ms gayatin part 4 midterm MUSCULAR DYSTROPHY

Muscular Dystrophy (MD)

think of it as a "Genetic Glitch" in the body's construction crew. Usually, our body uses a protein called dystrophin to keep muscle cells strong. In —, that protein is missing or broken, causing muscles to "waste away" (atrophy) over time.

1. It’s Genetic: You are born with the instructions for it; it’s not something you "catch."

2. It’s Progressive: It starts with weakness and gets worse over time.

3. Voluntary vs. Involuntary: It mainly hits the muscles you control (arms/legs), but can eventually hit the ones you don't (heart/lungs).

Muscular Dystrophy (MD) The "Big Three" Facts to Remember

DUCHENNE

MUSCULAR DYSTROPHY TYPE

Symptoms include general muscle weakness and wasting; affects pelvis, upper arms, and upper legs; eventually involves all voluntary muscles; survival beyond 20s is rare. Seen in boys only. Very rarely can affect woman, who have much milder symptoms and a better prognosis.

Congenital

MUSCULAR DYSTROPHY TYPE

Symptoms include general muscle weakness and possible joint deformities; disease progresses slowly; shortened life span.

BECKER

MUSCULAR DYSTROPHY TYPE

Symptoms are almost identical to Duchenne, but less severe; progresses more slowly than Duchenne; survival into middle age. As with Duchenne, disease is almost always limited to males.

EMERY-DREIFUSS

MUSCULAR DYSTROPHY TYPE

Symptoms include weakness and wasting of muscles of the hands, forearms, and lower legs; progression is slow; rarely leads to total incapacity

LIMB-GIRDLE

MUSCULAR DYSTROPHY TYPE

Symptoms include weakness and wasting, affecting shoulder girdle and pelvic girdle first; progression is slow; death is usually due to cardiopulmonary complications.

MYOTONIC

MUSCULAR DYSTROPHY TYPE

Symptoms include weakness of all muscle groups accompanied by delayed relaxation of muscles after contraction; affects face, feet, hands, and neck first; progression is slow, sometimes spanning 50 to 60 years.

FACIOSCAPULOHUMERAL

MUSCULAR DYSTROPHY TYPE

Symptoms include facial muscle weakness and weakness with some wasting of shoulders and upper arms; progression is slow with periods of rapid deterioration; life span may be many decades after onset.

DISTAL

MUSCULAR DYSTROPHY TYPE

Symptoms include weakness and wasting of muscles of the hands, forearms, and lower legs; progression is slow; rarely leads to total incapacity.

OCULOPHARYNGEAL

MUSCULAR DYSTROPHY TYPE

Symptoms affect muscles of eyelids and throat causing weakening of throat muscles, which, in time, causes inability to swallow and emaciation from lack of food; progression is slow.

2–6 years (Toddlers)

DUCHENNE AGE AT ONSET

adolescence to early adulthood

AGE AT ONSET BECKER

birth

AGE AT ONSET CONGENITAL

40 to 60 years

AGE AT ONSET DISTAL

childhood to early teens

AGE AT ONSET EMERY-DREIFUSS

childhood to early adults

AGE AT ONSET FACIOSCAPULOHUMERAL

late childhood to middle age

AGE AT ONSET LIMB-GIRDLE

20 to 40 years

AGE AT ONSET MYOTONIC

40 to 70 years

AGE AT ONSET OCULOPHARYNGEAL

Step	What's Happening?	Simple Analogy
Genetic Defect	Xp21.2 Deletion	A missing page in the blueprint.
No Dystrophin	The "Anchor" is missing	The walls are no longer attached to the floor.
Mitochondria Swell	Water enters/Calcium fails	The power plant floods and explodes.
Fibrosis/Fat	Scarring replaces muscle	Fixing a brick wall with bubblegum and tape.
Outcome	Loss of strength/elasticity	The "building" (body) eventually collapses.

Muscular Dystrophy

The "Big" Calf Lie (Pseudohypertrophy)

• The Look: The calves (Gastrocnemius) look huge and muscular, like an athlete's.

• The Reality: It’s a "False" (Pseudo) enlargement. The actual muscle has been replaced by fat and scar tissue.

• Memory Hook: It’s like a balloon filled with sand instead of air—it looks big, but it’s heavy and doesn’t "bounce" or flex.

The "Human Ladder" (Gower’s Sign)

• The Action: To stand up from the floor, the patient has to "walk" their hands up their own legs.

• The Reason: Their Gluteus Maximus (butt) and Quadriceps (thighs) are too weak to lift their torso.

• Memory Hook: = Ground to Standing. They use their arms because their legs can't do the heavy lifting.

(Trendelenburg Sign)

• The Action: When walking, the pelvis drops on the side of the lifted leg, causing a swaying or "waddling" gait.

• The Reason: Hip stabilizer muscles are weak.

• Memory Hook: = Tilt. The hips tilt because they lack the "strength" to stay level.

(Lumbar Lordosis)

• The Look: An exaggerated inward curve of the lower back (swayback).

• The Reason: To keep from falling over due to gluteal weakness, the patient shifts their center of gravity forward.

• Memory Hook: = Lumbar curve. The back bends to balance the weak bottom.

🔨 5. The "Reflex Check" (Deep Tendon Reflexes)

• The Finding: Reflexes (like the knee-jerk) are STILL PRESENT.

• Why it matters: This helps doctors tell MD apart from Spinal Muscular Atrophy (SMA). In SMA (a nerve issue), reflexes disappear. In MD (a muscle issue), the "wires" (nerves) still work, so the reflex is there until the muscle is totally gone.

Sign	What you see	Why it happens
Pseudohypertrophy	Fat Calves	Fat/Scar tissue replaces muscle.
Gower's Sign	"Walking" up legs	Weak Thighs/Glutes (Quads).
Lordosis	Arched lower back	Compensating for weak Glutes.
Trendelenburg	Swaying/Waddling	Weak Hip Stabilizers.
DTRs	Reflexes present	Proves it's a Muscle (not Nerve) problem.

summary findings

🧪 1. The Blood Test: CPK (Creatine Phosphokinase)

• What it is: An enzyme normally kept inside healthy muscle cells to help with energy.

• The Finding: Massively Elevated ($10$ to $200 \times$ normal).

• Why? Because the cell membrane is "leaky" (remember the missing Dystrophin anchor?), the CPK "spills" out into the blood.

The Gold Standard: Muscle Biopsy

They take a tiny piece of muscle and look at it under a microscope.

• Staining: They use a special dye to look for Dystrophin. In MD, it will be absent.

• Infiltration: You’ll see "imposter" tissue—connective (fibrous) tissue and fat—taking over.

• Necrosis: You’ll see foci of necrosis (spots where muscle cells have actually died).

Gold Standard lab test

The Definitive Proof: DNA Testing

• The Finding: This looks at the "blueprint" (the Xp21.2 gene) and confirms the deletion or mutation.

• Significance: This is the most accurate way to confirm which type of MD the patient has and helps with family genetic counseling.

The "Electric" Test: EMG (Electromyography)

This test uses tiny needles to listen to the electrical activity of the muscles.

• The Finding: Myopathic pattern.

• What that looks like: * Decreased Amplitude: The electrical "spikes" are small (weak signal).

  • Short Duration: The muscle contraction doesn't last long.

  • Polyphasic: The signal looks "messy" or "jagged" because the muscle fibers aren't firing together in a clean wave.

• Memory Hook: The "wiring" (nerves) is fine, but the "lightbulb" (muscle) is flickering and weak.

Strategy	Specific Tool	Why do we do it?
Pharmacology	Glucocorticoids	Delay loss of walking and strengthen heart/lungs.
Respiratory	Abdominal Thrusts	Clear mucus to prevent Pneumonia.
Respiratory	Peak Flow < 160	Signal that the patient needs help coughing.
Mobility	KAFO Braces	Keep the child standing/walking for as long as possible.
Maintenance	ROM Exercises	Prevent painful muscle contractures (stiffness).

Summary Management Table