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peripheral neuropathy a brief overview 1
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- 2. Introduction • Generalized term •Sensory nerves, motor nerves, or both • May affect one nerve (mononeuropathy), several nerves together (polyneuropathy) or several nerves not contiguous (Mononeuropathy multiplex) • cell body (e.g., neuronopathy or ganglionopathy), myelin (myelinopathy), and the axon (axonopathy)
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- 4. Motor Symptoms Negative symptomsPositive symptoms Motor Nerves: Large Fibre Wasting Hypotonia Weakness Hyporeflexia Fasciculation Cramps
- 5. Sensory Symptoms Negative symptomsPositive symptoms Sensory: Large Fibre Decreased Vibration Decreased Proprioception Hyporeflexia Sensory Ataxia Paresthesias Sensory: Small Fibre Decreased Pain Decreased Temperature Dysesthesias Allodynia
- 6. Autonomic Symptoms Negative SymptomsPositive Symptoms Autonomic Nerves Decreased Sweating Hypotension Urinary retention Impotence Vascular color change GI Complaints Increased Sweating Hypertension
- 7. Causes Systemic disorders – Endocrine– DM, hypothyroidism, acromegaly – Connective tissue – Sjogren, RA, SLE, MCTD, Vasculitis – Nutritional – B complex ( B1, niacin, B6, B12 ), vitamin E, copper, B6 overdose – Inflammatory – AIDP, CIDP, Amyloidosis, Sarcoidosis, hypereosinophilic syndrome, IBD, celiac disease – Metabolic – CLD, Uremia, Porphyria – Infective – Leprosy, HIV, Diphtheria, Lyme, Hep B & C – Malignancy – Paraneoplastic, Infiltration by leukemia & lymphoma, Plasma cell disorders 8. Critical care neuropathy
- 8. Systemic disorders – Toxic( Drugs/toxin ) – Hereditary – CMT –M/C – Environmental – Vibration induced, prolonged cold exposure, hypoxemia – Idiopathic – 46%. Most cases > 50 years. Progression – slowly over months to years. Predominant sensory symptoms. Proposed but unproven causes are HTn, dyslipidemia, increased oxidative stress.
- 9. Drugs and Toxins DRUGS •Metronidazole • Chloroquine and hydroxychloroquine • Amiodarone • Colchicine • Thalidomide • Dapsone • Nitrofurantoin • Pyridoxine • Isoniazid • Ethambutol • Phenytoin • Lithium TOXINS • Organophosphates • Lead • Mercury • Thallium • Arsenic • Gold • Hexacarbon • Ethylene Oxide • Carbon disulfide
- 11. Mononeuropathy • Local process: –Direct trauma – Compression or entrapment – Vascular lesions – Neoplastic compression or infiltration – CARPAL TUNNEL SYNDROME
- 12. Mononeuropathy Multiplex • Simultaneous/sequential damage to multiple noncontiguous nerves. • Ischemia caused by vasculitis • Microangiopathy in diabetes mellitus • Less common causes : Granulomatous, leukemic, or neoplastic infiltration, Hansen's disease (leprosy) and sarcoidosis.
- 13. Polyneuropathy • Characterized bysymmetrical, distal motor and sensory deficits that have a graded increase in severity distally and by distal attenuation of reflexes, • Rarely predominantly proximal:(E.g: acute intermittent porphyria). • The sensory deficits generally follow a length-dependent stocking-glove pattern • DIABETES
- 15. Axonopathies • By farthe majority of the toxic, metabolic and endocrine causes • NCVs: CMAPs ↓ 80% lower limit of normal w/o or min velocity or distal motor latency change. • Legs>> arms. • EMG: Signs of denervation (acute, chronic) and reinnervation
- 16. Myelinopathies • Unusual bycomparison with axonopathies • Clues – hypertrophic nerves on exam, global areflexia, weakness without wasting, motor >> sensory deficits • NCS – Distal motor latency prolonged (>125% ULN), Conduction velocities slowed (<80% LLN) May have conduction block • EMG – Reduced recruitment w/o much denervation
- 20. Approach • In approachinga patient with a neuropathy, the clinician has three main goals: – identify where the lesion is, – identify the cause, and – determine the proper treatment. • The first goal is accomplished by obtaining a thorough history, neurologic examination, and electrodiagnostic and other laboratory studies. While gathering this information, seven key questions are asked, the answers to which can usually identify the category of pathology that is present.
- 24. Evaluation • Mild symptomswith known underlying lesion like DM, chemotherapy, alcohol abuse – No evaluation is required • Feature warranting a full evaluation – Assymetry – Non length dependence – Motor predominance – Acute onset – Predominant autonomic involvement – Rapidly progressive symptoms – Sensory ataxia
- 25. Acute / AbruptOnset • GBS • Vasculitis • Porphyria • Infectious Disease (Lyme Disease, Diphthermia) • Toxin / Drug- arsenic, thallium, chemotherapeutic agents, despone
- 26. Subacute / Chronic •CIDP • DM • Vasculitis • HIV • Vitamin B12 Deficiency • Copper Deficiency • Paraneoplastic • Sjogren Syndrome • Toxin, Drug
- 27. Relapse and RemittingCourse • CIDP • Porphyria • HNPP
- 28. History • The temporalcourse of a neuropathy varies, based on the etiology. – With trauma or ischemic infarction, the onset will be acute, with the most severe symptoms at onset. – Inflammatory and some metabolic neuropathies have a subacute course extending over days to weeks. – A chronic course over weeks to months is the hallmark of most toxic and metabolic neuropathies.
- 29. • A chronic,slowly progressive neuropathy over many years occurs with most hereditary neuropathies or with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). • Neuropathies with a relapsing and remitting course include CIDP, acute porphyria, Refsum's disease, hereditary neuropathy with liability to pressure palsies (HNPP), familial brachial plexus neuropathy, and repeated episodes of toxin exposure.
- 30. • Ischemic neuropathiesoften have pain as a prominent feature. • Small-fiber neuropathies often present with burning pain, lightning-like or lancinating pain, aching, or uncomfortable paresthesias (dysesthesias). • Dying-back (distal symmetric axonal) neuropathies initially involve the tips of the toes and progress proximally in a stocking-glove distribution. • Peripheral neuropathy can present as restless leg syndrome. • Proximal involvement may result in difficulty climbing stairs, getting out of a chair, lifting and bulbar involvement can also be seen
- 32. Recommendations for LabTesting • Screening laboratory tests may be considered for all patients with DSP. • Tests with the highest yield of abnormality: – Blood glucose (fasting) – Serum B12 with metabolites (methylmalonic acid, homocysteine) – SPEP(serum protein electrophoresis).
- 33. • ANA, RF,Anti-dsDNA, Anti-Ro, Anti-La, ANCA screen, cryoglobulins • Urine for heavy metals, porphyrins • IFE/urine IFE/ plasma light chain analysis
- 34. Neuropathies + SerumAutoantibodies • Antibodies against Gangliosides – GM1 : Multifocal motor neuropathy – GM1, GD1a : Guillain-Barré syndrome – GQ1b : Miller Fisher variant • Antibodies against Glycoproteins – Myelin-associated glycoprotein : MGUS • Antibodies against RNA-binding proteins – Anti-Hu, antineuronal nuclear antibody 1: Malignant inflammatory polyganglionopathy
- 35. Electrodiagnostic Studies • Confirmingthe presence of neuropathy • Locating focal nerve lesions • Nature of the underlying nerve pathology
- 37. Laboratory Evaluation • Thelimitations of EMG/NCS should be taken into account when interpreting the findings. – There is no reliable means of studying proximal sensory nerves. – NCS results can be normal in patients with small-fiber neuropathies – Lower extremity sensory responses can be absent in normal elderly patients. • EMG/NCS are not substitutes for a good clinical examination.
- 38. Nerve Biopsy • Invasculitis, amyloid neuropathy, leprosy, CIDP, Inherited disorders of myelin, and rare axonopathies • The Sural nerve is selected most commonly • The superficial peroneal nerve – alternative; :advantage of allowing simultaneous biopsy of the peroneus brevis muscle through the same incision. • This combined nerve and muscle biopsy procedure increases the yield of identifying suspected vasculitis.
- 40. Skin Biopsy • Smallfibre neuropathy • Very small piece of skin just proximal to ankle is removed. • Special stains are applied: Qualitative assessment or by careful counting to determine intraepidermal nerve fibre.
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