Numbness, Tingling, Pain and Weakness:

EVALUATING THE PATIENT WITH A PERIPHERAL NEUROPATHY

Peter D. Donofrio, M.D.Department of Neurology

Vanderbilt University School of Medicine

EVALUATING THE PATIENT WITH A PERIPHERAL NEUROPATHY

Introduction

• Focused General and Neurologic Examination• Edx Study as Extension of the Neurologic Examination• Sensory Nerve Conduction Studies• Motor Nerve Conduction Studies• Late Responses• Needle Electromyography (EMG)• Autonomic Nervous System Testing

Table 1Features of the Clinical Examination Important in the

Evaluation of Suspected Neuropathy

General InformationOnset and temporal profile of motor, sensory, and autonomic complaints.Type and distribution of paresthesia, hyperesthesia and hyperpathia.Distribution of weakness.Industrial and medical history for toxin or drug exposures.Family history, including bony deformities such as pes cavus or hammer toes.Social habits including recreational drug use.Antecedent illness or symptoms of underlying disease.

Table 1 (continued)Features of the Clinical Examination Important in the

Evaluation of Suspected Neuropathy

Clinical ExaminationGeneral

Findings most prominent in distal lower extremities.Relative symmetry.Associated findings such as ataxia, tremor, skin lesions, bonydeformities (pes cavus or hammer toes).Palpate peripheral nerves (tenderness, paresthesia, hypertrophy).

Motor (emphasis upon distal muscles)Intrinsic hand muscles, finger and wrists extensors.Toe extensors and foot dorsiflexors.

Table 1 (continued)Features of the Clinical Examination Important in the

Evaluation of Suspected Neuropathy

SensoryDemonstrate distal to proximal sensory loss gradient.Identify involved modalities.

Large fiber: vibration, light-touch, touch-pressure (common); joint position sensation (JPS) when severe.Small fiber: temperature, pin-pain, deep pain.

Discriminative sensations less helpful in peripheral disorders.Absence of sensory level on the trunk.Vibratory loss to iliac crest and JPS loss may suggest spinal cord lesion.

Table 1 (continued)Features of the Clinical Examination Important in the

Evaluation of Suspected Neuropathy

ReflexesAchilles reflexes usually absent.Diffusely hypoactive reflexes not necessarily abnormal.Absence of pathologic reflexes (e.g., Babinski response).

Autonomic Nervous SystemPostural hypotension.Sluggish pupillary reaction to light.Abnormality of sweating.Bowel, bladder, or sexual dysfunction.Vasomotor changes in the feet more than hands.

Table 2Expectations for the Edx Evaluation of Neuropathy

Document evidence of a peripheral abnormalityDetect presence.Document location (diffuse, focal, multifocal).

Identify peripheral modalities involvedSensory fibers.Motor fibers.Autonomic fibers.

Table 2 (continued)Expectations for the Edx Evaluation of Neuropathy

Identify the predominant pathophysiologyAxonal loss.Uniform demyelination.Multifocal demyelination with partial or complete conduction block.Conduction slowing suggestive of membranopathy.Combination of above.

Establish temporal profile when possible (acute, chronic, old, ongoing)Exclude accompanying or alternative disordersDetermine prognosis

Table 3Checklist: Evaluating the Edx Report

Clinical findings consistent with your evaluation?Limb temperatures monitored and recorded?Cool limbs warmed (31°C to 32°C minimum)?Measurement techniques described?Individual measures reported?

Sensory studies (amp, DL, CV).Motor studies (amp, DL, CV, F-wave latency).Needle examination (insertional activity, fibrillation potentials, MUAP recruitment, amp, and % poly).

Table 3 (continued)Checklist: Evaluating the Edx Report

Presence or absence of partial or complete conduction block described?Normal values provided?Sufficient evaluation to

Document the problem?Exclude alternative explanations (avoid errors of omission)?

Appropriate negative findings described?Interpretation consistent with clinical findings?

Figure 1

Figure 2

Figure 3

Clinical Examinations in Neurology, 1976

Needle Examination

Table 4Proposed Edx Studies in Evaluating Neuropathy

Strategy differs depending upon severityTest most involved site if mild or moderate.Test least involved site if severe.

Peroneal motor. If no response:Tibial motor.

If no peroneal or tibial responses, study:Peroneal motor, recording anterior tibialis.Ulnar motor.Median motor.

Table 4 (continued)Proposed Edx Studies in Evaluating Neuropathy

Sural sensoryMedian sensoryTest Additional nerves if finding equivocalDefinite abnormalities should result in test of:

Opposite extremity.Evaluation of suspected abnormality.

Table 5Motor or Motor > Sensory, Axonal Loss

Polyneuropathy

Charcot-Marie-Tooth Disease (Hereditary Motor Sensory Neuropathy Type II)

DapsoneDisulfiramAcute motor axonal neuropathy (AMAN)Acute motor sensory axonal neuropathy (AMSAN)HyperinsulinismNitrofurantoinOrganophosphate PoisoningPorphyriaParaneoplastic motor neuropathy (lymphoma or carcinoma)Vincristine Toxicity

Charcot-Marie-Tooth Disease

Table 6Motor > Sensory, Uniform Conduction Slowing

Polyneuropathy

AmiodaroneCharcot-Marie-Tooth Disease Type I (Hereditary Motor Sensory

Neuropathy Type I)Cytosine arabinoside (ara-C)Dejerine-Sottas disease (Hereditary Motor Sensory Neuropathy Type III)DoxorubicinHexacarbon ToxicityPerhexiline maleateSodium channel blockers

Table 7Motor > Sensory, Multifocal Conduction Slowing

Polyneuropathy

Arsenic (acute intoxication)Acute Inflammatory Demyelinating Polyneuropathy (AIDP)Subacute Inflammatory Demyelinating Polyneuropathy (SIDP)Chronic inflammatory demyelinating polyneuropathy (CIDP)Chronic dysimmune polyneuropathy

Monoclonal gammopathy of undetermined significance (MGUS)Osteosclerotic myelomaMultiple myeloma (substantial proportions are axonal)

Table 7 (continued)Motor > Sensory, Multifocal Conduction Slowing

Polyneuropathy

Systemic lupus erythematousWaldenstrom’s macroglobulinemiaGamma heavy chain diseaseCryoglobulinemiaCastleman’s diseaseLymphomaCarcinomaHIV

Multifocal motor neuropathy (MMN) with conduction block

Figure 4

Table 8Sensory, Axonal Loss

Polyneuropathy

CisplatinCongenitalMetronidazoleParaneoplastic

PyridoxineSjögren’s syndromeStyreneThalidomide

Table 9Sensory > Motor, Axonal Loss

Polyneuropathy

AcromegalyAmyloidosisCritical illness neuropathyConnective tissue diseases

Rheumatoid arthritisPeriarteritis nodosaChurg-Strauss vasculitis

Degenerative disordersFriedreich’s ataxiaOlivopontocerebellar

PharmaceuticalsAmitriptylineColchicineEthambutolIsonicotine hydrazine (INH)MetronidazoleNitrous oxidePhenytoinThalliumVincristine

Table 9 (continued)Sensory > Motor, Axonal Loss

Polyneuropathy

GoutHypothyroidismMetals

Arsenic (chronic)GoldLithiumMercury

NutritionalB12 deficiencyFolate deficiencyPost-gastrectomyThiamine deficiency

Polycythemia veraSarcoidosisToxic

AcrylamideCarbon disulfideEthyl alcoholHexacarbons (glue sniffing)Organophosphorous esters

Multiple myelomaMyotonic dystrophy

Rheumatoid ArthritisVasculitic Neuropathy

Table 10Sensory and Motor, Conduction Slowing

and Axon-Loss Polyneuropathy

Diabetes mellitusEnd-stage renal disease

Interpretation of NCS ResultsHelpful Tips

Absent responses unhelpful => axon loss vs. demyelination.SNAPs normal in lesions proximal to DRG.SNAPs abnormal in lesions distal to DRG.Weak + atrophy + low CMAPs => LMN process.Low CMAPs => any LMN process including myopathy.

Electrodiagnostic ConsultantImportant Role

Exclude disorders that mimic or complicate neuropathyPolyradiculopathyAnterior horn cell disorderMononeuritis multiplexDistal myopathiesNeuromuscular junction disordersMyelopathies

EVALUATING THE PATIENT WITH A PERIPHERAL NEUROPATHY

Summary

• Confirm or Refute Presence of Neuropathy• Identify Fibers Affected• Identify Predominant Pathophysiology• Suggest Temporal Profile (Acute, Subacute, Chronic,

Ongoing)• Document Location (Diffuse, Focal, Multifocal)• Parallel Clinical Exam• Create Focused List of Differential Diagnosis