Day 1 - Motor Neuron Diseases Flashcards
Definition of MND & ALS
Disease of UMN (Corticospinal & Corticobulbar tracts) and LMN (Anterior horn cells):
LMN “amyotrophic”
Muscle denervation result in weakness, atrophy, and fasciculations
UMN “lateral sclerosis”
Lateral corticospinal tracts sclerosis result in hyperreflexia and spasticity
It is a “progressive neurodegenerative disorder” that causes muscle weakness, disability, and eventually death.
Classification of Motor Neuron Diseases
- UMN
- Progressive Lateral Sclerosis (PLS)
- Hereditary spastic paraplegia (HSP)
- Mix
- Amyotrophic lateral sclerosis (ALS)
- LMN
- Spinal Muscle Atrophy
- Poliomyelitis, postpolio syndrome
- ALS Variants:
- Progressive Muscle Atrophy (PMA)
- Progressive Bulbar Palsy (PSP)
- Brachial amyotrophic diplegia (BAD)
- Leg Amyotrophic Diplegia (LAD)
Which is the best prognosis? worst prognosis?
Progressive muscle atrophy is best
Progressive bulbar palsy is worst
High mortality rate in MND is due to
- Pneumonia
- Respiratory failure 3-5 years (improve with ventilation & PEG tube)
Lower Versus Upper Motor Neuron Signs
LMN
- Look → Atrophy, Fasciculations, Muscle cramps
- Feel → Flaccidity
- Move → Weakness, Hyporeflexia
UMN
- Look → Atrophy (long term)
- Feel → Spasticity
- Move → Weakness, Hyperreflexia, Upgoing plantar response
- Spasticity, brisk reflexes → Loss skill in fine movements (dexterity)
What is affected and spared in NMD
Affected
- Bulbar muscles → swallowing, speech, breathing
- Cervical → Upper limb weakness
- Thoracic → Respiratory and spine stabilization
- Lumbar → Paraparesis
Spared
- Sensation
- Cerebellar
- Extraocular muscles
- Bowel and bladder
List 4 risk factors for pneumonia in MND
- Sialorrhea
- Aspiration
- Impaired clearance of mucus
- Atelectasis
EDX Result in MND
NCS
- Sensory Study: Typically normal
- Motor Study: Abnormal (Motor disease)
EMG
- Abnormal Activity: FIBs, PSWs, Fasciculations (De-innervation)
- Decreased MUP recruitment (Damaged motor neurons)
- Large amplitude MUAP (Re-innervation, its chronic disease)
SFEMG
- Abnormal fiber density, jitter, and blocking. (Mimics NMJ)
List 4 DDx for ALS
- MG
- MS
- Multifocal motor neuropathy
- ALS Variants
- Inclusion Body Myositis (IBM)
How to manage scoliosis in MND? When to interfere?
Preventive
- Good wheelchair seating system (avoid sling)
- CTLSO for apex above T8 & TLSO for apex below.
Surgical correction
- Degree > 40 degrees
- FVC < 50%
Spinal muscular atrophy type 1 (Acute infantile)
Coarse: 3–6 months, death by 2–3 years due to respiratory failure.
Affected (Bulbar, Thoracic, UL, LL)
- Bulbar: Difficulty feeding, Weak cry, Tongue fasciculations
- Thoracic: Floppy baby/hypotonia, Paradoxical breathing, Never sits independently
- LL: Frog-legged position
- Absent MSR
Normal in MND (Face & BBS)
- Extraocular muscles
- Facial Muscles
- Sphincter Muscle
Spinal muscular atrophy type 2 (Chronic infantile)
Coarse: 2–12 months, wheelchair by 2–3 years of age and death by 10 years old
Examination
- Bulbar: ± Tongue fasciculations
- Thoracic: Floppy baby/hypotonia, Progressive pulmonary involvement, Kyphoscoliosis, Independent sitting, Assistive devices for standing and walking
- Limbs: Gradual progressive limb weakness, Equinus deformity of the feet
- Absent MSR
Spinal muscular atrophy type 3 (Chronic juvenile)
Coarse: 2-15 years old, wheelchair by 30 years of age with normal life expectancy.
Clinical presentation:
- Normal intelligence
- Bulbar ± Dysphagia ± Dysarthria, Tongue fasciculations
- Thoracic: Independent standing/walking
- Limbs
- Symmetric weakness: Lower > upper, ± Gowers’ sign
- ± Calf pseudohypertrophy
- Abnormal MSR
List 4 Workups for SMA, or any MND.
- Genetic testing (Confirm diagnosis)
- Blood: Increase CPK levels (muscle break down)
- Muscle Biopsy: Hyper/atrophic fibers
- NCS
- SNAP: Normal
- CMAP: ± Abnormal
- EMG in MND
- Abnormal Activities: Fibs, PSWs, CRDs (de-innervation)
- Delayed recruitment (Weak MND)
- Short duration, small amplitude (de-innervation)
- Long duration, large amplitude (re-innervation)
Poliomyelitis vs Post Polio & Prognosis.
Poliomyelitis
Picornavirus (Poliovirus, Enterovirus) orally enters the body and spreads via lymphoid system leading to degeneration and inflammation of the anterior horn cell
Post-Polio Syndrome
Resolution of inflammatory damage to motor neurons from viral infection.
Reinnervation of denerved muscle fibers by collateral sprouting.
Later on loss of the anterior horn cell from aging and increased metabolic demand
Prognosis
25%: Severe disability
25%: Mild disability
50%: Complete recovery
Clinical presentation of poliomyelitis.
Remember its MND (bulbar, thoracic, limbs) after viral infection.
1- Viral infection
Fever, malaise, sore throat, vomiting, headache, back and neck pain, and stiffness.
2- Bulbar: Dysphasia, nasal voice, OSA
3- Weak lower limb, genu recurvatum, equines
4- Weak upper limbs, poor hand dexterity and overhead activities
5- Absent MSR
6- Autonomic dysfunction can occur (Virus affecting BBS)
Post Polio Syndrome and Rehabilitation
Diagnostic Criteria for PPS:
- Previous confirm diagnosis of paralytic poliomyelitis
- Partial or complete neurologic and functional recovery
- Stability for approximately 15 years
- Abrupt or gradual onset of new weakness and fatigue
- No other medical problems to explain new symptoms
Rehabilitation
- Assistive devices
- Energy conservation
- Avoid fatigue
- Psychological counseling
