17. Peripheral Neuropathy.ppt

UL power 4/5 LL hip flexors, quadriceps, and hamstrings were 4/5 bilaterally; dorsiflexors and plantar flexors were 3/5 bilaterally. Her sensation was intact on upper extremities but diminished to touch and pin prick on lower extremities and abdomen. Her gait was ataxic, Deep tendon reflex (DTR) dim...

UL power 4/5 LL hip flexors, quadriceps, and hamstrings were 4/5 bilaterally; dorsiflexors and plantar flexors were 3/5 bilaterally. Her sensation was intact on upper extremities but diminished to touch and pin prick on lower extremities and abdomen. Her gait was ataxic, Deep tendon reflex (DTR) diminished to absent What is your diagnosis? PERIPHERAL NEUROPATHY The Motor Unit From Dumitru, D. Electrodiagnostic Medicine, Hanley & Belfus. Philadelphia. 1995 The four anatomic stations underlying lower motor neuron weakness Source publication How then are we to sort through the causes to make an etiologic diagnosis?... Use the 6 D’s…. 1. 2. 3. 4. 5. 6. What is the distribution of the deficits? What is the duration? What are the deficits (which fibers are involved)? What is the disease pathology (axonal or demyelinating or mixed) What is the etiology ? Is there an inherited (developmental) neuropathy? Is there drug/toxin exposure? The patterns of peripheral neuropathy… • Mononeuropathy? • Polyneuropathy? multiple nerves contiguous typically length dependent (“stocking-glove”) Polyneuropathy is common! 2.4% (8% over 55 yr) www.ama-assn.org/ ama/pub/category/7172.html 1. What is the distribution of the deficits? • Asymmetry 1. Mononeuropathy 2. Mononeuritis multiplex – e.g. vasculitis median, ulnar, peroneal nerve lesions • Symmetric (glove/stocking) = polyneuropathy 2. What is the duration? Ask: Acute or Chronic? • Most polyneuropathies are chronic – ++months-yrs • Acute polyneuropathies e.g. Guillain Barre syndrome Vasculitis • Chronic /Relapses and remissions • e.g.Hereditary / Intermittent toxin exposure 3. What are the deficits (which fibers affected)? • If predominant motor fibers think of: Guillain Barre syndrome Lead toxicity Charcot-Marie-Tooth disease • If pure sensory/ severe proprioceptive deficit, think of sensory neuropathy: Carcinoma (paraneoplastic) Vitamin B6 toxicity • If autonomic nerves involved (small fiber) think of: Diabetes Amyloid Drugs like vincristine, ddI, ddC 4. What is the disease pathology? Axonal or demyelinating? The vast majority are axonal. •If otherwise unremarkable chronic sensorimotor axonal polyneuropathy… exclude alchohol, diabetes, hypothyroidism, uremia, B12 deficiency & monoclonal gammopathy •Demyelination a key finding because its causes are relatively few. •If demyelination uniform the cause is hereditary. e.g. Charcot-Marie Tooth type I (HMSN), GBS The two types of peripheral neuropathies: axonopathies and myelinopathies From Kumar: Robbins and Cotran: Pathologic Basis of Disease, 7th ed. http://www.neuro.wustl.edu/neuromuscular/nother/skel.html#nosteo Question #2. What is the etiology? Only a limited number of ways a peripheral nerve can react to injury, thus a multitude of different etiologies can cause similar effects… Etiology? Inherited: e.g. Charcot-Marie-Tooth disease (HMSN) Infectious: e.g. Leprosy Inflammatory: e.g. Guillain Barre syndrome (AIDP) Neoplastic: e.g. lung cancer Metabolic: e.g. Diabetes Drug: e.g. Vincristine Toxic: e.g. Ethanol Charcot-MarieTooth disease 5. Is there an inherited (developmental) neuropathy? • Among the most common! • Clues – orthopedic deformities (feet, spine) – long duration – indolent progression – few “positive” symptoms – examine/question the family members! 6. Drug or toxin exposure? Demyelinating e.g. Glue sniffing Arsenic Axonal e.g. Cancer drugs like vincristine and paclitaxel chloroquine, ethambutol, isoniazid and metronidazole Cardiac medications like amiodarone A 36-year-old woman who presented to the outpatient clinic with complaints of numbness, tingling, and weakness in her legs. How would you proceed to examine her ? Motor examination inspection: wasting, faciculation tone hypotonia power reduced reflexes diminished ; plantar - flexor Sensory examination touch,pain, vibration, proprioception Expected sensory loss peripheries- feet upwards Any other examination? Rhomberg’s/Gait What is your diagnosis? PERIPHERAL NEUROPATHY www.neuro.wustl.edu/neuromuscular/pics/people/patients/Hands/handatrophymnd3.jpg Signs and symptoms of peripheral neuropathy might include: Gradual onset of numbness, prickling or tingling in your feet or hands, which can spread upward into your legs and arms. Sharp, jabbing, throbbing, freezing or burning pain. Extreme sensitivity to touch. Lack of coordination and falling. Guillain-Barre Syndrome GBS Eponym that encompasses acute immunemediated polyneuropathies Peripheral nerve myelin is target of an immune attack Starts at level of nerve root=conduction Eventually get widespread patchy demyelination= increased paralysis Pathophysiology Usually postinfectious Immune-mediated: infectious agents thought to induce Ab production against specific gangliosides/glycolipids Lymphocytic infiltration of spinal roots/peripheral nerves & then macrophage-mediated, multifocal stripping of myelin Result: defects in the propagation of electrical nerve impulses, with eventual conduction block and flaccid paralysis Clinical Features: Progressive, fairly symmetric muscle weakness -typically starts in legs -10% will 1st develop weakness in face or arms -severe resp muscle weakness in 1030% pts -oropharyngeal weakness in ~ 50% Clinical Features: Absent or depressed DTR Often prominent severe pain in lower back Common to have paresthesias in hands and feet Dysautonomia is very common: tachycardia, urinary retention, hypertenison alternating w/ hypotension, ileus Diagnosis: Albuminocytologic dissociation: elevated CSF protein w/ normal WBC (80-90% pts) Electromyography (EMG) helps confirm diagnosis GBS=heterogenous syndrome w/ variant forms Think of AIDP as the traditional form as described previously, accts for 85-90% Miller Fisher Syndrome: opthalmoplegia, ataxia, and areflexia (5%). GQ1b antibody. Only 1/4th w/ extremity weakness AMAN: selective involv of motor nerves, DTRs are preserved, more common in Japan/China, almost all preceded by Campylobacter infxn AMSAN: more severe form of AMAN +sensory Disease Modifying Treatment IVIG : typically given for 5 d at 0.4 gram/kg/d (may need to extend course depending on response) Plasmapheresis: usually 4-6 treatments over 810 days The choice b/w plasma exchange and IVIG is dep on availability, pt contraindications, etc. Because of ease of administration, IVIG is frequently preferred. The cost and efficacy of the 2 treatments are comparable. Glucocorticoids have NO ROLE!! Supportive Care Monitor Resp status closely up to 30% may req ventilatory support In severe cases, intrarterial monitoring may be necessary given the significant blood pressure fluctuations Neuropathic pain plagues most, often managed w/ Gabapentin or Carbamazepine Outcomes: 65% can walk independently @ 6 mos Overall, 80% usually recover completely 5-10% have prolonged course w/ incomplete recovery, ~3% wheelchair bound Approx 5% die despite ICU care 2% will develop chronic relapsing Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP) THANK YOU