Functional recovery takes weeks to months

NMD continued Flashcards by Mikayla Mischuk

GBS presentation

Wide range of clinical findings
* Different degrees of involvement of motor, sensory and autonomic
fibres
* Different locations – spinal roots, cranial nerves, peripheral nerves
* Classic sensorimotor GBS (AIDP) is the most common - ~90% of cases
* ~10 days after antecedent event the earliest symptom is distal
paresthesia and low back pain (nerve root inflammation)

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GBS presentation / development

Earliest symptoms distal paresthesia & low back pain (nerve root
inflammation)
~10 days after antecedent event
Progressive, symmetric weakness - both proximal and distal muscles
Proximal due to nerve roots
Distal due to peripheral nerves
Commonly an ‘ascending pattern’ of weakness
legs earlier and weaker than arms
Hyporeflexia or areflexia in 90%
Cranial nerve involvement (facial > oropharyngeal > extraocular muscles)

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GBS - other complications

Other complications:
* Respiratory muscle weakness, particularly diaphragm
* 10-30% need ventilator support
* Autonomic dysfunction in 2/3 of patients
* Cardiac arrhythmias
* Labile blood pressure
* Orthostatic hypotension
* Abnormal sweating
* GI dysmotility (can lead to ileus and bowel rupture)
* GU dysfunction

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GBS investigations

CSF: Cytoalbuminological Dissociation
* High protein, normal cells

Nerve Conduction Studies
* Demyelination (or axonal) damage
* Can be delayed up to 14 days from symptom onset

MRI – enhancement of spinal nerve roots
* Antibody testing
* Campylobacter infection

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GBS tx

immunotherapy
* IVIG or Plasma exchange
* Remove autoantibodies
* Stop inflammatory response
* But do not reverse degree of nerve damage
* When started w/in 2 wks (IVIG) and 4 wks (PLEX) of onset of
weakness:
* reduce the time it takes for recovery

*repeating IVIg or plasma exchange if no response after initial tx will not benefit

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GBS - supportive care

may need ICU if - dysautonomia, bulbar dysfunction, severe or worsening weakness, evolving resp distress

supportive care:
-DVT prophylaxis
- pain management
- bowel / bladder management
- decubitus ulcers
- fatigue
- psychiatric support
- future immunization

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GBS prognosis

Functional recovery takes weeks to months

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Hereditary Neuropathies

¡ Often Slow evolution, starting
in childhood or early adulthood
¡ Motor, sensory & autonomic
varieties identified
¡ Most are rare
¡ Most common type is “Charcot
Marie Tooth” neuropathy (high arches)
¡ Some with known genetic loci

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motor neuron diseases

A group of conditions
characterized by injury to
lower motor neurons
(LMNs), upper motor
neurons (UMNs) or both
Affect the cell body of the
motor neuron, thus
considered
‘neuronopathies’ rather
than neuropathies

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Amyotrophic Lateral Sclerosis

Incidence 2 per 100,000 people per year
Prevalence 5 per 100,000 people
1.5 Men : 1 women
Most commonly presents between 60 and 75 years
Risk factors:
Age
Family history
Cigarette smoking
Other possible risk factors:
High levels of physical activity
Heavy metals
Toxins (pesticides)
Military service

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ALS clinical features

Most common: asymmetric lower limb weakness, asymmetric upper limb
weakness or bulbar manifestations
Each accounts for 25-30% of patients at presentation
Limb weakness typically begins in distal muscles
Upper limb onset
Clumsiness
Difficulty with closing buttons or opening jars
Lower limb onset
Foot drop is most common
Lack of pain or sensory symptoms
Progression into more proximal muscles is expected

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ALS - UMN vs LMN

LMN involvement
* Usually results in muscle cramps – painful and disruptive to sleep
* Fasciculations
UMN involvement
* Limb spasticity
* Slowness or stiffness of movement
* Difficulty with balance, falls
* Hyperreflexia

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ALS - bulbar manifestations

Bulbar Manifestations
* Mixed spastic-flaccid dysarthria
* Tongue atrophy and fasciculations (not really caused by other things)
* Dysphagia
* Pseudobulbar affect
* Uncontrollable and at times intrusive bouts of laughing or crying (frontal lobe pathology)

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ALS - resp manifestations

Respiratory manifestations
* Weakness of diaphragm and other respirator muscles
* Dyspnea with exertion and at rest
* Sleep disordered breathing
* Orthopnea
* Weak cough, can’t clear secretions
* Shortness of breath with speaking

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ALS - cognitive manifestations

Cognitive manifestations
* 50% of patients will have cognitive or behavioural dysfunction
* 15% will develop frontotemporal dementia
* Prognosis
* Between 17 and 90 months
* But variable
- accurate prediction is challenging despite staging and prognostic tools

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ALS management

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Multidisciplinary Care
* Symptomatic and supportive care
* Respiratory
* Bulbar function
* Nutritional status
Disease modifying therapy
* Riluzole – longest standing treatment
* Inhibitor of glutaminergic excitotoxicity
* Increases survival vs. placebo by around 6-18 months

ALS ddx

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Cervical Myelopathy
Kennedy Disease

cervical myelopathy

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Can cause hyperreflexia and spasticity below the lesion
But AT the lesion – causes a lower motor neuron pathology
Can be due to cord compression
Or MRI negative
B12, Vitamin E, Copper deficiency
HIV, HTLV, syphilis, lyme
Autoimune

kennedy disease

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=spinobulbar muscular atrophy
X-linked CAG trinucleotide repeat expansion in androgen receptor
gene
Boys and men from second to 6th decade of life
Motor neuronopathy
Sensory neuronopathy
Endocrine dysfunction – androgen insensitivity
Gynecomastia
Testicular atrophy, reduced fertility
Progression more gradual than ALS

neuromuscular junction (NMJ) diseases

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Proximal more than distal muscle weakness
Fatigable muscle weakness
muscle weakness worsens with use and improves with rest
e.g. worse at end of day, resolves in am, worse at end of meal, etc.
No sensory dysfunction
Myasthenia gravis is the most common disease involving the muscle-nerve
junction

Myasthenia Gravis

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The most common disorder of the NMJ
Autoantiboties against various components of the post-synaptic
muscle membrane
Characteristic fatigable weakness of ocular, bulbar, respirator, axial
and limb muscles
Worsening dysfunction with exercise, use or toward the end of the
day

Myasthenia Gravis - Epidemiology

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Rare disease, but incidence and prevalence have increased over time:
Due to increased recognition, better testing and better treatments
Incidence 5-30 / 1 million person-years
Prevalence 10-20 / 100,000 people

Myasthenia Gravis – Clinical Features

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2/3 of patients have weakness in ocular muscles as first symptom
* Diplopia or blurry vision during periods of extended visual effort
* Driving, reading, working on a computer, watching TV
* Eyelid droop or closure with eye use or when tired

Bulbar muscle weakness:
* Jaw muscle fatigue when chewing
* Coughing or aspirating when eating
* Fatigable slurred speech
* Lack of facial expression

Limb muscle weakness
* Trouble lifting arms over head to wash hair or face
* Trouble climbing stairs
* Trouble getting out of a low chair

Myasthenia Gravis – Investigations

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Antibody Testing
Acetylcholine Receptor Antibody – 75-90%
MUSK antibody – present in 1/3 of AChR
negative patients
Electrodiagnostic testing
Repetitive nerve stimulation – decremental
response due to fatigue
Association with Thymoma
All patients need CT chest once MG diagnosis
is confirmed

Myasthenia Gravis – Treatment

Nonimmunosuppressive Agents * Pyridostigmine * Acetylcholinesterase inhibitor – increases ACh at the NMJ * Main side effects are diarrhea, drooling Immunotherapy * Prednisone * Steroid sparing (a few selected examples) * Azathioprine * Myocphenolate Mofetil * Cyclosporine * Rituximab * Myasthenic crisis: IVIG or Plasma Exchange

Myasthenia Gravis flare

* Infection – eg pneumonia * Iatrogenic * (you don’t need to know specific drugs, but be aware that some drugs can worsen MG) ex. BB, botulinum, aminoglycosides, fluroquinolones, macrolides, Mg IV,

Lambert Eaton Myasthenic Syndrome

* Antibodies against Voltage Gated Calcium Channels (VKCC) * Usually paraneoplastic associated with small cell lung cancer * Weakness IMPROVES with exercise! * more action potentials can open more channels

botulism

* Toxin produced by Clostridium botulinum cleaves SNARE proteins, inhibits release of acetylcholine into the NMJ

myopathies

muscle disease weakness - most often proximal and bilaterally symmetric § occasional conditions cause distal and/or asymmetric weakness ¡ Normal sensation ¡ Usually normal reflexes (reduced if chronic and severe) ¡ May see muscle atrophy (esp. chronic conditions) ¡ Normal or reduced muscle tone ¡ Pain (rarely and usually with destructive processes) ¡ Stiffness, cramping, contracture, myotonia (in specific conditions)

Muscle disease: useful clinical point

Muscle diseases usually present with proximal weakness and normal sensation. Nerve diseases are more likely to present with distal weakness and sensory loss.

Common Causes of Muscle Disease

¡ Acquired: § Inflammatory Myopathies – Dermatomyositis, Polymyositis § Toxic Myopathies – eg. Statin use § Endocrine Myopathies – eg hypo or hyperthyroidism ¡ Inherited: § Muscular dystrophies § Metabolic Myopathies (rare) § Channelopathies (rare)

Muscular dystrophies

* Inherited disorders causing progressive weakness & muscle atrophy * Genetic defect may produce abnormalities in other body systems along with muscle * Recognized according to clinical patterns, pattern of inheritance, and genetic testing. most common: - Duchenne’s and Becker’s muscular dystrophy - Myotonic muscular dystrophy

Duchenne muscular dystrophy

* Annual Incidence 2.1 per 10,000 * Prevalence 1.3-1.8 per 10,000 * Weak shoulder & pelvic girdle muscles * Pseudohypertrophy of calf muscles (due to muscle destruction and CT and fat deposition?) * Wheelchair bound by 10 years, death by 35 years. * X-linked recessive * Kyphoscoliosis & chest wall muscle weakness leads to resp. failure * Genetic defect: Dystrophin gene mutations * Often associated mild cognitive impairment, cardiomyopathy & conduction abnormalities * onset first decade

DMD - gower's sign

proximal muscle weakness requires use of arms to stand up from the ground - can't stand up wtih shoulder and hip extensors

myotonic muscular dystrophy

* Autosomal dominant * Defect : CTG repeat expansion in the DMPK (Dystrophic Myotonia Protein Kinase) gene * Variable clinical manifestations – severity correlates with number of CTG repeats * Muscle symptoms/signs: * Distal arm > leg weakness * Facial and neck weakness * Ptosis * Myotonia * Systemic (non-muscle) symptoms/signs: * Cognitive impairment, Cataracts, Insulin resistance/ diabetes, Cardiac conduction defects, GI dysfunction (e.g. constipation), Impaired sleep * Anticipation occurs - Myotonia in myotonic dystrophy: difficulty in releasing hand grip quickly

NMD continued Flashcards

(35 cards)