Peripheral neuropathy
- 2. Peripher al Ner ve Myelin : Current cannot flow Axon : Not nerves left
- 3. Types of nerve fibers Diameter Conduction Function microns Velocity m/s A alpha 1-20 70-110 Motor, Proprioception beta 5-10 30-60 Touch gama 3-6 20-30 Fusimotor, spindles delta 2-5 20-30 Sharp pain B <3 5-15 Autonomic, pregangl. C <1.3 0.5-2 Slow pain Non myelinated
- 4. T he Peripher al Ner vous System Motor: weakness, atrophy Sensory loss Large Fibers (position) Small fiber (pain) Reflex loss Autonomic symptoms (redness, dizziness, ED)
- 6. Definitions Neuropathy Pathological process affecting a peripheral nerve/s Mononeuropathy A single nerve affected Mononeuritis multiplex Multiple mononeuropathy or Multifocal neuropathy
- 7. Polyneuropathy Diffuse symmetrical disease usually beginning peripherally Acute/Chronic Static/Prog Relapsing/Recovering Motor Sensory Sensrimotor(Mixed) Autonomic Demyelinating Axonal Radiculopathy Nerve root disease
- 8. Mechanisms of damage Demyelination Myelin sheath disrupted GBS Post Diphtheric HSMN Axonal degeneration Axon damage Toxic neuropathies Wallerian degeneration Nerve section Compression Focal demyelination Entrapment-Carpel tunnel syndrome Infarction Arteritis Polyarteritis nodosa Churg-Strauss synd. DM Infiltration Infiltration Leprosy Sarcoidosis
- 9. Classification EXAMINATION FINDINGS Purely Motor or Sensory or Sensorimotor? Proximal or distal? Symmetric or asymmetric? Multifocal, generalized, regional? Upper limbs, lower limbs, neck, trunk? TIMING Acute or chronic?
- 10. ASSOCIATED FINDINGS Painful or painless? Hereditary or sporadic? ELECTRODIAGNOSIS Axonal or demyelinating? LABORATORY Paraprotein present? Type? Antibody against nerve? CSF protein level? HISTOLOGY Inflammatory Cells
- 11. Epidemiology Prevalence ~ 2.4% ~ 8% in people older than 55 years DM is most common cause
- 12. Epidemiology Other common systemic causes Metabolic disorders Infectious agents Vasculitis Toxins Drugs Autoimmunity Inherited
- 13. Diagnosis Most important details to determine Distribution Duration Course
- 14. Diagnosis Clinical manifestations vary widely Altered sensation Pain Muscle weakness or atrophy Autonomic symptoms
- 15. Labor ator y Screening for “Treatable” Neuropathy? B12 Not truly length-dependent Diabetes This type of neuropathy generally a late finding ANA, chronic disease Screen for connective tissue screen diseases (late finding) TSH If positive, have you proven anything? ESR If onset is recent HIV Risk Factors Review medications Big question
- 16. Diagnosis Electro diagnostic studies Sensitive, specific, validated Extension of neurologic exam Nerve conduction studies (NCS) Needle electromyography (EMG)
- 17. Diagnosis Establish distribution Mononeuropathy Mononeuropathy multiplex Polyneuropathy Determine primary pathology Demyelinating Axonal
- 18. Mononeuropathy Focal lesion involving a single nerve Electro diagnostic studies indispensible Localize site of injury Determine severity of lesion
- 19. Mononeuropathy Causes Entrapment Carpal tunnel syndrome is most common Foot drop Focal compression Trauma
- 20. Mononeuropathy Multiplex Separate/noncontiguous involvement Simultaneously Serially Pattern Random Multifocal Frequently evolves quickly
- 21. Mononeuropathy Multiplex Urgent assessment for vasculitis Polyarteritis nodosa Churg-Strauss disease Connective tissue diseases Rheumatoid arthritis Sjogren’s syndrome
- 22. Polyneuropathy Most commonly distal symmetrical Fiber effect is length-dependent Toes and soles affected first Associations Systemic diseases Metabolic disorders Exogenous toxins
- 23. Polyneuropathy Diabetes is prototype Chronic, sensory and motor Commonest in developed world Alcoholism is the second most common
- 24. Polyneuropathy Early symptoms Sensory abnormalities Numbness Burning Paresthesias Dysesthesias Distally predominant Symmetrical
- 25. Polyneuropathy Evolution is centripetal Symptoms spread up legs Sensory loss Dysesthesias Ankles jerks are depressed Patients have trouble walking on their heels Foot plantar flexion remains strong
- 26. Polyneuropathy Symptoms noticed in fingertips Numbness Dysesthesias Advanced picture is easily recognizable Stocking-glove sensory loss Distal muscle wasting and weakness Absent tendon reflexes
- 27. Polyneuropathy Sub classification Historical features are indispensible Other medical conditions Symptoms of systemic disease Recent viral or other infectious diseases Recent vaccinations Institution of new medications
- 28. Polyneuropathy Exposure to toxins Alcohol Heavy metals Organic solvents Family history Duration and clinical course are helpful Acute = days to weeks Chronic = months to years
- 29. Laboratory Investigations CBC UREA SUGAR TFTs B12 Methylmalonic acid ESR Homocysteine CRP Folate
- 30. Treatment General Subtype specific Diabetes mellitus Renal insufficiency Hypothyroidism Vitamin B12 deficiency Systemic vasculitis
- 31. Treatment General Pain Antiepileptic drugs Antidepressants Tramadol
- 32. Treatment Preventative and palliative Weight reduction Assiduous foot care Good shoes Ankle-foot orthoses as needed Several organizations provide support
- 33. Chronic Length Dependent Neuropathy Begins in toes or feet Stocking distribution Progresses rostrally Tops and bottoms of feet Weakness begins in ankles when sensation reaches calves Sometimes diagnosable, Never treatable?
- 34. Phenotype CIDP Small Differential
- 35. Phenotype-MADSAM Neur opathy Key DDx: Brachial plexopathies Vasculitis mononeuropathy multiplex Compression neuropathies HNPP (genetic testing)
- 36. Multifocal Motor Neur opathy (MMN) Almost always in hands and wrists Pattern of weakness is in the distribution of individual peripheral nerves i.e. severe involvement in ulnar distribution sparing median Lack of atrophy in weak muscles No pathological reflexes
- 37. Uncertainty Many cases are not easily definable because of multiplicity of patterns Cases that are not clearly untreatable are possibly treatable