Neuro Flashcards
SAH risk factors
female age >50 smoking OCI alcohol HTN Connective tissues disorders PKD FHx previous SAH coarctation of aorta fibromuscular dysplasia
WFNS
I – GCS 15, no motor deficit II – GCS 13-14, no motor deficit III – GCS 13-14, motor deficit IV – GCS 7-12 +/- motor deficit V – GCS 3-6, motor deficit present or absent
modified fisher scale
grade 0
no subarachnoid haemorrhage (SAH)
no intraventricular haemorrhage (IVH)
incidence of symptomatic vasospasm: 0% 3
grade 1
focal or diffuse, thin SAH
no IVH
incidence of symptomatic vasospasm: 24%
grade 2
thin focal or diffuse SAH
IVH present
incidence of symptomatic vasospasm: 33%
grade 3
thick focal or diffuse SAH
no IVH
incidence of symptomatic vasospasm: 33%
grade 4
thick focal or diffuse SAH
IVH present
incidence of symptomatic vasospasm: 40%
Note: thin SAH is < 1 mm thick and thick SAH is >1 mm in depth.
Poor prognositc signs with SAH
pre-existing severe medical illness clinically symptomatic vasospams delayed cerebral infacrt hyperglycaemia fever anaemia medical complications including pneumonia and sepsis
Causes of neurological deterioration following SAH
metabolic causes - CO2, O2, ammonia, temp, pH ,electrolytes, glucose
Drugs
Seizures
intracranial hypertension
hydrocephalus
re-bleed
Complications following SAH
re-bleed - highest risk in first 6 hours
acute hydrocephalus - see drop in GCS, sluggish papillary response, bilateral downward deviation of eyes
Vasoospasm
Delayed cerebral ischamia
Parenchymal haematoma
Seizures
HypoNa
Medical complications - arrythmias, liver dysfunction, neurogenic pulmonary oedema, pneumonia, ARDS, renal dysfunctio
vasospasm definition
dynamic narrowing of vessels
delayed neurological deterioration
clinically detected neuro deterioration after stabilisation that is not due to rebleeding
may be due to multiple other causes
delayed cerebral ischamia
any neurological deterioration (focal deficit, GCS drop by 2 or more) for >1 hour
presumed due to ischaemia - all other causes exlcuded
risks for vasospasm
higher radiological grade - esp if blood in basal cisterns or lateral ventricles
age <50
hypertension
hyperglycaemia
no difference if aneurysm coiled or clipped
prevention of vasospasm
oral nimodipine - 60mg q4H for 21 days
reduces risk of ischamic stroke by 34%
risks for seizures post SAH
MCA clots infarction clipping poor grade
VTE prophylaxis after SAH
all should have UFH unless unsecured and awaiting intervention
Should be started at least 24 hours after aneurysm secured
Modified Rankin score
used to show neuro/disability outcomes - used by ISAT trials
0 - 6
0 - no symptoms
3 - moderate disability - requires help, but can walk without assisstance
4 - moderate severe - unable to walk or attend own needs without assistance
6 - dead
Causes of aseptic meningitis
viral - most common (often enterovirus or coxsackie) partially treated bacterial meningitis TB meningitis fungal lymphoma sarcoidosis
causes of seizures with meningitis
raised ICP
cerebritis
cerebral abcess
septic venous thrombus
Main point on cryptococcal meningitis
- who it affects, how Dx, treatment
can cause a chronic meningitis
seen in immunocompromised
CSF should be stained with india ink
Treat with amphoteracin B
May need to aggressively Mx raised ICP (eg daily CSF drainage)
Encephalitis - definition and causes
viral infection of the brain
may be due to direct infection or by post-infectious immune medicated mechanisms
HSV 1 most common - affects frontal and temporal lobes; 25% mortality, even with treatment
Arboviruses - japenese enceph, west nile virus
Antibody medicated - NMDA receptor encephalitits
Clinical presentation of encephalitits
key - focal neurological signs indicating involvement of parenchyma
- esp speech disturbance, seizures, altered cognition, LOC
Clinical signs of cerebral venous thrombosis
headache
focal deficits - esp cranial nerves
seizures
papilloedema
third nerve palsy
down and out ptosis mydriasis Failure of light reflex (but consensual constriction of the opposite eye is intact) Failure of accommodation
Can be injured due to trauma or ischaemia/infection
- the parasympathetic fibres often spared with non trauma so pupillary response is preserved
fourth nerve palsy
paralysis of superior oblique
vertrical diplopia
patient can’t look down and in
onlu cranial nerve to innervate opposite side - so lesion in contrlateral to eye affects
very small nerve - at risk of damage during trauma
sixth nerve palsy
paralysis of lateral rectus
unable to turn eye out - results in horizontal gaze palsy
diplopia
risks of cerebral venous/sagital sinus thrombus
infection - meningitis, epidural/subdural abcess, facial/dental infection
DKA
COCP
ecstasy use
GBS investigations
CSF - high protein, some have high WCC, may have oligoclonal banding
Bloods - high IgG, antiganglioside GM1 antibodies
Nerve conduction studies
- reduced conduction velocity
- multifocal conduction blocks
MRI - to exlcude high cervical lesion
Lung function
- if FVC <20 - transfer to ICU
- if <15 - intubation
Screen for infection -
- viral PCR/antibodies
- stool for campylobacter
- mycoplasma antibodies
Clinical findings GBS
minor illness 2-8 weeks before
25% have motor weakness, 50% paraesthesia, 25% both
Flacid paralysis in ascending pattern areflexia cranial nerve in 45% autonomic dysfunction sensory loss is mild pain may be a major feature
Miller fisher varient GBS
cranial nerves predominate
ataxia, areflexia and opthalmoplegia
stongly associated with campylobacter jejuni
may have GQ1b antibodies
Treatment of GBS
Plasmapheresis - most effective if carried out within 7 days of symptoms
IVIG - 2g/kg over 2-5 days
10% will replase with either- most will respond well to a second course
no point in doing both
no poing in crossing over
Indications for intubation in GBS
VC <15ml/kg
VC rapidly falls over 6 hours
respiratory failure
if secretions are difficult to manage
- NB - may have severe bulbar involvement ( LMN CN 9, 10, 12)
Drugs that may cause CVS instability in GBS
Low BP - morphine, frusemide, thio
Increased BP - ephedrine, dopamine, isoprenaline,
arrhythmias - sux
Poor prognostic features of GBS
> 60yrs
rapid progression or quadrapersis in <7 days
need for ventilation
preceding diarrhoeal illness
Critical illness polyneuropathy
acute
diffuse
a motor neuropathy, due to axonal degeneration
presents in recover phase of illness
quadriparetic weakness
hyporeflexia
difficulty weaning
high mortality (likely related to underlying condition)
Critical illness myopathy
linked with asthma and some drugs (steroids, NMBDs, aminoglycosides)
reflexes and sensation usually normal
CK often raised
muscle necrosis is seen on histology
Intensive care acquired weakness (ICUAW)
occurs in upto 45% patients who need ventilation, have sepsis, have MOF
Usually associated with long period of immobilisation
CLinical signs
- normal cognitiion
- sparing of cranial nerves
- symmetrical flaccid paralysis
subgroups -
- polyneuropathy
- myopathy
Treatment of MG
anticholinesterase drugs - pyridostigmine
steroids
IVIg - 5 days may have long term benefit
thymectomy
Triggers of MG crisis
infection pregnancy surgery drugs - - Abx - Antiarrythmics - LAs - muslce relaxants - analgesia
Factors predicting need for ventilation post op in MG patient
long pre-op duration of MG
high anticholinesterase requirement
co-existant resp disease
pre-op viral capacity of <2.9L
Key points about motor neuron disease
no treatment, progressive group of related disorders
Affects both upper and lower motor neurons
Pathogeneisis -
- cerbral cortex, anterior horns of spinal cord - shrinkage and degeneration
- lateral sclerosis
Present -
- asymmetrical insidious weakness and wasting
- more symetrical with progression
- have spactisity, hyperreflexia and muscle wasting
Dx made on clinical grouds and EMG showing denervation
Mx - riluzole (glutamate antagonist) may slow progression slightly
SHort notes on botulism
caused by endotoxins from clostridium botulinium
Irreversibly binds to cholinergic nerves at NMJ, postganglionic parasympathetic nerve endings and autonomic ganglia
may be food bourne or from food
Symptoms -
- GI upset
- dry eyes and mouth
- general weakness - symmetrical, descending
- early CN involvement
treatment is supportive
can use metronidazole for wound botulism
most patients improve in a week or so
tetanus clinical presentation
due to spores from clostridium tetani
muscle rigidity and spasms
autonomic instability - severe increase in sympathetic drive most significant (although parasympathetic surge may be [re-terminal)
management of tetanus
neutralise circulating toxin
- human anti-tetanus immune globulin - IM
source control and limitation of toxin production
- debridement and cleaning of wound; metronidazole
control of spasms
- avoid stimulation
- sedation, paralysis
Management of autonomic dysfunction
- magnesium
- labetelol
- clonidine
- sedatives
initiation of full active tetanus immunisation (different site from HIG)
Delirium definition
a disturbance of consciousness that develops over a short period of time, fluctuates and is associated with perceptual changes, such as hallucinations
Clinical subtypes of delirium
Hypoactive - most common
Hyperactive - only 5% of cases
Mixed
impact and relevance of delirium in ICU patients
seen in upto 70% ventilated patients
patients have a 3x higher 6/12 mortality
associated with long term cognitive decline and early dementia
Pathophysiology of delirium
neuroinflammation impaired oxidative metabolism altered cerebral blood flow increased BBB permeability neurotransmitter imbalance -> cholinergic hypoactivity relative state of dopamine excess
Modifiable risk factors for delirium
infection use of opiates and sedative drugs immobility polypharmacy low Na, O2, pH and raise CO2 use of physical restraints used of IDC pain sensory impairment sleep disturbance anticholinergic drugs
non-modifiable risk factors for delirium
>65 dementia depression cognitive impairment liver impairment institutionalised resident
Screening tools for delirium
Confusion assessment model for ICU (CAM-ICU)
- assesses for fluctuating mental status, inattention, altered LOC and disorganised thinking
- is a point in time assessment
Intensive care delirium screening checklist (ICDSC)
- assessed over a nursing shift
RASS score
Richmond agitation and sedation scale
+4 - combative
0 - alert and calm
-3 - movement or eye-opening to voice (no eye contact)
-5 - no response to voice or physical stimulation
dexmedetomidine MOA
alpha 2 agonist
- sedative action mediated by post synaptic receptor agonism in locus ceruleus
- analgesic action medicated by posy synaptic receptor agonism in the brain and spinal cord
dexmedatomidine side effects
transient HTN hypotension, brdycardia, nausea
dexmedatomidine dose
0.1 - 1mcg/kg/min infusion
can load with 1mcg/kg over 10mins
dexmedatomidine evidence
Lancet 2016 -
- pts >65 in ICU after non-cardiac surgery
- n =700
- showed a marked decrease in delerium incidence (23 –> 9%)
- also less tachycardia and HTN
DahLIA trial 2016
- included patients in whom extubation was delayed due to severe agitation
- found more ventilator free hours with use of dexmed
BUT - underpowered
pharmacological treatment for delerium
haloperidol - if QTc ok
- 2.5mg doses, max 18mg in 24 hours
- SEs - extrapyramidal effects, neuroleptic malignant syndrome, torsades, not for use in parkinsons
Olanzapine - 5mg, max4 doses
- use if CI to halp
risperidone
dexmedatomidine or clonidine
benzos
- only to be used if safety is an issues
- have been linked to 7x increase in delirium in burns patients
Preconditions for brain stem testing
cause for coma consistent with brain death
at least 4 hours with - GCS3, pupils non reactive, no cough, apnoea
nomothermia (>35)
normotension (MAP >60, SBP >90)
no sedation or analgesia
absence of severe electrolyte, metabolic and endocrine disturbance
intact neuromuscular function
ability to access one eye and one ear
ability to perform apnoea test (no high spinal injury, severe resp failure)
brain stem testing
- preconditions met
- TOF
- GCS3 - no response to deep nail bed pain in all 4 limbs, no response to CN V and VII
- pupils fixed, non responsive - 2 and 3
- no corneal reflex - 5 and 7
- no oculo-vestibular reflex - 3, 4, 6, 8
- no gag bilaterally - 9 and 10
- no cough - 10
- positive apnoea test
testing oculo-vestibular reflex
inspect external auditory canal to ensure eardrum visible
head to 30
instil 50mls ice cold water into canal
watch eyes with eyelids held open, for 60 seconds
apnoea test
pre-oxygenated for 5 mins
disconnect from ventilator and supply oxygen (2l/min) down catheter into ETT
watch chest
no breath with PaCO2 >60, or increase by 20 from baseline if retainer
- would expect a rise by 3/min
Investigations for brainstem testing
4 vessel intraarterial angiography with digital subtraction
- injected into carotids (no flow above siphon) and vertebrals (no flow above foramen magnum)
Radionucleotide imaging -
- lack of perfusion accross BBB to be retained by brain parenchyma
CT angio - less experience, with no large studies done
- absent enhancement at 60 seconds in different cerebral artery distributions
- MCA, PCA, pericallosal arteries and internal cerebral arteries
MR - not recommended
Doppler -
- used to rule out, not in
Brain death testing with regards to children
if over 30 days - same as adults
Term newborn
- minimum period of observation 48 hours
- two examinations done, >24 hours apart
<36/40
- clinical determination can not be done with certainty
Responsibilities of ICU staff in organ and tissue donation
care of dying patient
care of their family
recognising the possibility of organ donation
determination of death
respectful treatment of the dead patient
discussing the option of organ donation with family
liason with donor coordination service
maintaining physiological stability
aftercare for the family (irrespective of if donation occurred)
Absolute contraindications to organ donation
HIV
CJD
metastatic or non curable malignant disease
history of malignancy that poses high risk of transmission (melanoma)
Relative contraindications to organ donation - need individual consideration
past malignancy with a long cancer free interval
treated bacterial infection
infection with hep B and C
risk factors for HIV and viral hepatitis
Common medical issues seen in potential donors
CVS -autonomic storm followed by loss of sympathetic flow
- issues with arrhythmias common
- fluid management difficult as varies depending on organs being donated
- target MAP >70
DI
- hyperNa associated with worse outcome for liver and kidney recipients
- DDAVP early - 2-4mcg q2-6hrs prn
Hypothermia
- due to;
- reduced whole body heat production
- inabiliy to conserve heat
- loss of hypothalamic thermoregulation
Anterior pituitary function
- replacement is not routinely used
Anaemia and coagulopathy
- products as needed
Respiratory - ongoing routine cares
Nutrition - continue enteral feeds