Neurodegenerative diseases Flashcards
Name the descending tracts and what they do
MOTOR Lateral corticospinal tract - main voluntary motor - upper extremity motor pathway, more medial Ventral corticospinal tract - voluntary motor
Name the ascending tracts and what they do
SENSORY Dorsal columns - deep touch - vibratory - proprioception Lateral spinothalamic tract - pain - temperature Ventral spinothalamic tract - light touch
Risk factors for MS
HLA DLR1*15 allele More common in young white, women - nordic origin Associated with autoimmune conditions - psoriasis
Signs and sx of MS
Impaired coordination (action and intention tremor, ataxic gait)
Optic neuritis
Motor weakness (spasticity, pyramidal signs, spastic gait)
Sensory disturbances
Fatigue
What signs would be seen on fundoscopy for MS?
papillitis, diplopia, nystagmus, internuclear ophthalmoplegia
What is lost in MS?
Loss of myelin and oligodendroglial + axonal pathology (chronic inflammatory, demyelinating disease of CNS)
Types of MS
Relapsing-remitting (80-85%) - doesn't always convert to secondary progressive Primary progressive (15-20%) - progresses into clinical phenotype eventually Secondary progressive (follows RR after 10-15yrs) - clinical phenotype
*you can give steroids to relieve acute inflammation but as the disease progresses, you are left with residual sx
How is a MS diagnosis made?
Key to MS diagnosis:
- dissemination in space
- dissemination in time
- absence of alternative diagnosis
The following us used to aid diagnosis:
- clinical hx + examination
- radiological exam (MRI)
- lab evidence (CSF)
- electrophysiology (VEPs)
What contrast is used in MRIs for MS and why?
Gadolonium contrast used to distinguish between old and new lesions
Older lesions are darker than new
BBB leaks for up to 6 weeks after acute inflammation
What is present in CSF for MS?
Oligoclonal bands present in CSF but not serum (if matched, suggests inflammation is systemic)
- AI condition so B cells release IgG antibodies that target myelin
What causes myasthenia gravis?
‘Grave muscle weakness’, autoimmune condition
- antibody attacks ACh receptor so muscles unable to contract
- the more you use the muscle/need it, the more ACh required thus muscle fatigues
- MUSK (muscle-specific kinase) also leads to impaired transmission
How does myasthenia gravis present?
Muscle fatigue WITH USE
- ptosis, diplopia, dysarthria, dysphagia, +/- SOB
- normal reflexes
- relieved after periods of rest
Occurs in young adult women (<40yo)/older men (>60yo)
What are ix for myasthenia gravis?
Bloods = anti-AChR or anti-MUSK
- can be seronegative
EMG = demonstrates muscle fatigue
CT/MRI = look for thymomas* (pot. malignant)
*MG associated with thymic hyperplasia (70%) and thymoma (10%)
How does Lambert Eaton Myasthenic Syndrome present?
Difficulty swallowing Weakness in upper arms and shoulders Similar sx to MG Autonomic: dry mouth, constipation, incontinence Muscle function better after use Hyporeflexia
What causes LEMS?
Immune system attacks Ca2+ channels required to trigger ACh release
Decreased ACh means unable to form normal muscle contractions
Repeated use leads to cumulative openings of Ca2+ channels so eventually ACh increases
Which conditions are associated with LEMS?
Small cell lung cancer (50-60% cases)
- older onset, >60yo, smoker
Autoimmune conditions
- young age of onset, <35yo
Ix for LEMS
Bloods - anti-VGCC
EMG
CT/MRI - cancer detection
How may motor neurone disease present?
Impaired swallowing + speech Sparing of oculomotor, sensory + autonomic function (bladder, bowel, sexual function) Progressive muscle weakness Dysphagia SOB More common in men
Signs of MND
UMN
- increased tone, hyperreflexia, Babinski’s
LMN
- decreased tone, hyporeflexia, fasiculations, atrophy
- wasting of thenar hand muscles (base of thumb)
- wasting of tongue muscles (bulbar onset)
What protein builds up in MND?
Ubiqunated proteins in cytoplasm of motor neurones build up and kill corticospinal tracts
*90% of pts with ubiquitin inclusions +ve for TDP-43
