Anaphia

Anaphia, also called tactile anaesthesia, is the total or partial absence of the sense of touch, so that light contact with the skin is not perceived or is perceived only faintly.触觉缺失（anaphia，又称 tactile anaesthesia）指触觉全部或部分丧失，轻触皮肤不能被感知或仅能模糊感知。

It is a symptom and a neurological sign rather than a disease, and its clinical meaning depends on the distribution, the modality affected and the underlying lesion.它属于症状与神经体征而非独立疾病，其临床意义取决于分布、受累感觉模态与潜在病变。

Terminology and classification

• The word anaphia derives from the Greek prefix a-, meaning without, and haphe, meaning touch, and it has been used in medical lexicons since the nineteenth century.该词源自希腊语前缀（a-，无）与（haphe，触），自十九世纪起见于医学辞典。
• Tactile anaesthesia is the common English synonym, and the term anaesthesia in this context refers to loss of sensation rather than to pharmacological anaesthesia.常见英文同义词为（tactile anaesthesia），此处的（anaesthesia）指感觉丧失而非药物麻醉。
• Anaphia must be separated from hypoesthesia, in which touch is reduced but present, and from hyperesthesia, in which sensitivity is increased.触觉缺失须与触觉减退（hypoesthesia，触觉减弱但仍存在）及触觉过敏（hyperesthesia，敏感性增高）相区分。
• Dysesthesia denotes an unpleasant abnormal sensation, whereas analgesia denotes loss of pain sensation and pallanesthesia denotes loss of vibration sense, and each points to a different fibre population.感觉异常（dysesthesia）指不愉快的异常感觉，痛觉丧失（analgesia）指痛觉缺失，振动觉丧失（pallanesthesia）指振动觉缺失，各指向不同的纤维群。
• Astereognosis and tactile agnosia are cortical disorders of recognising objects by touch, and they can occur with relatively preserved elementary touch detection.实体觉缺失与触觉失认属于皮质性触觉物体识别障碍，可在基本触觉检测相对保留时出现。
• In the International Classification of Diseases tenth revision anaesthesia of skin is coded R20.0, and ICD-11 places the same concept in category MB40.3.在国际疾病分类第十版中，皮肤感觉丧失编码为 R20.0，ICD-11 将同一概念置于 MB40.3 类目。
• Because anaphia is a sign, it is usually indexed under the causative disease, such as diabetes, spinal cord injury, stroke or leprosy, rather than as a stand-alone diagnosis.由于触觉缺失是体征，通常归入病因疾病（如糖尿病、脊髓损伤、卒中亚麻风）之下，而非作为独立诊断。

History

• Anaphia appears in nineteenth-century pronouncing medical lexicons, including the 1881 lexicon of Charles Harley Cleaveland, which defined it as loss of the sense of touch.触觉缺失见于十九世纪的医学读音辞典，包括 Charles Harley Cleaveland 1881 年的辞典，其中将其定义为触觉丧失。
• Early neurologists distinguished loss of touch from loss of pain, and this separation laid the foundation for the modern modality-based examination of sensation.早期神经学家将触觉丧失与痛觉丧失区分开来，这一分离为现代按感觉模态进行检查奠定基础。
• Calibrated monofilaments were developed by Semmes and Weinstein in 1960 for the assessment of penetrating brain wounds, and they remain the most widely used bedside tool for touch threshold.Semmes 与 Weinstein 于 1960 年为评估穿通性脑损伤而研制校准单丝，至今仍是触觉阈值最常用的床旁工具。
• Quantitative sensory testing was formalised in the 1990s, allowing thermal and mechanical thresholds to be measured reproducibly in research and in clinical trials.定量感觉测试于二十世纪九十年代形成规范，使温度觉与机械觉阈值能在研究与临床试验中可重复地测量。
• The American Spinal Injury Association published its international standards for neurological classification of spinal cord injury in 1982, and the sensory examination in those standards depends on dermatomal touch and pinprick testing.美国脊髓损伤协会于 1982 年发布脊髓损伤神经学分类国际标准，其中的感觉检查依赖皮节触觉与针刺测试。
• Consensus criteria for diagnosing neuropathic pain, published in 2008 and revised in 2016, incorporated sensory signs such as reduced touch as supporting evidence for a neuropathic mechanism.2008 年发布并于 2016 年修订的神经病理性疼痛诊断共识标准，将触觉减退等感觉体征纳入神经病理性机制的支持证据。
• The International Classification of Diseases eleventh revision, adopted in 2019, introduced a dedicated section for chronic pain and explicitly recognises chronic neuropathic pain as a distinct category.国际疾病分类第十一版于 2019 年通过，新增慢性疼痛专章并明确将慢性神经病理性疼痛列为独立类别。

Epidemiology

• Anaphia itself is not counted in population surveys, and all frequency estimates refer to the causative conditions in which tactile loss occurs.触觉缺失本身不进入人群调查，所有频率估计均针对发生触觉丧失的病因疾病。
• Diabetic peripheral neuropathy affects up to half of people with long-standing diabetes, and loss of protective touch sensation is the major risk factor for foot ulceration.糖尿病周围神经病可累及多达半数病程较长的糖尿病患者，保护性触觉丧失是足部溃疡的主要危险因素。
• Traumatic and non-traumatic spinal cord injury has an estimated global incidence of 40 to 80 cases per million population per year, and nearly all affected patients have some sensory level.创伤性与非创伤性脊髓损伤的全球发病率估计为每年每百万人口 40 至 80 例，几乎所有患者都存在感觉平面。
• Leprosy remains an important cause of sensory loss in endemic countries, with about 200,000 new cases reported each year and peripheral nerve involvement in many of them.麻风在流行国家仍是感觉丧失的重要病因，每年报告约 20 万新发病例，其中许多存在周围神经受累。
• Thalamic and parietal strokes cause hemisensory loss, and pure sensory stroke is a recognised lacunar syndrome that may leave persistent tactile impairment.丘脑与顶叶卒中引起偏身感觉丧失，纯感觉性卒中是一种公认的腔隙综合征，可遗留持续性触觉障碍。
• Age-related decline in tactile sensitivity is common and contributes to falls, burns and difficulty with fine manual tasks in older people.与年龄相关的触觉敏感性下降很常见，促使老年人发生跌倒、烫伤与精细手工作业困难。

Pathophysiology

• Light touch is carried by large myelinated Aβ fibres whose cell bodies lie in the dorsal root ganglia and whose central branches ascend in the dorsal columns.轻触觉由粗大有髓的 Aβ 纤维传导，其胞体位于背根神经节，中枢支在脊髓后柱上行。
• Pain and temperature are carried by thinly myelinated Aδ fibres and unmyelinated C fibres, which is why dissociated sensory loss can spare touch or spare pain.痛觉与温度觉由薄髓的 Aδ 纤维与无髓的 C 纤维传导，因此分离性感觉丧失可保留触觉或保留痛觉。
• A lesion anywhere from the skin to the somatosensory cortex can produce anaphia, including peripheral nerve, plexus, root, spinal cord, brainstem, thalamus and parietal lobe.从皮肤到躯体感觉皮质的任何部位病变都可产生触觉缺失，包括周围神经、神经丛、神经根、脊髓、脑干、丘脑与顶叶。
• Length-dependent peripheral neuropathy begins in the toes and fingers and produces a stocking-and-glove distribution of tactile loss.长度依赖性周围神经病自足趾与手指开始，形成袜套与手套样分布的触觉丧失。
• Compressive lesions such as carpal tunnel syndrome produce a dermatomal or nerve-territory pattern, and the distribution is the main clue to the level of the lesion.腕管综合征等压迫性病变产生皮节或神经支配区分布，分布模式是判断病变水平的主要线索。
• Spinal cord lesions produce a sensory level, and dorsal column damage impairs touch and proprioception while sparing pain and temperature.脊髓病变产生感觉平面，后柱损害影响触觉与本体觉而保留痛温觉。
• Thalamic lesions, especially in the ventral posterolateral nucleus, cause contralateral hemisensory loss that may later be followed by central post-stroke pain.丘脑病变，尤其是腹后外侧核病变，引起对侧偏身感觉丧失，其后可继发中枢性卒中后疼痛。
• Parietal lesions impair higher-order touch processing, producing astereognosis, tactile agnosia and neglect of the contralateral side rather than a simple elevation of threshold.顶叶病变损害高级触觉处理，产生实体觉缺失、触觉失认与对侧忽略，而非单纯的阈值升高。

Clinical features

• Patients may be unaware of tactile loss and report only numbness, clumsiness, burning or the accidental discovery of an injury.患者可能未察觉触觉丧失，仅诉麻木、笨拙、烧灼感或因意外发现伤口而就诊。
• Examination shows absent or reduced appreciation of cotton wool, light finger touch or a 10-gram monofilament in the affected area.检查可见受累区域对棉絮、指尖轻触或 10 克单丝的感知消失或减弱。
• The distribution may be stocking-and-glove, dermatomal, radicular, hemibody or restricted to a single nerve territory, and each pattern has a different differential diagnosis.分布可为袜套手套样、皮节性、神经根性、偏身性或局限于单一神经支配区，各模式对应不同鉴别诊断。
• Loss of protective sensation predisposes to burns, pressure ulcers, unnoticed trauma and Charcot neuroarthropathy, particularly in diabetes.保护性感觉丧失易致烫伤、压疮、未察觉的外伤与 Charcot 神经关节病，糖尿病者尤为突出。
• Patients often describe coexisting positive phenomena such as tingling, pins and needles or electric-shock sensations, which indicate concomitant nerve dysfunction.患者常描述并存的阳性现象，如针刺感、蚁走感或电击样感觉，提示同时存在神经功能障碍。
• In spinal cord injury the sensory level and the preservation of sacral sensation define the completeness of the lesion and guide prognosis.在脊髓损伤中，感觉平面与骶部感觉的保留程度决定病变的完全性并指导预后判断。
• Unilateral anaphia with hemiparesis or aphasia suggests a cortical or thalamic stroke, whereas bilateral distal loss suggests a systemic neuropathy.单侧触觉缺失伴偏瘫或失语提示皮质或丘脑卒中，而双侧远端丧失提示全身性神经病。

Diagnosis

• History should establish onset, progression, symmetry, distribution, associated pain, drug exposure, alcohol use, diabetes and family history of neuropathy.病史应明确起病方式、进展、对称性、分布、伴随疼痛、药物暴露、饮酒、糖尿病与神经病家族史。
• Bedside examination uses cotton wool for light touch, a pin for pain, a 128-hertz tuning fork for vibration and passive movement for proprioception.床旁检查以棉絮测轻触、针测痛觉、128 赫兹音叉测振动觉、被动活动测本体觉。
• The 10-gram Semmes-Weinstein monofilament is the standard test for protective sensation of the foot and predicts ulcer risk in diabetes.10 克 Semmes-Weinstein 单丝是足部保护性感觉的标准检查，可预测糖尿病足溃疡风险。
• Two-point discrimination, stereognosis and graphesthesia test cortical integration and are abnormal in parietal lesions even when elementary touch is preserved.两点辨别、实体觉与图形觉测试皮质整合功能，顶叶病变时即使基本触觉保留也可异常。
• Nerve conduction studies and electromyography localise and characterise large-fibre neuropathy, whereas skin biopsy with intraepidermal nerve fibre density assesses small fibres.神经传导与肌电图用于定位与刻画大纤维神经病，皮肤活检联合表皮内神经纤维密度评估小纤维。
• Magnetic resonance imaging of the spine or brain is indicated when a central lesion is suspected from a sensory level, hemisensory pattern or associated long-tract signs.当感觉平面、偏身模式或伴长束体征提示中枢病变时，应行脊柱或脑磁共振检查。
• Laboratory evaluation includes fasting glucose or glycated haemoglobin, vitamin B12, thyroid function, renal function, serum protein electrophoresis and HIV testing.实验室评估包括空腹血糖或糖化血红蛋白、维生素 B12、甲状腺功能、肾功能、血清蛋白电泳与 HIV 检测。
• The differential includes conversion disorder and malingering, but these should be diagnosed only after organic causes have been excluded by consistent examination and investigations.鉴别诊断包括转换障碍与伪装，但只有在检查与辅助检查一致地排除器质性病因后才能作出此类诊断。

Management

• Treatment is directed at the cause, such as glucose control in diabetes, vitamin replacement in deficiency, nerve decompression and immunosuppression in inflammatory neuropathy.治疗针对病因，如糖尿病控制血糖、缺乏者补充维生素、神经受压者减压、炎症性神经病者免疫抑制。
• Leprosy requires multidrug therapy, and prompt treatment prevents further nerve damage and deformity.麻风需多药联合治疗，及时治疗可防止进一步神经损害与畸形。
• Neuropathic pain, when present, is treated with gabapentin, pregabalin, duloxetine or amitriptyline, and combination therapy is sometimes required.伴有神经病理性疼痛时，使用加巴喷丁（gabapentin）、普瑞巴林（pregabalin）、度洛西汀（duloxetine）或阿米替林（amitriptyline），有时需联合用药。^[1]
• Foot care is central in distal sensory loss, with daily inspection, well-fitting protective footwear and avoidance of walking barefoot.远端感觉丧失时足部护理至关重要，包括每日检查、合脚的防护鞋与避免赤足行走。
• Burn prevention, padding of sharp furniture and education of families are important for patients with widespread tactile loss.对广泛触觉丧失患者，预防烫伤、对尖锐家具加装护垫及家属教育十分重要。
• Sensory re-education and occupational therapy can improve function after peripheral nerve injury and after stroke, although recovery of threshold is often incomplete.感觉再教育与作业治疗可改善周围神经损伤及卒中后的功能，但阈值恢复常不完全。
• There is no proven intervention that restores lost touch sensation, and most treatments aim to prevent complications and to manage pain.尚无证实能恢复丧失触觉的干预，多数治疗旨在预防并发症与管理疼痛。
• Prognosis depends on the cause, with reversible causes such as compression and vitamin deficiency offering better recovery than degenerative or traumatic lesions.预后取决于病因，压迫与维生素缺乏等可逆病因的恢复优于变性与创伤性病变。

Research and controversies

• Restoration of touch is an active field, including nerve conduits, decellularised grafts, sensory prostheses and brain-computer interfaces.触觉重建是活跃领域，包括神经导管、脱细胞移植物、感觉假体与脑机接口。
• Quantitative sensory testing lacks a single agreed protocol, and reference values vary between laboratories, which limits comparison across studies.定量感觉测试缺乏统一方案，各实验室参考值不同，限制了研究间比较。^[2]
• Small-fibre neuropathy is under-recognised because routine nerve conduction studies are normal, and skin biopsy availability remains limited.小纤维神经病因常规神经传导正常而被低估，皮肤活检的可及性仍有限。
• Whether cortical remapping after sensory loss can be harnessed for rehabilitation is unresolved, and trials of sensory training have produced mixed results.感觉丧失后皮质重映射能否用于康复尚未明确，感觉训练试验结果不一。
• Digital monofilaments and automated von Frey devices are being developed for telemedicine, but validation against the standard examination is incomplete.数字单丝与自动 von Frey 装置正被开发用于远程医疗，但相对标准检查的验证尚不完整。
• The boundary between anaphia and cortical tactile agnosia remains imprecise, and better lesion-symptom mapping is needed to separate perceptual from recognition deficits.触觉缺失与皮质性触觉失认之间的界限仍不精确，需更好的病变症状映射以区分感知与识别缺陷。