Neurology Flashcards
Differentials for bilateral ptosis
congenital
bilateral horner’s (syringomyelia)
myotonic dystrophy
myasthaenia gravis
differentials for bilateral LMN facial weakness
bilateral bells pallsy, sarcoidosis, GBS, Facioscapulohumeral (FSH) dystrophy, myotonic dystrophy
how to investigate myasthenia gravis
bloods including looking for antibodies to acetylcholine receptors, striated muscle, muscle sensitive tyrosine kinase
electrophysiology- repetitive stimulation and single fibre electromyography
pathophysiology of myasthenia gravis
a disorder characterised by antibodies targetting the nicotinic acetylcholine receptors on the post synaptic membrane of the neuromuscular junction.
antibodies in MG
85-90% of patients have anti nicotinic acetylcholine receptor antibodies, other antibodies are muscle specific tyrosine kinase receptors and striated muscle antibodies
which drugs can exacerbate myasthenia gravis
aminoglycosides, pencillamine, fluroquinolones, macrolides, beta blockers, phenytoin
what conditions are associated with MG
diabetes, hypo/hyperthyroidism, pernicious anaemia, RA, pemphigus
What other conditions present in a similar fashion to MG/ what are differentials
botulism, miller fisher syndrome, LEMS, mitochondrial myopathy
what is the difference between MG and LEMS
LEMS caused by antibodies directed at pre synaptic voltage gated calcium channels.
Contrary to MG, there is no fatiguability with repetitive movement.
what are the treatment options for MG
1st line are long-acting acetylcholinesterase inhibitors such as pyridostigmine
The majority of patients eventually require additional immunosuppression:
prednisolone initially
azathioprine, cyclosporine, mycophenolate mofetil may also be used
thymectomy
Management of myasthenic crisis
plasmapheresis
intravenous immunoglobulins
what are the side effects from acetylcholinesterase inhibitors
e.g. pyridostigmine
side effects are incresed muscarinic activity which can result in excessive lacrimation, salivation, N+V, diarrhoea
what is the role of thymectomy in patients with myasthenia gravis
T lymphocyte tolerance to autoantigens develops in the thymus. Patient with thymomas have more severe weakness and higher antibody titres. Thymectomy can result in medication free remission. It may also be considered in the absence of thymoma to improve symptoms and induce remission.
what are some of the causes of peripheral sensorineuropathy
sensory polyneuropathy:
metabolic- diabetes, hypothyroid,
nutritional deficiencies: vitamin B12 deficiency, thiamine B1 deficiency, B6
toxins- alcohol, vincristine, isoniazid
immune- RA/SLE
vasculitis- GPA
neurological cause- CIDP
infections- HIV
nerve conduction studies- demyelinating (more immune mediated and require specialist input) / axonal
how to investigate causes of peripheral neuropathy
Bloods: FBC
ESR- inflammatory disorders
CTD screen
renal profile, LFT
immunoglobulins, electrophoresis
nerve conduction studies- most are axonal vs demyelinating (CIDP/ GBS)
causes of a peripheral motor neuropathy
motor polyneuropathy
GBS
lead toxicity
porphyria
HSMN
chronic inflammatory demyelinating polyneuropathy
if you suspect GBS what investigations would you do
management
I would take an ABCDE approach
FVC to assess respiratory involvement- <1.5L would warrant ITU involvement
ECG for arrythmia risk
history of diarrhoea- stool sample to look for campylobacter
IVIG, plasma exhange
What are the features of autonomic neuropathy
postural hypotension
urinary retention
impotence
ileus
what are other causes of pes cavus
unilateral: malunion of fractures, burns, polio spinal trauma, spinal cord tumour, congenital/idiopathic
bilateral: freiderichs/ muscular dystrophies, spinal muscular atrophy, cerebral palsy, hereditary spastic paraperesis, spinal cord tumours
what is the inheritence of HSMN
autosomal dominant inheritence pattern
mutation of PMP22 gene on chromosome 17
why are pain and temperature inaffected in patients with HSMN
pain and temperature sensation is carried in the unmyelinated fibres therefore these sensations are unaffected
management of multiple sclerosis
MDT approach
physiotherapy for mobility
OT for walking aids
in acute deterioration- high dose corticosteroids, and counsel about long term steroid use
long term medical management- disease modifying treatments such as IFN B and glatiramer
monoclonal abs such as alemtuzumab and natalizumab can also be used
what are the cranial nerve signs associated with MS
Intranuclear opthalmaplegia - failure of one eye to adduct and nystagmus of other eye on abduction suggests lesion of medial longitudinal fasiculus
RAPD
optic atrophy
reduced visual acuity
what are the diagnostic criteria of MS
CNS demyelinating plaques causing neurological impairements seperated by time and place
What clinical features may be present with MS
autonomic dysfunction- urinary incontinence, impotence, bowel problems
Uthoff’s phenomenon- worsening of symptoms after a hot bath or exercise
lhermittes syndrome- lightening pains down the spine on flexion of neck due to cervical cord plaques
how does multiple sclerosis affect pregnancy
reduced relapse rate during pregnancy but an increased risk of relapse in the post partum period
generally safe for foetus although there is a possible reduction in birth weightc
causes of a spastic paraperesis
myelopathy
compressive- degeneration e.g. disc herniation/ vertebral disc disease.
tumour- primary or metastatic
trauma
infection- epidural abscess, spinal TB, viral (polio, CMV, EBV)
Potts, vertebral osteomyelitis
haematoma
congenital
vascular- spinal infarcts, arteriovenous malformation
inflammatory- MS (transverse myelitis), sarcoid, CTD SLE
metabolic- B12 deficiency
degenerative- MND, HSMN, hereditary spastic paraparesis