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PassPMR - 04 Electrodiagnostic Medicine > 8 - Myopathies > Flashcards

8 - Myopathies Flashcards

1
Q

Draw Sarcomere (6 marks) 🔑🔑

A
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2
Q

The Role of Dystrophin. 🔑🔑

A

Dystrophin

  • Protein found in the sarcolemma (plasma membrane of the muscle cell) of normal muscle to provide support and structural integrity for the muscle membrane.
  • Dystrophin dysfunction leads to muscle fiber necrosis, myalgia, fatigue, and weakness.
  • Muscle biopsies help differentiate between dystrophinopathies.

Duchenne muscular dystrophy

  • Dystrophin is absent or markedly deficient.

Becker’s muscular dystrophy

  • Abnormalities are less severe.

Cuccurollo 4th Edition Chapter 5 EDX pg438

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3
Q

List 6 Etiology of Myopathies

A
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4
Q

Myopathies: PEx - EDX - Investigations 🔑🔑

A

💡 Hallmark sign of myopathy is the inability to generate a forceful contraction

PHYSICAL EXAMINATION

  1. Sensory
    • Normal sensation
  2. Motor
    • Symmetric proximal muscle weakness, including neck and facial muscles
    • Atrophy, malaise & fatigue
    • Myotonia
    • Gait disturbance (Waddling gait, Gowers’ sign, Foot Drop)
  3. Reflexes
    • Hyporeflexia
  4. Review of System
    • Cardio: Palpitations, arrhythmia, syncope (conduction heart block)
    • Resp: Dyspnea, orthopnea, nocturnal hypoventilation

EDX

  1. Normal NCS
  2. EMG Myopathic pattern: low amplitude polyphasic potentials

INVESTIGATIONS

  • Elevated serum CK
  • Muscle biopsy : muscle fiber necrosis and regeneration

Cuccurollo 4th Edition Chpater 5 EDX pg438

DeLisa 5th edition Chapter 30 Myopathy pg759-760

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5
Q

How does symptom onset aids in diagnosis of myopathy?🔑🔑

A

Weakness over hours: toxic etiology or periodic paralyses

Weakness over days: acute dermatomyositis (fever, skin) or rhabdomyolysis (urine)

Weakness over a weeks: polymyositis, steroid myopathy, endocrine (hypo/hyperthyroidism)

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6
Q

List 2 DDx for myopathy.🔑🔑

A

Myopathies can mimic NMJ in EMG (myopathic pattern)

  1. Myasthenia Gravis
  2. Lambert-Eaton Myasthenic Syndrome (LEMS)
  3. Guillain-Barre Syndrome (GBS)
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7
Q

Hallmark of myopathy in physical examination.🔑🔑

A

Inability to generate a forceful contraction

Myopathy: any disease that affects the muscles that control voluntary movement in the body.

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8
Q

Define myotonia & List 4 DDx Myotonia 🔑🔑

A

Myotonia

  • Painless delayed relaxation of skeletal muscles following a voluntary contraction.
  • Can be elicited by percussion, cold and relieved with exercise.

DDx

  1. Myotonia congenita (born with it)
  2. Neuromyotonia (peripheral nerve hyperexcitability)
  3. Hyperkalemic periodic paralysis (K+ disorders)
  4. Hypokalemic periodic paralysis (K+ disorders)
  5. Myotonic dystrophy (muscle problem)
  6. Hypothyroid myopathy
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9
Q

List 2 Best investigation to confirm diagnosis and type of myopathy.🔑🔑

What are the 3 most valuable tests for evaluating patients with suspected muscle disease?

A

ANSWER 1

  1. Muscle biopsy
  2. Genetic testing.
  3. Elevated CK in Blood.

ANSWER 2

  1. Serum CK levels
  2. Electromyography (EMG)
  3. Muscle biopsy

Neurology Secrets 6th Edition Chapter 4 Myopathy pg50

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10
Q

Myopathy with Type 1 vs Type 2 fiber atrophy. 🔑🔑

A

Type 1 Line of water

  • Myotonic dystrophy
  • Nemaline rod myopathy
  • Fiber type disproportion

Type 2 Gym

  • Steroid myopathy
  • Deconditioning
  • Myasthenia gravis

Cuccurollo 4th Edition Chapter 5 EDX pg439

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11
Q

What is Gower’s sign? 🔑🔑

A

Gower’s sign

Maneuver of rising from a supine position in the presence of marked proximal weakness.

In order to rise to standing:

  1. The patient rolls to a prone position
  2. Pushes off the floor
  3. Locks the knees
  4. Pushes the upper body upward by “climbing up” the legs with the hands.

Neurology Secrets 6th Edition Chapter 4 Myopathies

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12
Q

Which myopathies are considered painful? 🔑🔑

A

Myopathies that may be associated with pain include

  1. Inflammatory myopathies
  2. Metabolic myopathies
  3. Mitochondrial myopathies
  4. Muscular dystrophies (limb-girdle, Becker muscular dystrophy [BMD]).

Neurology Secrets 6th Edition Chapter 4 Myopathies

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13
Q

Which myopathies are characterized by predominant distal weakness? 🔑🔑

A

Myopathies with distal weakness

  1. Myotonic dystrophy
  2. Facioscapulohumeral dystrophy
  3. Inflammatory myopathies: IBM
  4. Metabolic myopathy
  5. Congenital myopathy

Neurology Secrets 6th Edition Chapter 4 Myopathies pg64

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14
Q

Which myopathies are associated with dysphagia? 🔑🔑

A

Myopathies associated with dysphagia

  1. DMD
  2. Polymyositis
  3. Dermatomyositis
  4. IBM
  5. Myotonic dystrophy
  6. Mitochondrial Myopathy

PMR Secrets 3rd Edition Chapter 51 Myopathy pg420 Q29

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15
Q

Myopathies with Normal CK & Normal EMG 🔑🔑

A

Normal CK: LGMD, FSHD, Metabolic, IMB

Normal EMG: Early mild, Metabolic, Steroid

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16
Q

All myopathies are symmetrical except? 🔑🔑

A
  1. Inclusion body myositis (IBM)
  2. Facioscapulohumeral muscular dystrophy (FSHD)
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17
Q

What conditions other than myopathies are associated with an elevated CK level? 🔑🔑

A
  1. Exercise (especially if vigorous or unaccustomed)
  2. Increased muscle bulk
  3. Muscle trauma (needle injection, EMG, surgery, seizures, edema, or contusion)
  4. Acute kidney disease
  5. Malignant hyperthermia
  6. Viral illnesses
  7. Endocrine disorders (hypo/hyperthyroid)
  8. Neurogenic disease (e.g., amyotrophic lateral sclerosis)

Neurology Secrets 6th Edition Chapter 4 Myopathies

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18
Q

Why we have early recruitment in myopathic diseases?

A

The central nervous system can increase the strength of muscle contraction by:

  1. Increasing the number of active motor units (ie, spatial recruitment)
  2. Increasing the firing rate (firing frequency) at which individual motor units fire to optimize the summated tension generated (ie, temporal recruitment)

In muscle diseases such as polymyositis or muscular dystrophies

Number of motor units are unaffected but the muscle fiber content of each motor unit is reduced (muscle fibers are damaged/diseased) → force output of each unit is diminished.

Compensation occurs by having multiple motor units begin firing simultaneously

Early recruitment in myopathic conditions

In a myopathy, isolating a single firing motor unit often is impossible. Even with minimal muscular effort, typically 2 or more units may be activated. This recruitment pattern in myopathic conditions is called “early recruitment” or “increased recruitment.”

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19
Q

Duchenne muscular dystrophy (DMD) 🔑🔑 (OSCE)

Etiology - Inheritance - Onset - Course - MSK & NON-MSK - Labs - EDX - Rehabilitation

A

Etiology

  • Duchenne always accompanied by their mothers
  • Absence of dystrophin, X-linked recessive (xp21)

Coarse

  • Starts at kindergarten 1-2, mother or teacher noticing abnormal motor development
  • 3–5 years old
  • Wheelchair by 12 years old
  • Death by 20s

Presentation

💡 Starts with: Frequent falling, Inability to jump, Decreased endurace, Inability to keep with peers, Toe walking, Inability to take stairs

  1. Possible mental retardation
  2. Extra-ocular muscles are spared
  3. Scoliosis (worsen after wheelchair / immobility due to spinal muscle disuse atrophy)
  4. Scapular winging
  5. Increased lumbar lordosis
  6. Paradoxical breathing and restrictive lung disease
  7. Proximal muscle weakness (pelvic girdle, quads wasting)
  8. Ambulation difficulties: Toe walking, clumsy running
  9. Gower’s sign: Difficulty rising from the floor due to hip and knee extensor weakness
  10. Trapezius pseudohypertrophy
  11. Calf pseudohypertrophy with fat and fibrous tissue
  12. Contractures: Iliotibial band (first), Achilles tendon
  13. Abnormal MSR

Investigation

  1. Muscle Biopsy: No dystrophin
  2. Genetic: Mutation in xp21
  3. Blood: Increased CPK and aldolase.
  4. ECG: abnormal

EDX

  • SNAP: Normal (Muscle disease)
  • CMAP: ± Decreased amplitude
  • EMG: Myopathic picture: AA (rare), Early recruitment, ± SDSA MUAP

Cuccurollo 4th Edition Chapter 5 EDX pg440 Table 5-50

Treatment

  • Prednisone 0.75 mg/kg/d
  • Follow with Osteoporosis Clinic

Rehabilitation

  1. Cataract (ophthalmology referral)
  2. Psychosocial
    • Neuropsychological evaluation/interventions
    • Individualized education programm
  3. Dysarthria
    • Delay speech or articulation difficulties
    • Speech-language pathologist
  4. Dysphagia
    • Feeding management to prevent malnutrition and aspiration pneumonia
    • Gastrostomy tube
  5. Growth chart & Weight management
    • Obesity (early)
    • Cachexia (late)
    • Follow GI & Nutritionist: constipation, GERD and gastroparesis
  6. Scoliosis
    • Xray every 6-12 months
    • Surgery (posterior spinal fusion) before the vital capacity is below 35%
  7. Cardiology referral
    • ECG → Conduction failure
    • ECHO → Heart failure
  8. Motor rehabilitation
    • Physiotherapy: Submaximal exercises, avoid fatigue
    • Occupational Therapy: Energy conservation, Equipment devices
    • Wheelchair assessment
    • Contracture prevention: ROM exercises, stretching & orthoses
  9. Orthopedics
    • Surgery for foot and Achilles tendon to improve gait in selected situations

DeLisa 5th Edition Chapter 30 Myopathy Table 30.6 & 30.8 & Others

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20
Q

Drug of choice in DMD is prednisolone, list 6 side effects. 🔑🔑

A
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21
Q

DMD.

Respiratory assessment & when do you interfere? 🔑🔑

List 2 warning signs for respiratory failure. 🔑🔑

A

Signs & Symptoms (Day & Night)

  1. Ineffective cough (PCF < 270 mL/min)
  2. Sleep apnea
  3. Nocturnal awaking
  4. Daytime somnolence
  5. Morning headache

PMR secrets p417

Assessment (Clinical > Blood > Special)

  1. Clinically: Daytime (Fatigue, Dyspnea), Nighttime (Nocturnal hypoventilation), Pulse Oximetry
  2. ABG: Hypercapnia
  3. Peak Cough Flow (PCF) >270 mL/min
  4. Maximal inspiratory pressure (MIP)
  5. Maximal expiratory pressures (MEP)

Follow Up

  1. PFT (Restrictive lung disease) every 6 months: FVC
  2. Sleep study → Nocturnal hypoventilation and sleep apnea
  3. Ensure immunizations are up-to-date: Pneumococcal vaccines and yearly inactivated influenza vaccine

Breathing Management

  1. Lung Volume Recruitment (LVR)
  2. Starting Non-Invasive Ventilation
    • FVC < 60% or PCF < 270 mL/min
    • Nighttime: Bilevel positive pressure ventilation (BiPAP) with mouthpiece
    • Daytime: BiPAP
  3. Starting Invasive Ventilation
    • Not responsive to 24-hour NIV
  4. Oxygen Therapy
    • Contraindicated in restrictive airway disease
    • Lower the respiratory drive and accumulation of CO2
    • Result in respiratory failure

Cough Management

  1. Mechanical airway clearance (CoughAssist): Prevent atelectasis and promote airway clearance

Dr. Maitham’s My Summary

22
Q

Becker muscular dystrophy (BMD) 🔑

Etiology - Inheritance - Onset - Course - Presentation - Labs - EDX - Tx

A

💡 BMD: Mild DMD, Start late and progress slow

Inheritance

  • X-linked recessive

Onset & Coarse

  • Adulthood
  • Slowly progressive

Clinical Presentation

  • Proximal weakness
  • Less mental retardation
  • Calf pseudohypertrophy

Laboratory Investigations

  • M Bx: Decreased dystrophin (15%–85%)
  • Blood: increased CPK

EDX

  • Same as DMD
  • Reduced CMAP
  • Myopathic MUAP (Early Recruitment, SDSA)

Treatment

  • Physical & Respiratory Rehabilitation
  • Tendon lengthening
  • Spinal Bracing
  • Possible scoliosis surgery

Cuccurollo 4th Edition Chapter 5 EDX pg440 Table 5-50

23
Q
A

Braddom 6th Edition Chapter 42 pg888

24
Q
A

DeLisa 5th Edition Chapter 30 pg765

25
Q

Facioscapulohumeral muscular dystrophy (FSHD) 🔑

Etiology - Inheritance - Onset - Course - Presentation - Labs - EDX - Tx List one muscle to test?

A

Inheritance

Autosomal dominant (lots of faces)

Onset & Coarse

Childhood-early adult, Spreads to other muscles

Muscle to Test

Tibialis anterior

Labs

M Bx: Scattered fiber necrosis and regeneration

EDX

  • Same as DMD
  • Reduced CMAP
  • Myopathic MUAP (SDSA, Early Recruitment)

Treatment

Rehabilitation

Cuccurollo 4th Edition Chapter 5 EDX pg440 Table 5-50

26
Q

Arthrogryposis definition (3 marks)

A

Arthrogryposis

Fixed deformity of the extremities, due to intrauterine hypo-mobility

Predisposing factors (weak or swimming)

  1. Myopathies
  2. Muscular dystrophies
  3. Oligohydramnios.
27
Q

Myotonic Dystrophy 🔑

Etiology - Inheritance - Onset - Course - Presentation - Labs - EDX 🔑🔑 - Tx

5 NON-neurologic complications?

List 2 Special features in investigations.

A

Myotonia

  • Delayed or inability to relax muscle after forceful contraction (Clinically)
  • Type I fiber atrophy with Type II hypertrophy
  • No dystrophin involvement

Inheritance

  • Autosomal dominant

Onset

  • Infant

Neurological

  1. Hatchet face (Wasting of the temporalis and masseter)
  2. Bilateral facial paralysis
  3. Shark mouth appearance
  4. Weakness: Distal > proximal
  5. Myotonia with sustained grip
  6. Possible club foot

Non-Neurological

  1. Mental retardation
  2. Poor vision (cataract)
  3. Ptosis
  4. Frontal balding
  5. Impotence
  6. Hypertrichosis
  7. Cardiac abnormalities
  8. Endocrine abnormalities (gynecomastia)

Muscle Biopsy

  1. Type I fiber atrophy with Type II hypertrophy
  2. No dystrophin involvement

EDX

  • Same as DMD
  • Decreased CMAP
  • Myopathic MUAP (Early Recruitment, SDSA)
  • Myotonia: Wax & Wane in both amplitude & frequency

Treatment

  • Rehabilitation
  • Bracing
  • Medications: procainamide, Dilantin, and quinine (PDQ).
  • May need a pacemaker
  • Myotonic discharges: Wax & Wane in both amplitude & frequency

Cuccurollo 4th Edition Chapter 5 EDX pg440 Table 5-50

28
Q

List 3 intrinsic and 3 extrinsic causes of myogenic contracture 🔑🔑

A

SKIN

  • Trauma, burns, infection, systemic sclerosis

ARTHRTOGENIC

  • Cartilage damage, infection, trauma
  • Degenerative joint disease (OA), Synovial inflammation (RA)
  • Capsular fibrosis (e.g., trauma, inflammation)
  • Immobilization

TENDON

  • Tendinitis, bursitis, ligamentous tear, and fibrosis

MUSCLE

Intrinsic

  1. Traumatic (Bleeding)
  2. Inflammatory (myositis, polymyositis)
  3. Degenerative (muscular dystrophy)
  4. Ischemic (DM, PVD, Compartment)

Extrinsic

  1. Spasticity
  2. Flaccid paralysis
  3. Mechanical/Positional
  4. Immobilization

DeLisa 5th Edition Chapter 48 Physical Inactivity pg1255 Table 48.2

29
Q

What is the cause syncope in myotonic Dystrophy

What is the cardiac condition in muscular dystrophy?🔑🔑

A

Conduction block

30
Q

Limb-girdle muscular dystrophy

What are the cardiac complications associated

What 2 tests to prove them and why? 🔑🔑

A

💡 Not just limb girdle, just any myopathy which is usually “limb girdle” distribution.

Complications: Dilated cardiomyopathy, Cardiac arrhythmia

Tests: Echocardiography (ECHO), Electrocardiograms (ECGs)

Why: to prevent premature cardiac death

31
Q

Emery–Dreifuss muscular dystrophy (EMD)

Name the mode of inheritance and three clinical features (triad)

A

Inheritance

X-linked muscular dystrophy

EDMD Triad

  1. Slowly progressive muscle weakness and wasting in a scapulo-humero-peroneal area
  2. Early contractures of the elbow, ankle, and posterior neck
  3. Cardiac conduction defects, cardiomyopathy, or both → routine EKG, 24-hour Holter .

Others

  • Difficulty with walking/running
  • Nocturnal hypoventilation, respiratory problems

Cuccurollo Chapter 10 Pediatric NMSK pg807

32
Q

List FOUR idiopathic type inflammatory myopathies 4 marks 🔑🔑

A
  1. Dermatomyositis
  2. Polymyositis
  3. Immune-mediated necrotizing myopathy
  4. Inclusion body myositis (IBM)

Neurology Secrets 6th Edition Chapter 4 Myopathies pg53

33
Q

Polymyositis (PM) & Dermatomyositis (DM) 🔑🔑

Etiology - Clinical presentation - Labs - EDX - Tx

A

Etiology

  1. Autoimmune
  2. Connective tissue disorder
  3. Infection
  4. Cancer

Polymyositis

  1. Neck flexion weakness
  2. Myalgias, dysphagia, dysphonia
  3. Symmetrical proximal weakness: Hips followed by shoulders

Labs

  1. Blood: Increased CPK, ESR, LDH, aldolase, SGOT, SGPT.
  2. Muscle Biopsy: Necrosis of the Type I and II fibers & Perifascicular atrophy

EMG = Myopathy = NMJ

  1. Abnormal resting activities (Fibs, PSWs, CRDs) → De-innervation due to inflammation
  2. Early and increased recruitment (more motor units are recruited to generate same force)
  3. Short-duration, polyphasic, low-amplitude MUAPs (Myopathic MUAP)

Treatment

  1. Rehabilitation
  2. Corticosteroids
  3. Cytotoxic agents
  4. IV Ig
  5. Plasmapheresis
  6. Rest.
  7. Hydroxycholoroquine for skin manifestations (dermatomyositis)

Cuccurollo 4th Edition Chapter 5 EDX pg441 Table 5-51

34
Q

List 4 skin findings in Dermatomyositis (DM) 🔑🔑 EXAM

A
  1. Heliotrope eyelid rash
  2. Malar Rash
  3. Shawl Sign
  4. Guttron’s Papules

Cuccurollo 4th Edition Chapter 5 EDX pg441 Table 5-51

Others

  1. V Sign
  2. Raynaud Phenomena
35
Q

How are Polymyositis (PM) & Dermatomyositis (DM) treated?

A

First-line treatment

Corticosteroids starting with 1 mg/kg/day

Followed by a taper 4 weeks to several months after initiation.

Second-line agent

Intravenous immunoglobulin (IVIG), azathioprine (Imuran), or methotrexate (chemotherapy).

Others

Mycophenolate mofetil (CellCept), tacrolimus, rituximab (anti-CD20 monoclonal antibody), cyclosporine (Anti-T cells), and cyclophosphamide

Neurology Secrets 6th Edition Chapter 4 Myopathies pg54

36
Q

PM and DM also have been associated with malignancies 🔑🔑

A
  1. Lung
  2. Breast
  3. GI
  4. Ovarian cancers

Neurology Secrets 6th Edition Chapter 4 Myopathies pg53

37
Q

If u have dermatomyositis (DM) patient and started on steroids but weakness worsening What could be the cause?

A

Medication

  • Steroid induced myopathy
  • Dose of steroids not sufficient

Disease

  • Wrong diagnosis
  • 10% of PM non responsive to steroids
  • Myositis worsening

Patient

  • Disuse atrophy
38
Q

Mortality in dermatomyositis (DM)

A
  1. Cardio : Congestive Heart Failure
  2. Resp : Aspiration or Interstitial Lung Disease
  3. Cancer : Malignancy
  4. Infection : MTX result in TB, Sepsis

https://www.researchgate.net/figure/Dermatomyositis-and-causes-of-death_fig6_265345352

39
Q

Inclusion Body Myositis (IBM)

Etiology - Clinical presentation - Labs - EDX - Tx

A

Etiology

  • Unknown

Presentation

  1. Painless weakness in proximal and distal muscles
  2. Asymmetric, slowly progressive
  3. Associated with a polyneuropathy

Labs

  • Blood: Increase in CK
  • Muscle Biopsy: Rimmed or cytoplasmic/basophilic vacuoles. Eosinophilic inclusion bodies

NCS → we have polyneuropathy

  • SNAP: ± Abnormal
  • CMAP: ± Abnormal

EMG = Myopathic = NMJ

  • Same as PM/DM & DMD & NMJ
  • Abnormal Activity (Fibs, PSW), Early Recruitment, SDSA Myopathic MUAP

Managment

  • Rehabilitation
  • Refractory to steroid treatment.

Cuccurollo 4th Edition Chapter 5 EDX pg441 Table 5-51

40
Q

List 2 features of IBM not found in PM and DM 🔑🔑

A
  1. Asymmetrical proximal and distal weakness
  2. Associated with polyneuropathy (Abnormal NCS)
41
Q

Hyperkalemic vs Hypokalemic periodic paralysis

Etiology - Onset - Clinical presentation & Aggravation - Labs - EDX - Tx

A

💡 Both are Autosomal Dominant, Normal NCS

HYPERK+ PERIODIC PARALYSIS

Frozen man has shut down kidneys

  1. Metabolic acidosis
  2. Renal failure
  3. Adrenal failure
  4. Hypoaldosteronism

HYPOK+ PERIODIC PARALYSIS

Fat guy sweating and peeing

  1. Excessive potassium loss through sweat
  2. Diuretics
  3. Inadequate potassium intake
  4. Gastrointestinal or renal potassium loss
  5. Hyperaldosteronism
  6. Steroid use

Cuccurollo 4th Edition Chapter 5 EDX pg444 Table 5-54

42
Q

What are the most common myotoxic agents?

A
  1. Statin
  2. Steroid
  3. Alcohol
  4. Amiodaron
  5. Colchicine
  6. Vincristine

Neurology Secrets 6th Edition Chapter 4 Myopathies pg55

43
Q

Steroid Myopathy vs Statin Myopathy

A

Cuccurollo 4th Edition Chapter 5 EDX pg444 Table 5-56

44
Q

What is stiff-person syndrome (SPS)? Treatment?

A

Stiff-person syndrome (SPS)

Fluctuating motor disturbance characterized by persistent muscular stiffness due to coactivation of agonist and antagonist muscles with superimposed spasms.

Predominantly affects the axial and proximal limb muscles

Aggravated by emotional, somatosensory, or acoustic stimuli.

Treatment

  1. Benzodiazepines, primarily diazepam (10 to 100 mg/day)
  2. Baclofen and valproic acid also may help the symptoms.
  3. Immunomodulation by corticosteroids, plasmapheresis, or IVIG

Neurology Secrets 6th Edition Chapter 4 Myopathies pg62

45
Q

Exercise prescription for myopathy

A
  1. Progressive resistance exercise
  2. Aerobic: swimming/pool therapy, cycling (moderate intensity)
  3. Daily stretching/ROM
  4. Bracing to prevent progression of scoliosis
46
Q

Systemic inflammatory response syndrome (SIRS). List 4 findings.

A

💡 In the ICU patient, various factors including infection, trauma, surgery, chemical exposure, and sepsis can lead to systemic inflammatory response syndrome (SIRS)

Inflammation with abnormal vitals

  1. White blood cell (WBC) >12,000 or <4,000,
  2. Body temperature >38°C or <36°C
  3. Heart rate >90 bpm
  4. Tachypnea:

Respiratory rate >20 breaths per minute

Hypocapnea PaCO2 <32 torr (<4.3 KPa)

Cuccurollo 4th Edition Chapter 5 EDX pg450

47
Q

Critical-illness polyneuropathy

Definition - Etiology - Incidence - PEx - EDX - Tx - Recovery

A

Definition

Degeneration of neural tissue due to multiple medical complications

Primarily axonal as well as demyelinating motor and sensory peripheral polyneuropathy

Etiology

Systemic inflammatory response syndrome (SIRS)

Incidence

  • Up to 50% of adult ICU patients
  • Higher risk: lengthy mechanical ventilation, sepsis, or multiorgan failure.

PEx

  • Difficulty in weaning the patient from the ventilator as a result of respiratory muscle weakness.
  • Polyneuropathy → LMN: Limb weakness, sensory loss, and depressed reflexes.

Labs

  • Serum CK: normal
  • Muscle biopsy: denervation atrophy (polyneuropathy)

NCS

  • Axonal polyneuropathy → we have clinical weakness

EMG

  • Abnormal Activities (denervation/reinnervation) in acute stage
  • Decreased recruitment → we have clinical weakness

Treatment

  1. Antiseptic prophylaxis
  2. Improved glycemic control
  3. Aggressive treatment of sepsis
  4. Supportive care

Recovery

  • Slow and often incomplete, even after 1 to 2 years

DDx for CIP

  • Spinal cord compression
  • Motor Neuron Disease
  • Guillain–Barre syndrome
  • Myasthenia gravis & myasthenic syndrome

Neurology Secrets 6th Edition Chapter 6 Peripheral Neuropathy pg91

Cuccurollo 4th Edition Chapter 5 EDX pg450

Braddom 6th Edition Chapter 42 Myopathic Disorders pg910

48
Q

Mention 4 DDx for ICU-related weakness. 🔑🔑

A
  1. Sepsis
    1. Septic Encephalopathy
    2. Critical illness polyneuropathy (CIP)
  2. Medications (steroid)
    1. Critical illness myopathy (CIM)
  3. Muscles
    1. Rhabdomyolysis necrotizing myopathy
    2. Disuse myopathy
49
Q

Critical-illness Myopathy 🔑

Etiology - Criteria 🔑🔑 - Incidence - PEx - EDX - Tx - Recovery - DDx

A

Etiology

Inflammatory myopathy due to multiple medical complications causing muscle membrane instability and muscle cell breakdown

Criteria → Clinical + EDX (Gold standard)

  • Critically ill patient with limb weakness (Flaccid paralysis)
  • Difficulty weaning off of the vent (Respiratory weakness)
  • Sensory NCS: Normal SNAP (myopathy)
  • Motor NCS: Abnormal CMAP amplitude <80% of normal value

PEx

  • Respiratory weakness
  • Flaccid limbs

Labs

  • Serum CK: mild elevation
  • Biopsy: loss of thick filaments (myopathy)

EMG = Myopathy

  • Active denervation (early)
  • Early recruitment (myopathy)
  • Small, short, polyphasic MUAPs (Myopathic MUAP)

Treatment

  1. Decreasing corticosteroids
  2. Eliminating neuromuscular blocking agents
  3. Early rehabilitation and mobilization
  4. Electrical stimulation (FES or NMES)

Braddom 6th Edition Chapter 42 Myopathic Disorders pg910

Cuccurollo 4th Edition Chapter 5 EDX pg450

Neurology Secrets 6th Edition Chapter 19 Neurocritical Care Table 19-14

50
Q

Mention 5 Critical Illness Myopathies 🔑🔑

A

Critical Illness Myopathies

  1. Diffuse cachectic myopathy
  2. Rhabdomyolysis
  3. Thick filament myopathy
  4. Acute myopathy with scattered necrosis
  5. Acute myopathy with diffuse necrosis

Braddom 6th Edition Chapter 42 Myopathic Disorders pg910

PassPMR - 04 Electrodiagnostic Medicine (8 decks)

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