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Neurology C ase P resentation August 31 st , 2012

Neurology C ase P resentation August 31 st , 2012. Dipika Aggarwal PGY 4 Neurology. Teen aged male admitted with acute onset generalized weakness for 1 day duration Woke up with diffuse weakness; no anti gravity strength in arms, unable to get out of bed

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Neurology C ase P resentation August 31 st , 2012

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  1. Neurology Case PresentationAugust 31st, 2012 DipikaAggarwal PGY 4 Neurology

  2. Teen aged male admitted with acute onset generalized weakness for 1 day duration • Woke up with diffuse weakness; no anti gravity strength in arms, unable to get out of bed • Proximal > distal weakness; bilaterally symmetrical • Denied diplopia, dysphagia, dysarthria, facial droop, drooling or change in level of consciousness

  3. Denied any sensory complains • Denied trouble breathing, urinary or bowel incontinence • Denied any recent illness, trauma, travel or tick bite • One episode of non-bloody emesis prior to admission

  4. PMH: similar episode four months earlier, admitted to OSH for 4-5 days, ?? Diagnosed with GBS, ?? treated with plasmapheresis, no LP/ EMG • PSH: none • Home meds: None • FH: HTN, migraine, DM, asthma, no similar problem in family members • SH: denies smoking, ETOH or illicit drug use

  5. Physical exam • Vitals stable • General physical exam unremarkable • Neurological exam • Mental status: AAO * 4 • Speech : fluent with comprehension intact • CN 2-12: PERRLA, EOMI, normal facial sensation and symmetry, normal facial strength, hearing intact, equal palatal elevation and tongue midline

  6. Motor: Flaccid tone, motor strength 2/5 proximally and 3-4/5 distally BUE and BLE • DTRs: Areflexic , toes downgoing • Sensory: Intact to LT/PP/ Vibration and proprioception • Unable to test for cerebellar function and gait

  7. Where?? What??

  8. Labs • Hb - 14.6, WBC 6.1, Plt count 215 • Sodium 143, K 1.3, Chloride 110, BUN 13, Creatinine 0.83, Glucose 151, Calcium 9.3, Magnesium 2.0, Phosphorus 2.4 • CK 493, Aldolase 15.7 (on day 3) • TSH: 2.082, free T3 – 3.8, free T4 – 0.9 • Urine lytes: unremarkable

  9. Hospital course • Aggressive Potassium replacement • Started showing improvement in muscle strength on day 1 • By day 2 – strength was 5/5 BUE and BLE • Diagnosed with familial hypokalemic periodic paralysis • Discharged with follow up care with Jayhawk clinic

  10. Muscle channelopathies • Non dystrophic myotonias • Myotoniacongenita (CLCN1) • Paramyotoniacongenita (SCN4A) • Sodium channel myotonias (potassium aggravated myotonias) (SCN4A) • Periodic paralyses • Hypokalemic (CACNA1S/ SCN4A) • Hyperkalemic(SCN4A) • Anderson Tawil syndrome (KCNJ2)

  11. Periodic Paralysis Secondary • Hypokalemic: • Thyrotoxicperiodic paralysis • hyperaldosteronism • RTA • villous adenoma • cocaine binge • diuretics, licorice, steroids, ETOH • Hyperkalemic (k>7): • hyporenemichypoaldosteronism (DM/CRF) • oral K, CRF, chronic heparin, rhabdomyolysis • Normakalemic: • Guanidine, sleep paralysis, MG, TIA, conversion

  12. Hypokalemic periodic paralysis • HypoKPP1 and 2 - CACNA1S/ SCN4A gene • HypoKPP 1 is the most frequent form • 1 in 100,000 • Autosomal dominant inheritance pattern • M:F – 3 or 4:1 • Onset: first 2 decades of life

  13. Clinical features • Flaccid paralysis – mild focal weakness to severe generalized weakness • Occur anytime of the day; more common in morning • Absence of myotonia • Proximal > distal weakness; legs > arms • Sparing of facial, ventilatory and sphincter muscles • Lasts several hours to more than a day

  14. Frequency: highly variable • Frequency decreases after age 30; may become attack free in 40s and 50s • Permanent fixed weakness or slowly progressive weakness more common with HypoKPP1 • Attacks may be preceded by sensation of heaviness and or aching in the low back

  15. Precipitating factors • Strenuous physical activity followed by rest or sleep • High carb diet • ETOH consumption • Emotional stress • Concurrent viral illness • Lack of sleep • Medications like beta agonists, corticosteroids, and insulin

  16. Hypokalemic Periodic ParalysisGenetics • Mutations in voltage sensor segment D2S4 of 1 subunit of skeletal muscle Ca channel gene, chromosome 1q • Arg528His, Arg1239His, Arg1239Gly • Less commonly SCN4A mutation enhances Na inactivation

  17. Hypokalemic Periodic ParalysisPathophysiology • The mutation slows the activation rate of L-type Ca current to 30% of NL • Reduced RYR1-mediated Ca release from SER • Reduced calcium current density • Impaired E-C coupling • ? role of K and ? inexcitability • Ca homeostasis change reduces ATP-dependent K channel current and leads to abnormal depolarization (Tricarico D et al 1999)

  18. Diagnostic studies • Serum K < 3.0mEq/L • Serum CK level elevated • EKG changes – U waves, flattening of T waves • Provocative testing - Intravenous glucose load/ insulin • Electrophysiology • Sensory and motor NCS normal between attacks • During attacks – small CMAP. Reduced insertional activity, fibs and positive sharp waves • No myotonia on EMG • Short/ long exercise test

  19. Periodic ParalysisMuscle Pathology • Muscle biopsy reserved to atypical patients with normal provocative and gene testing • Vacuoles reflect permanent myopathy • Vacuoles represent proliferation, degeneration and autophagic destruction of T-tubules & SR • Large central vacuoles in hypokalemic PP

  20. Hypokalemic Periodic Paralysis

  21. Treatment • Reducing exposure to known triggers • Acute treatment – replacement of K • Acetazolamide – prevent attack recurrence and severity • Acetazolamide may ppt weakness in HypoKPP2 • Dichlorphenamide – no longer available • Triamterene and spironolactone

  22. Diagnosing Muscle Channelopathies • R/O secondary forms • Measure K+ during attack • Provocative testing for PP: seldom done! • Hypo: gluc/insulin • Hyper: K+ • Muscle Bx – vacuoles/dilated T-tubules • Electrophysiology • EMG • Short/long exercise tests • Genetics

  23. Electrophysiology: Short Exercise Test • More useful in MC • Baseline CMAP • Exercise 10 sec • Record CMAP immediately post exercise, then q 10 sec for 1 min. •  CMAP in MC and PMC • PMC exacerbated by cold • No change in CMAP in HypoKPP (Streib. Musc. Nerve. 1982; 5: 719-723) (Fournier. Ann. Neurol. 2004; 56: 650-661) (Fournier Neurology 2009)

  24. Long Exercise Test for Periodic Paralysis • Record ulnar CMAP Amp baseline • Exercise ADM 5 min • Check CMAP every 2 min. for 50 min • In PP (all types),  Amp immed post ex, over next 10-40 min, grad dec amp • In MC ↓ Amp immed post ex, rapid return to baseline • In PMC sustained ↓ Amp (McManis. Musc. Nerve. 1986; 9: 704-710) (Fournier. Ann. Neurol. 2004; 56: 650-661)

  25. References • Dr.Barohn’s presentation on “Muscle Channelopathies” • Anthony A.Amato and James A.Russell; Non dystrophic myotonias and periodic paralysis.Neuromuscular disorders 2008, McGraw Hill, Section II Chapter 29; 655-680 • Burge JA, Hanna MG. Novel insights into the pathomechanisms of skeletal muscle channelopathies;CurrNeurolNeurosci Rep. 2012 Feb Vol 12:62-69 • Hanna, Dipa L Raja Rayan and Michael G. Skeletal Muscle Channelopathies:Non Dystrophic Myotonias and Periodic Paralysis. Current Opinion in Neurology, 2010 Vol. 23: 466-476 • neuromuscular.wustl.edu • Doreen Fialho and Michael G.Hanna. Periodic paralysis, Handbook of Clinical Neurology, 2007 Vol. 86 (3rd series), p 89-90

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