Numbness, Tingling, and Sensory Loss¶
Chapter 27 | Part 2: Cardinal Manifestations and Presentation of Diseases
KEY CLINICAL POINTS¶
- Sensory symptoms are classified as positive (tingling, burning, pain) or negative (numbness, loss of sensation) - positive symptoms arise from ectopic impulse generation while negative symptoms indicate sensory fiber loss
- At least 50% of afferent axons must be lost before clinical examination reveals a sensory deficit; subclinical dysfunction may be detected by nerve conduction studies
- Anatomic localization is critical: length-dependent polyneuropathies cause stocking-glove distribution; dermatomal patterns indicate root lesions; hemisensory loss suggests thalamic or cortical pathology
- The spinothalamic tract (pain, temperature) crosses in the spinal cord and ascends contralaterally; the posterior column-lemniscal system (proprioception, vibration) ascends ipsilaterally before crossing in the medulla
- Dissociated sensory loss (selective impairment of pain/temperature with preserved proprioception) indicates spinothalamic tract or central cord lesions such as syringomyelia
1. DEFINITION & OVERVIEW¶
Somatic sensation involves continuous monitoring of the body's internal and external environment, most of which occurs below conscious awareness. Disordered sensation, particularly when painful, commands attention and is a common presenting complaint. Understanding the nature, distribution, and characteristics of sensory abnormalities is essential for accurate anatomic localization and diagnosis. Pain as a primary symptom is addressed separately (Chapter 14).
1.1 Positive vs Negative Symptoms¶
Sensory abnormalities are categorized into two fundamental types: Positive Symptoms: Result from trains of impulses generated at sites of lowered threshold or heightened excitability along sensory pathways. Include tingling (pins and needles), itch, pricking, bandlike sensations, lancinations (lightning-like shooting), aching, knifelike, twisting, drawing, pulling, tightening, burning, searing, electrical, or raw feelings. These are often painful and do not necessarily indicate sensory deficit on examination. Negative Symptoms: Represent loss of sensory function, experienced as numbness with diminished or absent feeling. Associated with abnormal findings on sensory examination. At least 50% of afferent axons innervating a site must be lost or nonfunctional before clinical deficit is demonstrable. Slow progressive loss may be unnoticed by patient; rapid loss produces both positive and negative phenomena.
2. TERMINOLOGY¶
Precise terminology is essential for accurate communication about sensory phenomena. Terms are divided into those describing symptoms (patient-reported) and signs (examination findings).
2.1 Symptom Terminology¶
Paresthesias: Tingling or pins-and-needles sensations; may include various abnormal sensations except pain; implies spontaneous perception without stimulus. Dysesthesias: Broad term encompassing all types of abnormal sensations, including painful ones, whether spontaneous or stimulus-evoked.
2.2 Examination Finding Terminology¶
Hypesthesia/Hypoesthesia: Reduced cutaneous sensation to specific stimuli (pressure, light touch, thermal) Anesthesia: Complete absence of skin sensation to touch, pressure, thermal stimuli, and pinprick Hypalgesia: Reduced pain perception (nociception) Analgesia: Absent pain perception Hyperesthesia: Pain or increased sensitivity in response to touch Allodynia: Nonpainful stimulus perceived as painful (e.g., vibrating tuning fork causing pain) Hyperalgesia: Severe pain from mildly noxious stimulus Hyperpathia: Encompasses hyperesthesia, allodynia, and hyperalgesia; characterized by increased threshold with delayed but excessively painful perception once felt
2.3 Proprioceptive Dysfunction Terminology¶
Sensory Ataxia: Manifestations of deep sensation disorders affecting proprioception from muscle spindles, tendons, and joints. Includes: - Imbalance (worse with eyes closed or in dark) - Clumsiness of precision movements - Unsteadiness of gait Associated Examination Findings: - Reduced or absent joint position sense - Reduced or absent vibration sense - Absent deep tendon reflexes in affected limbs - Positive Romberg sign (marked swaying or toppling when standing with feet together and eyes closed) Pseudoathetosis: Continuous involuntary movements of outstretched hands and fingers (worse with eyes closed) in severe deafferentation states
3. ANATOMY OF SENSATION¶
Understanding the dual ascending sensory pathways is fundamental to localizing lesions causing sensory disturbance.
Table 27-1: Testing Primary Sensation¶
| Sense | Test Device | Endings Activated | Fiber Size | Central Pathway |
|---|---|---|---|---|
| Pain | Pinprick | Cutaneous nociceptors | Small | SpTh, also D |
| Temperature (heat) | Warm metal object | Cutaneous thermoreceptors for hot | Small | SpTh |
| Temperature (cold) | Cold metal object | Cutaneous thermoreceptors for cold | Small | SpTh |
| Touch | Cotton wisp, fine brush | Cutaneous mechanoreceptors, also naked endings | Large and small | Lem, also D and SpTh |
| Vibration | Tuning fork, 128 Hz | Mechanoreceptors, especially pacinian corpuscles | Large | Lem, also D |
| Joint position | Passive movement of specific joints | Joint capsule and tendon endings, muscle spindles | Large | Lem, also D |
3.1 Cutaneous Receptors¶
Naked Nerve Endings: - Nociceptors: Respond to tissue-damaging stimuli - Thermoreceptors: Respond to non-injurious thermal stimuli Encapsulated Terminals: - Multiple mechanoreceptor types - Activated by physical deformation of skin or muscle stretch - Each receptor type has specific sensitivities, receptive field characteristics, and adaptational qualities
3.2 Spinothalamic Pathway (Anterolateral System)¶
Fibers: Small myelinated and unmyelinated fibers Modalities: Pain, itch, temperature, and touch Course: 1. Afferent fibers enter dorsal horn via dorsal roots (cell bodies in dorsal root ganglia) 2. Synapse in dorsal horn 3. Cross to contralateral side in spinal cord 4. Ascend in anterior and lateral columns 5. Through brainstem to ventral posterolateral (VPL) nucleus of thalamus 6. Project to postcentral gyrus of parietal cortex and other cortical areas Clinical Implication: Lesions produce contralateral sensory loss below the level of the lesion
3.3 Posterior Column-Medial Lemniscal Pathway¶
Fibers: Large myelinated fibers Modalities: Tactile sensation, position sense, kinesthesia Course: 1. Afferent fibers enter dorsal horn via dorsal roots 2. Ascend ipsilaterally in posterior and posterolateral columns 3. First synapse in gracile or cuneate nucleus of lower medulla 4. Second-order neurons decussate and ascend in medial lemniscus 5. Through tegmentum of pons and midbrain to VPL nucleus of thalamus 6. Third-order neurons project to parietal cortex Clinical Implication: Complete posterior column lesions may cause surprisingly little sensory deficit because touch and pressure also travel in diffusely distributed anterolateral fibers
3.4 Trigeminal System¶
Sensations from face and head are conveyed through the trigeminal system in an analogous fashion to spinal sensory pathways.
4. CLINICAL EXAMINATION OF SENSATION¶
The sensory examination depends on patient responses, which complicates interpretation. Systematic evaluation involves testing primary sensation, cortical sensation, and comparing findings between body sides.
4.1 General Principles¶
In Stuporous Patients: Observe briskness of withdrawal to pinch or noxious stimuli; compare responses between body sides. In Uncooperative Patients: Proprioceptive function may be assessed by observing movements requiring balance and precision. In Patients with Sensory Complaints: - Begin testing in center of affected region - Proceed radially until sensation normalizes - Define distribution and compare to root and peripheral nerve territories - Consider psychological causes if findings don't fit anatomic localization or show gross inconsistencies In Patients without Neurologic Complaints: Brief screening with pinprick, touch, and vibration testing in hands and feet, plus stance/gait evaluation including Romberg maneuver
4.2 Primary Sensation Testing¶
Pain: Use clean pin (discard after use); patient closes eyes and focuses on pricking/unpleasant quality, not pressure; map hypalgesia from most affected area radially outward. Temperature: Ideally use small containers with water at desired temperatures; alternatives include metal tuning fork at room temperature (cold) or warmed under water (heat). Test both cold and warm separately as different receptors are involved. Touch: Use wisp of cotton with minimal pressure; avoid hairy skin due to profuse hair follicle sensory endings; patient responds immediately when stimulus is perceived, indicating location. Joint Position: Test with eyes closed at distal interphalangeal joints of great toe and fingers; hold digit by sides distal to joint being tested; move passively while stabilizing proximal joints; if errors occur, test more proximal joints. Proximal shoulder proprioception: bring index fingers together with arms extended and eyes closed (normal error ≤ 1 cm). Vibration: Use 128 Hz tuning fork over bony prominences; begin distally (dorsal surface of distal phalanx of big toe, malleoli of ankles; dorsally at distal finger phalanx); if abnormal, test more proximal sites; compare thresholds with examiner's own perception.
4.3 Cortical Sensation Testing¶
Abnormalities with normal primary sensation in an alert, cooperative patient indicate parietal cortex or thalamocortical lesion. Always compare analogous sites bilaterally. Two-Point Discrimination: Use calipers set 2 mm to several cm apart, applied simultaneously; normal fingertip threshold approximately 3 mm. Touch Localization: Light pressure with fingertip or cotton wisp; patient (eyes closed) identifies site of touch. Bilateral Simultaneous Stimulation: Touch analogous sites (e.g., both hands) simultaneously; extinction/neglect is consistent failure to perceive touch on one side. Graphesthesia: Capacity to recognize letters or numbers drawn on palm with eyes closed; inability = agraphesthesia; compare sides. Stereognosis: Identify common objects (keys, paper clips, coins) by palpation; should distinguish dime from penny, nickel from quarter; test one hand at a time; inability in one hand with preserved ability in other = astereognosis of abnormal hand.
4.4 Quantitative Sensory Testing¶
Commercially available devices allow threshold testing for touch, vibration, and thermal sensation. Particularly useful for serial evaluation in clinical trials.
4.5 Electrodiagnostic Studies and Nerve Biopsy¶
Nerve conduction studies and nerve biopsy evaluate peripheral nervous system but do not assess: - Cutaneous receptors and free nerve endings - Unmyelinated or thinly myelinated nerve fibers Skin biopsy can evaluate these structures in dermis and epidermis.
5. LOCALIZATION OF SENSORY ABNORMALITIES¶
Sensory symptoms and signs can arise from lesions at any level from parietal cortex to peripheral receptor. The distribution, configuration, symmetry, quality, and severity of abnormalities are key to anatomic localization.
Localization of Sensory Abnormalities by Distribution Pattern¶
| Pattern | Localization | Key Features |
|---|---|---|
| Stocking-glove, length-dependent, symmetric | Polyneuropathy | Begins toes fi ascends; fingertips involved when reaches knees |
| Single nerve territory | Mononeuropathy | Discrete boundaries matching nerve distribution |
| Multiple discrete nerve territories | Multiple mononeuropathy | May become confluent simulating polyneuropathy |
| Dermatomal with radicular pain | Root lesion | May be minimal due to overlap; deep aching along nerve trunk |
| Asymmetric, non-length-dependent, all modalities | Sensory neuronopathy | Paraneoplastic, Sjögren's, idiopathic |
| Sensory level on trunk, UMN signs | Spinal cord | Dissociated loss suggests spinothalamic or central cord lesion |
| Pattern | Localization | Key Features |
|---|---|---|
| Crossed face-body pattern | Lateral medulla | Ipsilateral face, contralateral body |
| Hemisensory head-to-toe | Thalamus or anterior parietal cortex | Abrupt onset suggests lacunar stroke |
| Hemineglect, abnormal cortical testing, intact primary | Parietal cortex | Two-point discrimination, graphesthesia abnormal |
| Non-anatomic, variable, midline splitting | Consider psychogenic | Requires positive suggestive findings |
5.1 Peripheral Nerve and Root Lesions¶
Dysesthesias without Examination Findings: May be systemic (hyperventilation, acetazolamide) or early polyneuropathy/myelopathy (B12 deficiency). Sometimes no definable basis exists. Dysesthesias matching a specific nerve distribution indicate lesion at that site (e.g., fifth digit and adjacent half of fourth finger = ulnar nerve, usually at elbow). Focal Nerve Lesions: Sensory abnormalities are readily mapped with discrete boundaries. Root (Radicular) Lesions: Frequently accompanied by deep, aching pain along the related nerve trunk. Sciatica (radicular pain to sciatic nerve) is common with L5 or S1 root compression from ruptured disk. Single root lesions may have minimal sensory deficit due to extensive overlap of adjacent root territories. Isolated Mononeuropathies: May cause symptoms beyond the territory supplied but examination abnormalities are confined to expected anatomic boundaries. Multiple Mononeuropathies: Symptoms and signs in discrete territories of different nerves; may simulate polyneuropathy when confluent.
5.2 Polyneuropathies¶
General Pattern: - Length-dependent (nerve length-dependent) - Graded, distal, symmetric distribution - "Stocking-glove" pattern - Dysesthesias and numbness begin in toes, ascend symmetrically - When dysesthesias reach knees, usually also appear in fingertips Small-Fiber Polyneuropathies: - Burning, painful dysesthesias - Reduced pinprick and thermal sensation - Preserved proprioception, motor function, deep tendon reflexes - Variable touch involvement - When touch spared: dissociated sensory loss Large-Fiber Polyneuropathies: - Vibration and position sense deficits - Imbalance - Absent tendon reflexes - Variable motor dysfunction - Preserved cutaneous sensation - Dysesthesias (if present): tingling or bandlike quality
5.3 Sensory Neuronopathy (Ganglionopathy)¶
Characteristics: - Widespread but asymmetric sensory loss - Non-length-dependent (proximal or distal) - May affect arms, legs, or both - Pain and numbness progress to sensory ataxia - All sensory modalities impaired over time Etiology: Usually paraneoplastic, idiopathic, or autoimmune (especially Sjögren's syndrome)
5.4 Spinal Cord Lesions¶
Complete Transection: All sensation lost below lesion level; bladder, bowel, and motor function also lost. Brown-Séquard Syndrome (Lateral Hemisection): - Contralateral: Absent pain and temperature sensation - Ipsilateral: Loss of proprioception and motor power - Ipsilateral pain or hyperesthesia may also occur Bilateral Foot Numbness/Paresthesias from Cord Lesion: Likely when upper sensory level extends to trunk; cervical or brainstem lesion if all extremities affected (unless peripheral neuropathy). Upper motor neuron signs support central lesion; hyperesthetic band may suggest level. Dissociated Sensory Loss in Cord: - Reflects spinothalamic tract involvement - May be unilateral with upper trunk level - Bilateral with central cord lesions (e.g., syringomyelia) - Impaired pinprick and temperature with preserved light touch, position, vibration Posterior Column Dysfunction: - Bandlike sensation around trunk - Tight pressure feeling in limbs - Lhermitte's sign: Electric shock sensation radiating down back and into legs with neck flexion (seen in multiple sclerosis, cervical spondylosis, post-cervical irradiation)
5.5 Brainstem Lesions¶
Crossed Sensory Pattern: One side of face affected with opposite side of body = lateral medulla lesion. Small lesion damages both: - Ipsilateral descending trigeminal tract and nucleus - Ascending spinothalamic fibers for contralateral arm, leg, and hemitorso Pons/Midbrain Tegmentum Lesions: Lemniscal and spinothalamic tracts merge here; lesion causes contralateral pansensory loss.
5.6 Thalamic Lesions¶
Hemisensory Disturbance: Tingling numbness from head to foot; may also arise from anterior parietal region. Abrupt onset suggests small stroke (lacunar infarction). Déjerine-Roussy Syndrome (Thalamic Pain Syndrome): - Occurs with VPL nucleus or adjacent white matter lesions - Severe, persistent, unrelenting unilateral pain - Often described in dramatic terms
5.7 Cortical Lesions¶
Parietal Lobe (Cortex or Subjacent White Matter): - Contralateral hemineglect and hemi-inattention - Tendency not to use affected hand and arm - Abnormal cortical sensory testing (two-point discrimination, graphesthesia) - Primary sensation usually intact Anterior Parietal Infarction: - Pseudothalamic syndrome with contralateral primary sensory loss head to toe - May cause dysesthesias, numbness, or rarely painful state
5.8 Focal Sensory Seizures¶
Etiology: Lesions in postcentral or precentral gyrus area Symptoms: - Principal symptom: tingling - Additional sensations: rushing feeling, warmth, sense of movement without motion - Typically unilateral - Commonly begin in arm/hand, face, or foot Jacksonian March: Symptom spread reflecting cortical representation of body parts Duration: Seconds to over an hour; may progress to focal motor features, generalization with loss of consciousness and tonic-clonic jerking
5.9 Psychogenic Sensory Symptoms¶
Suggestive Features (diagnosis should NOT be by exclusion): - Anatomic boundaries difficult to explain neurologically (circumferential at groin, shoulder, or around specific joint) - Variable nature and intensity of disturbances - Midline splitting of impaired vibration, pinprick, or light touch - Variability or poor reproducibility of deficits - Normal performance of tasks requiring sensory input that appears abnormal on formal testing (e.g., good finger-to-nose with eyes closed despite apparent position sense loss) - Confusion of affected side when limbs placed in unusual positions (e.g., crossed behind back) Caution: Do not dismiss unusual sensory complaints as psychogenic simply because they are atypical
6. DIFFERENTIAL DIAGNOSIS¶
The differential diagnosis of sensory disturbance is determined by the anatomic localization suggested by the clinical pattern.
6.1 Polyneuropathy Causes¶
Small-Fiber Predominant: Diabetes mellitus, amyloidosis, HIV, Fabry disease, hereditary sensory neuropathies, idiopathic Large-Fiber Predominant: Vitamin B12 deficiency, chronic inflammatory demyelinating polyneuropathy (CIDP), Friedreich ataxia, paraproteinemic neuropathies
6.2 Sensory Neuronopathy Causes¶
- Paraneoplastic (anti-Hu antibodies, small cell lung cancer) - Sjögren's syndrome - Idiopathic
- Cisplatin and other chemotherapy - Vitamin B6 toxicity
6.3 Myelopathy Causes¶
- Multiple sclerosis - Vitamin B12 deficiency (subacute combined degeneration) - Cervical spondylotic myelopathy - Spinal cord tumors - Syringomyelia - Transverse myelitis - Radiation myelopathy
6.4 Central Causes¶
- Stroke (thalamic, parietal) - Multiple sclerosis - Tumors - Focal seizures
7. MANAGEMENT & TREATMENT¶
Management is based on treatment of the underlying condition causing sensory disturbance. Symptomatic treatment addresses persistent dysesthesias.
Pharmacologic Treatment of Persistent Dysesthesias¶
| Drug Class | Medication | Dose Range (mg/day) |
|---|---|---|
| Anticonvulsant | Carbamazepine | 100–1000 |
| Anticonvulsant | Gabapentin | 300–3600 |
| Anticonvulsant | Pregabalin | 50–300 |
| Tricyclic antidepressant | Amitriptyline | 25–150 |
| Tricyclic antidepressant | Nortriptyline | 25–150 |
| Tricyclic antidepressant | Desipramine | 100–300 |
| SNRI | Venlafaxine | 75–225 |
7.1 Treatment of Underlying Conditions¶
Specific treatment depends on identified etiology: - Metabolic correction (diabetes control, B12 replacement) - Immunotherapy for inflammatory conditions - Tumor treatment for paraneoplastic syndromes - Surgical decompression for structural lesions
7.2 Symptomatic Treatment of Dysesthesias¶
For severe, persistent dysesthesias, the following medications may be effective: Anticonvulsants: - Carbamazepine: 100–1000 mg/day - Gabapentin: 300–3600 mg/day - Pregabalin: 50–300 mg/day Antidepressants: - Amitriptyline: 25–150 mg/day - Nortriptyline: 25–150 mg/day - Desipramine: 100–300 mg/day - Venlafaxine: 75–225 mg/day Note: Acute and chronic pain management is addressed separately in Chapter 14.
8. KEY CLINICAL PEARLS¶
Essential clinical teaching points for examination and practice.
Clinical Pearls: Sensory Examination and Localization¶
| Pearl | Clinical Application |
|---|---|
| 50% axon loss rule | Clinical examination may be normal until ‡50% of afferent axons are lost; subclinical disease detected by nerve conduction studies |
| Sensory signs are always negative phenomena | Examination demonstrates loss of function, not positive symptoms |
| Length-dependent means feet first | In polyneuropathy, symptoms reach knees before appearing in fingertips |
| Dissociated sensory loss | Selective modality impairment indicates either small-fiber neuropathy (peripheral) or spinothalamic tract lesion (central) |
| Brown-Séquard pattern | Ipsilateral proprioception loss + contralateral pain/temperature loss = cord hemisection |
| Crossed face-body pattern | Ipsilateral facial + contralateral body sensory loss = lateral medullary lesion |
| Lhermitte's sign | Electric shock down spine with neck flexion = cervical cord lesion (MS, spondylosis, radiation) |
| Romberg sign interpretation | Positive Romberg indicates proprioceptive (posterior column) dysfunction, not cerebellar disease |
| Pseudothalamic syndrome | Anterior parietal infarct can mimic thalamic hemisensory loss |
| Psychogenic diagnosis requires positive findings | Do not diagnose by exclusion; look for midline splitting, inconsistency, non-anatomic patterns |
9. FURTHER READING¶
Recommended References: - Brazis P et al: Localization in Clinical Neurology, 8th ed. Philadelphia, Lippincott Williams & Wilkins, 2021. - Campbell WW, Barohn RJ: DeJong's The Neurological Examination, 8th ed. Philadelphia, Lippincott Williams & Wilkins, 2019. - O'Brien M on behalf of the Guarantors of Brain: Aids to the Examination of the Peripheral Nervous System, 6th ed. Amsterdam, Elsevier, 2023. - Waxman S: Clinical Neuroanatomy, 30th ed. New York, McGraw Hill Education, 2024.