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Proximal Muscle Weakness Myopathy Or Myositis

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					Proximal Muscle Weakness
Myopathy Or Myositis

The Case
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53 yo male, lives in boarding house Readmitted after recent discharge with c/o myalgias, weakness and falls PMHx
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COPD – many admissions, more so this year, usually treated with steroids, bronchodilators and antibiotics, still smokes

The Case
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PMHx cont’d
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PE – 2002, now on Coumadin Nephrolithiasis – 2000 Depression, remote appendectomy, Baker’s cystectomy No CAD, DM, HTN, stroke No Fam Hx of CTD, vasculitis, cancers Denies EtOH, or drugs, unprotected sex 6/12 ago

The Case
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Meds
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Ventolin/ Atrovent/ Flovent Theodur Prednisone 50 po OD Losec, Clonazepam, Wellbutrin, Coumadin, Prozac NKDA

The Case
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HPI
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Since Dec 2002, 4 admissions for AECB (2 at SMH) Treated with steroids each time Recent admission April 26 to May 10
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First 60 mg IV solumedrol then po then stopped but flared so restarted on 50 Prednisone and tapered to off 3 days post discharge (total 17 days)

The Case
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HPI cont…
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In hospital – no myalgias, weakness, unsteadiness On discharge – able to do all activities, limited by SOB Approx 3/7 post D/C felt “achy” in thighs then shoulders associated with tremor in upper extremities

The Case
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HPI cont…
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Became progressively weaker over next week – unable to stand from toilet seat, get up from bed, but able to walk Started to fall, legs gave out, no presyncope, vertigo, LOC Up to 3 times a day, so came to ER Felt to also have AECB so started on steroids

The Case
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HPI cont…
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Denies focal weakness, sensory deficit, dysphagia, headache, visual change No F/C/NS, rash, wt loss
VSS, afebrile, 94% on r/a Neck supple, no scalp tenderness, no LN, normal thyroid

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O/E
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The Case
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O/E cont…
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Diffuse wheezes, decreased A/E, distant but normal HS, Abdo benign No hand or heliotropic rash, no active jts, normal ROM, tender quadriceps bilaterally Obvious quadriceps atrophy Deltoid 4/5, biceps 4/5, triceps 4-/5, hands 5/5, Hip F/E 4/5, Knee F/E 4/5, Feet 5/5 Reflexes normal (? brisk), sensation normal

The Case
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Investigations
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Hg 133 (MCV 103.4), WBC 10.2, Plt 218 Lytes, Cr normal, Ca, P04, Mg normal TSH 0.3, fT4 12.4 fT3 CK 1074  1237  680  423  196  64 EMG possible polyneuropathy, no fasciculations, no myopathy detected

Why is he weak? & Why is the CK high? Neuropathy, Myopathy Or Myositis?

Neuropathy
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Pattern usually involves distal motor and sensory neurons > proximal Can be seen in anterior horn cell disease and NMJ disorders EMG shows fasciculations or amplitude loss Elevation of CK can be seen in AHC dz but not a common feature

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Based on history, physical and investigations the differential can be narrowed

Inflammatory
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Polymyositis
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Usual insidious onset (3-6/12) with no precipitant Shoulder and girdle most affected, neck in ~50%. Dysphagia and dysphonia can develop Myalgias and arthralgias not uncommon but severe tenderness and synovitis are unusual

Inflammatory
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Polymyositis
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CK is usual elevated at some point but may be normal early or with advanced atrophy EMG reveals: ^ insertional activity, spont bizarre high-frequency discharges, polyphasic MUP of low amplitude 10-15% have normal EMGs Biopsy – necrosis and regeneration with T cell infiltrate

Inflammatory
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Polymyositis
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Associated with auto-antibodies to aminoacyl-tRNA synthetases (anti-Jo-1) Mainstay of treatment is steroids – initial Prednisone @ 0.5-1.5mg/kg/day MTX and Imuran also affective Associated with cancer – 6-fold with DM (15%) and 2-fold with PM (9%)

Inflammatory
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Inclusion body myositis
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Affects older ages (mean 60yo) Symptoms present for 5-6yrs prior to Dx Proximal lower ext usually prior to upper Usually symmetric but asymmetric in 1015%. Myalgias in ~40% CK normal or mildly elevated (<10X norm) EMG similar to PM, may have nerve changes

Inflammatory
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Inclusion body myositis
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MRI can help - involvement of the deep finger flexors occurs early in the course of the disease; demonstrated in almost 95% Biopsy - Basophilic-rimmed vacuoles within the muscle fiber sarcoplasm in virtually all patients; filamentous inclusions and vacuoles on electron microscopy

Inflammatory
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Inclusion body myositis
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Treatment – no good role for steroids; MTX and Imuran have little effect, small effect from IVIG

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Myositis can be a feature of SS, SLE, MCTD, Sjogrens > RA, AOSD, WG and PAN

Metabolic
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Disorders of glycogen metabolism
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McArdle’s – def of myophosphorylase Usually exercise induced, usually develop in childhood May be associated with severe cramping and rhabdo Subset with proximal muscle weakness as adults

Metabolic
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Disorders of glycogen metabolism
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Glycogen deposition on biopsy Forearm Ischemic Exercise test – venous lactate and NH3 levels pre and post tourniquet
Disorders of lipid metabolism Carnitine deficiency – proximal muscles affected with ^CK and myopathy on EMG

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Mitochondrial myopathies
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Drug-Induced
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Steroids
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May occur shortly after onset of therapy or after years Subacute over weeks with proximal muscle weakness and wasting but usually not myalgias or tenderness Dose related – rare in <10mg/day; >40-60 usually results in some weakness

Drug-Induced
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Steroids
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Glucocorticoids – direct catabolic effect on skeletal muscle via amino acid for gluconeogenesis Also interfers with ILGF-1 signaling  increased myocyte apoptosis CK usually normal; EMG usually normal With reduction or D/C of steroids, ^ strength within 3-4 weeks

Looking Back – this admission
Date 18/5/03 18 18 19 20 22 CK 792 1074 1209 1237 698 447 History ++falls Started on 50mg Pred

23
24 25

423
312 196

28

64

Myalgias gone

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MRI
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High uptake in rectus femoris bilaterally, non-specific Upper extremities normal

Did the steroids help him Or Is the CK from the falls?

Looking Back–Prev admissions
Date CK History

28/4/99
13/11/00 14

178
1937 1541

ER visit with L headache and c/p
R flank pain- renal colic +AECB started on

18
15/12/00 15/11/01 27/08/02 27 27

1420
873 120 46 54 51

50 Pred
Renal colic + SOB AECB AECB with h/a and Myalgias Pred 50 x 10/7

Looking Back–Prev admissions
Date CK History

7/11/02
7 8 8

448
555 674 872

SOB with generalized
Weakness, NX, F/C Pred with slow taper

13/12/02
24/3/03 24 26/4/03 26

152
64 80 88 57

AECB Rx steroids
AECB Rx steroids AECB Rx steroids

Is there a pattern?
Should he be biopsied?


				
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posted:4/17/2008
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