主要与维生素B12缺乏有关，通常见于恶性贫血等状况。以下是通过病史、体检和诊断测试的具体诊断方法：

1. 病史：患者可能报告与B12缺乏相符的症状，包括：
• 进展性虚弱
• 四肢麻木和刺痛感
• 步态不稳和平衡问题
• 记忆障碍和情绪变化
同时，询问患者的饮食习惯尤为重要，特别是那些可能不摄入足够B12的素食者或严格素食者，以及有胃肠手术或疾病史可能影响B12吸收的情况。

2. 体检：关键发现可能包括：
• 下肢的振动感和位置感减退
• 肌肉无力和萎缩
• 反射异常，包括反射亢进或Babinski征
• 步态异常反映出共济失调或痉挛

3. 诊断测试：
• 血液测试：显示B12水平低，甲基丙二酸（MMA）和同型半胱氨酸水平升高。
• 脊柱MRI：T2加权图像上脊髓后索可能显示高信号白质变化。
• 电生理研究：可以评估神经传导，特别是在描绘周围神经受累程度时非常有用。

治疗主要包括B12补充，如果早期开始治疗，可以显著改善临床症状。

病例记录示例

患者信息：
• 姓名： [匿名]
• 年龄： 52岁
• 性别： 男性

症状：
• 手脚逐渐出现麻木和刺痛感
• 腿部无力，行走困难
• 触觉障碍
• 认知损害，如记忆力下降
病史：
• 恶性贫血病史
• 10年前进行了胃部部分切除手术
• 无糖尿病或酒精滥用史
• 素食饮食
体检：
• 下肢振动感和位置感减退
• 双膝反射亢进
• 罗姆伯格征阳性
• 心理状态检查中注意到轻度认知障碍
诊断测试：
• 血液测试：
• 维生素B12水平低
• 甲基丙二酸和同型半胱氨酸水平升高
• 脊柱MRI检查：
• 颈椎和胸椎脊髓后索区出现高信号
• 神经传导研究：
• 下肢感觉潜伏期延长
鉴别诊断：
• 由于维生素B12缺乏引起的脊髓联合变性
• 多发性硬化症
• 脊髓肿瘤
• 其他原因的脊髓病变，如颈椎病变

脊髓亚急性联合变性通常出现在长期维生素B12缺乏的患者中，常因吸收不良问题如恶性贫血而发病。一个典型的病例可能涉及一名55岁女性，她抱怨手脚逐渐出现麻木和刺痛感，行走困难，并感到总体虚弱。神经系统检查可能显示本体感觉和振动感觉减退，脊柱MRI可能显示后索信号强度异常。实验室检查可能确认维生素B12水平低，甲基丙二酸和同型半胱氨酸水平可能升高。

在对脊髓皮质亚急性联合变性进行鉴别诊断时，应考虑几种其他疾病，因为它们的症状有重叠。这些包括：
1. 维生素B12缺乏 - 这是脊髓皮质亚急性联合变性的主要原因，因此评估维生素B12水平至关重要。
2. 铜缺乏 - 可以模仿维生素B12缺乏的神经系统症状。
3. 多发性硬化症 - 可以引起类似的神经系统症状，如虚弱和感觉变化。
4. HIV相关脊髓病变 - 也会导致类似的脊髓退化和神经系统症状。
5. HTLV-1相关脊髓病变 - 另一种病毒引起的脊髓症状，需要排除。
6. 颈椎病性脊髓病 - 由颈椎骨关节炎引起的脊髓压迫退化，呈现类似症状。
7. 神经梅毒 - 可以引起脊髓的渐进性退化，表现出类似的神经系统缺损。
这些条件可能表现出与脊髓皮质亚急性联合变性相似的症状，如虚弱、感觉变化和步态障碍，使得在鉴别诊断中考虑它们很重要。

维生素B12缺乏性神经病和脊髓亚急性联合变性（SCD）是相关但不完全相同的疾病。
• 维生素B12缺乏性神经病：这一术语通常指因缺乏维生素B12引起的神经损伤。症状可能包括麻木、刺痛、无力和反射消失，主要影响外周神经。
• 脊髓亚急性联合变性（SCD）：这是维生素B12缺乏的一种特定且严重的形式，影响脊髓。SCD导致背柱和侧皮质脊髓束的变性，导致症状如无力、感觉性共济失调和痉挛。
总之，维生素B12缺乏性神经病可以包括由于维生素B12缺乏引起的各种类型的神经损伤，而SCD则是涉及脊髓的特定表现形式。

Subacute combined degeneration of the spinal cord (SCD) is a serious, progressive neurodegenerative disorder that most commonly results from a deficiency of vitamin B12. It affects the spinal cord, particularly the posterior and lateral columns, leading to the degeneration of nerves. The damage to these areas can cause a combination of neurological symptoms including weakness, abnormal sensations, and problems with coordination.

SCD is typically characterized by the following clinical features:
1. Sensory ataxia: Difficulty controlling movements due to loss of deep sensation, making it hard to coordinate muscle movements, especially in the dark or with closed eyes.
2. Motor disturbances: Weakness or changes in muscle tone, and in severe cases, paralysis.
3. Autonomic dysfunction: Problems with bodily functions that are usually involuntary, such as bladder control.
4. Neuropsychiatric symptoms: Changes in mood, cognitive impairment, and in some cases, psychotic symptoms due to the involvement of the nervous system.

The types of SCD generally refer to the different patterns of neurologic deficits depending on which parts of the spinal cord are most affected. These are typically categorized based on the degeneration of specific tracts within the spinal cord:
• Posterior column degeneration: Leads to loss of proprioception (sense of body position) and vibratory sensation.
• Lateral corticospinal tract degeneration: Causes weakness, increased muscle tone, and hyperreflexia.

The primary cause of SCD is vitamin B12 deficiency, which can result from dietary insufficiency (common in vegetarians), malabsorption conditions such as pernicious anemia, gastrointestinal surgeries, or genetic factors affecting B12 metabolism.

To differentially diagnose subacute combined degeneration of the spinal cord, a detailed and systematic approach is required to gather patient information and test results. Here's a breakdown:
1. Symptoms: Patients typically present with symptoms such as weakness, numbness, tingling, and impaired coordination, particularly in the lower limbs. These symptoms might progress to affect the upper limbs as well.
2. Medical History: Key aspects include dietary history to assess for potential vitamin B12 deficiency, history of gastrointestinal surgeries (like gastric bypass which may affect B12 absorption), alcohol abuse, and any chronic conditions affecting the gastrointestinal tract which might impair nutrient absorption. A history of autoimmune disorders or use of medications that interfere with vitamin B12 absorption should also be considered.
3. Physical Examinations: Neurological examination to check for abnormalities in sensation, strength, and reflexes, particularly looking for signs of myelopathy. Additional examination might include assessing mental status changes and evaluating for signs of anemia or jaundice, which can accompany vitamin B12 deficiency.
4. Diagnostic Tests:
• Blood Tests: Measurement of serum vitamin B12 levels is crucial. Complete blood count (CBC) may show macrocytic anemia. Methylmalonic acid and homocysteine levels can be elevated in vitamin B12 deficiency.
• MRI of the Spinal Cord: This is important to visualize the extent of spinal cord involvement and to differentiate from other potential causes of myelopathy like multiple sclerosis or spinal cord compression.
• Additional Testing: Schilling test to evaluate B12 absorption, intrinsic factor antibody test, and gastric parietal cell antibody test to identify pernicious anemia.
5. Differential Diagnosis: It's important to differentiate subacute combined degeneration from other causes of myelopathy and neuropathy. This includes ruling out conditions like multiple sclerosis, copper deficiency, HIV-associated myelopathy, and compressive myelopathies.

By integrating these data points, clinicians can effectively differentiate subacute combined degeneration of the spinal cord from other similar neurological disorders.

Subacute combined degeneration (SCD) of the spinal cord is primarily associated with vitamin B12 deficiency, typically seen in conditions such as pernicious anemia. Here's how it is diagnosed through medical history, physical examinations, and diagnostic tests:

1. Medical History: Patients might report symptoms consistent with B12 deficiency which include:
• Progressive weakness
• Numbness and tingling in the extremities
• Unsteady gait and balance issues
• Memory disturbances and mood changes
It's also important to inquire about dietary habits, especially in vegan or vegetarian individuals who might not ingest enough B12, as well as a history of gastrointestinal surgeries or diseases that might affect B12 absorption.

2. Physical Examination: Key findings may include:
• Diminished vibration and position sense, particularly in the lower extremities
• Muscle weakness and atrophy
• Abnormal reflexes, including hyperreflexia or Babinski sign
• Gait abnormalities reflecting ataxia or spasticity

3. Diagnostic Tests:
• Blood Tests: Show low levels of B12, elevated methylmalonic acid (MMA), and homocysteine levels.
• MRI of the Spine: May reveal hyperintense white matter signal changes in the posterior columns of the spinal cord on T2-weighted images.
• Electrophysiological Studies: Can assess nerve conduction and are particularly useful in delineating the extent of peripheral nerve involvement.

Management primarily involves B12 supplementation, which can lead to significant clinical improvement, especially if started early.

Medical Record Example

Patient Information:
• Name: [Anonymous]
• Age: 52 years
• Gender: Male

Symptoms:
• Gradual numbness and tingling in hands and feet
• Weakness in legs, difficulty walking
• Disturbed sense of touch
• Cognitive impairments like memory loss
Medical History:
• History of pernicious anemia
• Gastrointestinal surgery (partial gastrectomy) 10 years ago
• No history of diabetes or alcohol abuse
• Vegetarian diet
Physical Examination:
• Decreased vibration and position sense in lower limbs
• Hyperreflexia in both knees
• Positive Romberg sign
• Mild cognitive impairment noted during mental status examination
Diagnostic Tests:
• Blood Tests:
• Low vitamin B12 levels
• Elevated methylmalonic acid and homocysteine levels
• MRI of the Spine:
• Hyperintensities in the posterior columns of the cervical and thoracic spinal cord
• Nerve Conduction Studies:
• Delayed sensory potentials, especially in the lower limbs
Differential Diagnosis:
• Subacute combined degeneration of the spinal cord due to vitamin B12 deficiency
• Multiple sclerosis
• Spinal cord tumor
• Other causes of myelopathy like cervical spondylosis

Subacute combined degeneration of the spinal cord typically presents in patients with a history of prolonged vitamin B12 deficiency, often due to malabsorption issues such as pernicious anemia. A typical case might involve a 55-year-old female complaining of progressive numbness and tingling in her hands and feet, combined with difficulty walking and a general feeling of weakness. Neurological examination may reveal diminished proprioception and vibratory sense, and an MRI of the spine could show abnormal signal intensity in the posterior columns. Laboratory tests would likely confirm low levels of vitamin B12, and possibly elevated methylmalonic acid and homocysteine levels.

In the differential diagnosis of subacute combined degeneration of the spinal cord, several other conditions should be considered due to overlapping symptoms. These include:
1. Vitamin B12 deficiency - This is the primary cause of subacute combined degeneration, so assessing vitamin B12 levels is crucial.
2. Copper deficiency - Can mimic the neurological symptoms of vitamin B12 deficiency.
3. Multiple sclerosis - Can cause similar neurological symptoms, such as weakness and sensory changes.
4. HIV-associated myelopathy - Also leads to similar spinal cord degeneration and neurological symptoms.
5. HTLV-1 associated myelopathy - Another viral cause of spinal cord symptoms that needs to be ruled out.
6. Cervical spondylotic myelopathy - Degeneration due to spinal cord compression from cervical spine osteoarthritis, presenting with similar symptoms.
7. Neurosyphilis - Can cause progressive degeneration of the spinal cord, presenting with similar neurological deficits.

These conditions can present with symptoms similar to subacute combined degeneration of the spinal cord, such as weakness, sensory changes, and gait disturbances, making them important to consider in the differential diagnosis.

Vitamin B12 deficiency neuropathy and Subacute Combined Degeneration (SCD) of the spinal cord are related but not the same condition.
• Vitamin B12 deficiency neuropathy: This term generally refers to the nerve damage that occurs due to a lack of Vitamin B12. Symptoms may include numbness, tingling, weakness, and loss of reflexes, primarily affecting the peripheral nerves.
• Subacute Combined Degeneration (SCD) of the spinal cord: This is a specific and severe form of Vitamin B12 deficiency that affects the spinal cord. SCD results in degeneration of the dorsal columns and the lateral corticospinal tracts, leading to symptoms such as weakness, sensory ataxia, and spasticity.

In summary, Vitamin B12 deficiency neuropathy can encompass various types of nerve damage due to Vitamin B12 deficiency, while SCD is a specific manifestation involving the spinal cord.