8 - Myopathies

Question 1

Draw Sarcomere (6 marks) 🔑🔑

Answer 1

Question 2

The Role of Dystrophin. 🔑🔑

Answer 2

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

Question 3

List 6 Etiology of Myopathies

Answer 3

Question 4

Myopathies: PEx - EDX - Investigations 🔑🔑

Answer 4

💡 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

Question 5

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

Answer 5

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)

Question 6

List 2 DDx for myopathy.🔑🔑

Answer 6

Myopathies can mimic NMJ in EMG (myopathic pattern)

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

Question 7

Hallmark of myopathy in physical examination.🔑🔑

Answer 7

Inability to generate a forceful contraction

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

Question 8

Define myotonia & List 4 DDx Myotonia 🔑🔑

Answer 8

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

Question 9

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?

Answer 9

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

Question 10

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

Answer 10

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

Question 11

What is Gower’s sign? 🔑🔑

Answer 11

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

Question 12

Which myopathies are considered painful? 🔑🔑

Answer 12

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

Question 13

Which myopathies are characterized by predominant distal weakness? 🔑🔑

Answer 13

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

Question 14

Which myopathies are associated with dysphagia? 🔑🔑

Answer 14

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

Question 15

Myopathies with Normal CK & Normal EMG 🔑🔑

Answer 15

Normal CK: LGMD, FSHD, Metabolic, IMB

Normal EMG: Early mild, Metabolic, Steroid

Question 16

All myopathies are symmetrical except? 🔑🔑

Answer 16

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

Question 17

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

Answer 17

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

Question 18

Why we have early recruitment in myopathic diseases?

Answer 18

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.”

Question 19

Duchenne muscular dystrophy (DMD) 🔑🔑 (OSCE)

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

Answer 19

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

Question 20

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

Answer 20

Question 21

DMD.

Respiratory assessment & when do you interfere? 🔑🔑

List 2 warning signs for respiratory failure. 🔑🔑

Answer 21

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

Question 22

Becker muscular dystrophy (BMD) 🔑

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

Answer 22

💡 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

Question 23

Answer 23

Braddom 6th Edition Chapter 42 pg888

Question 24

Answer 24

DeLisa 5th Edition Chapter 30 pg765

Question 25

Facioscapulohumeral muscular dystrophy (FSHD) 🔑 Etiology - Inheritance - Onset - Course - Presentation - Labs - EDX - Tx List one muscle to test?

Answer 25

**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

Question 26

Arthrogryposis definition (3 marks)

Answer 26

**Arthrogryposis** Fixed deformity of the extremities, due to intrauterine hypo-mobility **Predisposing factors (weak or swimming)** 1. Myopathies 2. Muscular dystrophies 3. Oligohydramnios.

Question 27

Myotonic Dystrophy 🔑 Etiology - Inheritance - Onset - Course - Presentation - Labs - EDX 🔑🔑 - Tx 5 NON-neurologic complications? List 2 Special features in investigations.

Answer 27

**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

Question 28

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

Answer 28

**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

Question 29

What is the cause syncope in myotonic Dystrophy What is the cardiac condition in muscular dystrophy?🔑🔑

Answer 29

Conduction block

Question 30

Limb-girdle muscular dystrophy What are the cardiac complications associated What 2 tests to prove them and why? 🔑🔑

Answer 30

💡 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

Question 31

Emery–Dreifuss muscular dystrophy (EMD) Name the mode of inheritance and three clinical features (triad)

Answer 31

**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

Question 32

List FOUR idiopathic type inflammatory myopathies 4 marks 🔑🔑

Answer 32

1. Dermatomyositis 2. Polymyositis 3. Immune-mediated necrotizing myopathy 4. Inclusion body myositis (IBM) Neurology Secrets 6th Edition Chapter 4 Myopathies pg53

Question 33

Polymyositis (PM) & Dermatomyositis (DM) 🔑🔑 Etiology - Clinical presentation - Labs - EDX - Tx

Answer 33

**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

Question 34

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

Answer 34

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

Question 35

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

Answer 35

**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

Question 36

PM and DM also have been associated with malignancies 🔑🔑

Answer 36

1. Lung 2. Breast 3. GI 4. Ovarian cancers Neurology Secrets 6th Edition Chapter 4 Myopathies pg53

Question 37

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

Answer 37

**Medication** * Steroid induced myopathy * Dose of steroids not sufficient **Disease** * Wrong diagnosis * 10% of PM non responsive to steroids * Myositis worsening **Patient** * Disuse atrophy

Question 38

Mortality in dermatomyositis (DM)

Answer 38

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

Question 39

Inclusion Body Myositis (IBM) Etiology - Clinical presentation - Labs - EDX - Tx

Answer 39

**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

Question 40

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

Answer 40

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

Question 41

Hyperkalemic vs Hypokalemic periodic paralysis Etiology - Onset - Clinical presentation & Aggravation - Labs - EDX - Tx

Answer 41

💡 **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

Question 42

What are the most common myotoxic agents?

Answer 42

1. Statin 2. Steroid 3. Alcohol 4. Amiodaron 5. Colchicine 6. Vincristine Neurology Secrets 6th Edition Chapter 4 Myopathies pg55

Question 43

Steroid Myopathy vs Statin Myopathy

Answer 43

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

Question 44

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

Answer 44

**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

Question 45

Exercise prescription for myopathy

Answer 45

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

Question 46

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

Answer 46

💡 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

Question 47

Critical-illness polyneuropathy Definition - Etiology - Incidence - PEx - EDX - Tx - Recovery

Answer 47

**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

Question 48

Mention 4 DDx for ICU-related weakness. 🔑🔑

Answer 48

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

Question 49

Critical-illness Myopathy 🔑 Etiology - Criteria 🔑🔑 - Incidence - PEx - EDX - Tx - Recovery - DDx

Answer 49

**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

Question 50

Mention 5 Critical Illness Myopathies 🔑🔑

Answer 50

**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