Neuro - Altered Conscious Level and Neurological Disturbance Flashcards
Loss of consciousness spectrum and summary of causes
Spectrum:
Syncope/Blackout
Impaired conscious level
Coma
Causes: BBBMF Brain Beat (Heart) Blood Metabolic "Failure" (organ)
Loss of Consciousness - Brain
Presentation and DDx
Neurological - Impaired conscious level/coma
Diffuse intracranial:
SAH, Epilepsy, Meningitis, Encephalitis
Hemisphere lesion [Cerebral]:
Subdural, Extradural, Stroke/TIA
Brain stem [Brainstem/Cerebellar]:
Any of the above - Raised ICP pushes on brain stem
Peripheral Nervous system:
Peripheral (Autonomic) Neuropathy
Hyponatraemia
Hypocalcaemia
“SHIT”
abscesS
Haemorrhage
Ischaemia/Infarct
Tumour (primary/secondary)
Loss of Consciousness - Beat
Presentation and BP formula
Cardiac –> Blackouts
Syncope - Loss in consciousness due to a sudden drop in blood pressure
BP=HRxSVxTPR
Components of BP formula
HR: Bradycardia + Arrhythmias
SV (inc. Outflow obstruction):
Tamponade, Cardiomyopathy
Left: HOCM/Aortic stenosis
Right: PE
TPR (inc. Neuropathy):
Vagal overactivity
Peripheral (autonomic) neuropathy
Loss of Consciousness - Blood
Presentation
Blood/Vasculature –> Impaired consciousness/Blackout
Venous - Pooling
Arterial - Atherosclerosis e.g. Vertebrobasilar insufficiency (TIA, CVA), shock
Anaemia
Metabolic causes of impaired conscious level/coma
Hypoglycaemia/Hyperglycaemia Hyper/Hypocalcaemia Hyper/Hyponatraemia Drug overdose/poisoning/toxins Addisonian Crisis, Myxoedema
Organ failure causes of impaired conscious level/coma
Hepatic encephalopathy
Uraemic Encephalopathy
Hypoxia/CO2/Narcosis (COPD)
–>Liver/Kidneys/Lungs
Blackout - COLLAPSED
Carotid Sinus Syncope Orthostatic (Postural) Hypotension refLex - Vasovagal (Neurocardiogenic) Syncope Low Glucose (Diabetics) Arrhythmia/Stroke's Adam's Attack Panic (--> Anxiety --> Hyperventilation) Situational Syncope Epilepsy Drop Attacks
Brain Haemorrhages
Extradural: Classic ‘lucid interval’ before LOC = arterial bleed
Subdural: Hx of falls, progressive confusion = venous bleed between dura and arachnoid layers
Subarachnoid: sudden severe headache = bleeding into the subarachnoid space. Half of all patients lose consciousness and altered mental status is common.
Brain - Raised ICP
Raised ICP –> Space occupying lesion –> Abscess/Haemorrhage/Infarction/Tumours (SHIT); Oedema; Head injury
Raised ICP compressive signs
Headache Nausea and Vomiting Altered GCS Papiloedema Focal neurology Pupil changes - dilatation; down and out.
Raised ICP herniation
CN III (opthalmoplegia)
Ataxia
Apnoea
Transient Loss of Consciousness
Either increased vagal or decreased sympathetic activity
Carotid Sinus Syncope
Hypersensitive Baroreceptors –> Excessive reflex bradycardia +/- vasodilation on minimal stimulation, e.g. head turning/shaving
refLex - vasovagal (neurocardiogenic syncope)
Reflex Bradycardia +/- vasodilation provoked by emotion/pain/fear/standing too long
Transient Arrhythmias (Stroke’s Adam’s attack)
–> Decrease in Cardiac Output –> LOC.
Collapses with no warning, pale, slow/absent pulse; Recovery in seconds, patient flushes, pulse recovers
Situational Syncope
Cough, Effort (e.g. exercise; cardiac origin), Micturition (mostly men)
Postural Hypotension
Definition, Presentation, Diagnosis
Drop in systolic BP > 20 mmHg or diastolic BP > 10 mmHg after standing for 3 mins vs lying
Elderly
Hypovolaemia
Drugs (Nitrates, Diuretics, Antihypertensives, Antipsychotics)
Peripheral Neuropathy –> Inadequate Vasomotor reflex (insufficient sympathetic increase in HR/vasoconstrution) = DM, Parkinson’s disease, MSA, Autonomic Neuropathy
Endocrine = Addison’s, Hypopituitarism (decreased ACTH)
Good history and Lying/Standing BP should be enough to diagnose. Confirm with Tilt test
Aortic Stenosis
Definition, Presentation, Clinical signs
Narrowed valve orifice
20% due to congenital bicuspid valve
Most common cause in adults is calcification of normal trileaflet valves
Presents with…
Dyspnoea
Chest Pain
Syncope
Clinical signs…
Harsh ejection systolic murmur heard loudest at the right upper sternal edge at end expiration, which radiates up towards the carotids.
Narrow pulse pressure
Slow rising pulse
Hypoglycaemia presentation
Symptoms present when glucose <3mmol/L:
Mainly Diabetic on NEW insulin/Oral hypoglycaemic + exercise
Alcohol, Liver Failure = risk factor –> Decreased hepatic glucose production.
Symptoms; Sweating Weakness Decreased GCS: Drowsiness --> LOC Palpitations and anxiety
Blackout Investigations
Depends on suspected cause
Bedside: Examination - Cardio, Neuro, Lying/Standing BP Fluids: FBC, UandE, Glucose, ABG Imaging: ECG/Cardiac Monitor/24 hr tape Echocardiogram EEG, CT/MRI
GCS Summary
Glasgow Coma Scal eis the most commonly used scoring system for initial assessment and monitoring of a patient’s level of consciousness.
Assessment of…
Eye opening (4)
Best Verbal Response (5)
Best Motor response (6)
AVPU
Primary survey
Alert
responds to Vocal stimuli
responds to Pain
Unresponsive
GCS Detailed
Motor 1-6: No response to pain Extensor response to pain Flexor response to pain Withdrawing to pain Localising to pain Obeying commands
Verbal 1-5: None Incomprehensive sounds Inappropriate speech Confused (disoriented) Oriented (time/place/person)
Eyes 1-4: None In response to pain In response to voice Spontaneous
GCS score ranges and implications
3: Globally no response
8 or less: Coma, Severe injury, Consider airway
9-12: Moderate injury
13-15: Minor injury
Stroke Definition
Rapidly developing clinical signs of focal or global disturbance of cerebral function, with symptoms lasting 24 hrs or more, with no apparent cause other than that of a vascular origin.
TIA Definition
Transient ischaemic attacks are acute episodes of focal loss of cerebral function lasting less than 24 hrs, which are attributed to an inadequate blood supply.
UMN lesion clinical features
Contralateral Signs – motor and sensory NO fasciculations NO muscle wasting Spasticity Weakness – Extensors-Arms; Flexors-Legs Hyperreflexia Upgoing Plantar response Pronator Drift
Anterior Cerebral Artery
anatomy and pathophysiology
Frontal and parietal lobes
Disturbance of judgement
Loss of social behaviour
Contralateral hemiparesis leg > arm
Mild sensory deficit
Middle Cerebral Artery
anatomy and pathophysiology
Frontal, Parietal, Temporal Lobe, Subcortical Structures (e.g. Basal Ganglia) Internal Capsule
Contralateral hemiplegia arm/face/thorax > leg
Aphasia (Broca & Wernicke’s areas)
Hemisensory deficits
Posterior Cerebral Artery
anatomy and pathophysiology
Occipital and Lower Temporal Lobe
Visual Defects:
Homonymou hemianopia
Visual agnosia
Prosopagnosia
TIA Clinical Features
(Common in SBAs is a description of) Focal neurological deficit unilaterally, e.g. Amaurosis Fugax
(Transient and painless loss of vision in one eye due to the passage of an embolus into the central retinal artery).
TIA Ix/Rx
CT Head to exclude a haemorrhagic aetiology immediately.
- -> Depressed consciousness (GCS < 13)
- -> Suspected haemorrhage (drugs etc) or Raised ICP
Consider thrombolysis with tPA if within the 4.5 hour window and there are no contraindications.
–> Thrombolysis is done with Alteplase (tPA) at 10% bolus, 90% infusion at a dose of 0.9mg/kg
Presentation after the 4.5 hr window is managed with aspirin.
All people presenting with acute ischaemic stroke should be given aspirin.
Seizures/Epilepsy
Definition and Pathophysiology
Seizure - A paradoxical discharge of cerebral neurons –> External manifestations
Epilepsy - A recurring tendency to have seizures.
Before: epileptic aura (marks onset), triggers (flashing lights)
During: stiffness, jerking, incontinence, side tongue-biting, sweating, palpitations, mouth frothing, pallor, cyanosis
After: muscle ache, post-ictal confusion/drowsiness
Seizures may be partial (focal) or generalised (involving both hemispheres)
Partial seizures
Categorization and complications
Simple Partial
[Focal motor/sensory/autonomic/psychic]
Awareness unimpaired
No post-ictal confusion
Complex Partial
[Deja-vu, depersonalisation, altered emotion, epigastric fullness; can start as simple partial (=aura)]
Most commonly arise form the temporal lobe
Awareness/consciousness is impaired
Post-ictal confusion common
Partial seizures Localising Features
Frontal lobe
Behaviour Motor – posturing, peddling Dysphasia/speech arrest Motor arrest, subtle behaviour disturbances Jacksonian March
Partial seizures Localising Features
Temporal Lobe
Complex Emotional disturbance Hallucinates (smell/taste) Depersonalisation Automatisms
Partial seizures Localising Features
Parietal Lobe
Sensory disturbance – tingling, numbness
Motor symptoms – abnormal movement/rhythmic muscle contractions
Partial seizures Localising Features
Occipital Lobe
Visual phenomena - spots, lines, flashes
Primary Generalised Seizures
Pathophysiology
Convulsive vs Non-Convulsive
Convulsive:
Tonic - limb stiffening
Clonic - limb jerking
Tonic-Clonic - LOC followed by a stiff body with flexed elbows and extended legs followed by violent shaking with eyes rolling (grand mal), incontinence, post-ictal and drowsiness
Myoclonic - sudden isolated jerk of limb, face or trunk; disobedient limb –> thrown to the ground
Non-Convulsive:
Absence - 10s or fewer of vacancy, sometimes myoclonic jerks (petit mal), presents in childhood - no post ictal.
Atonic (Akinetic) - Sudden loss of muscle tone, ‘Drop Attacks’. No LOC
Status Epilepticus
Definition and Rx
Continuous seizure or serial (at least 2) discrete seizures between which there is incomplete recovery of consciousness of at least 30 min duration.
–> Medical Emergency
Rx:
ABC - open and maintain airway, recovery position
Oxygen 100%
Stop seizures –> Slow IV Bolus Lorazepam (1) 204mg
–> Lorazepam (2) if no response in 10 mins
Continuing seizures –> IV Phenytoin/Diazepam
Encephalitis
Definition, Causes, Signs, Ix
Brain parenchyma inflammation - may be focal symptoms
Causes
Viral - HSV, CMV, EBV, VZV
Non-viral - Any bacterial meningitis, TB, cryptocossus, etc
Bizarre Encephalopathic behaviour
Decreased GCS/Coma
Focal signs
Seizures
CT - cerebral oedema - compressive symptoms (Medical Emergency
Meningitis
Meningeal Inflammation
Causes:
Meningococcus
Pneumococcus
Headache Meningism Decreased GCS/Coma Focal signs Seizures Fever Rash Kernig's sign + Brudzinski +
Encephalitis vs Meningitis
Encephalitis:
Compressive symptoms/focal YES
Seizures YES
Altered Mental State YES
Meningitis:
Meningism YES
Seizures < encephalitis
Altered mental state < encephalitis
Metabolic LOC/Seizures
Presentations and Causes
Hyponatraemia (<135)
Headaches, comiting, drowsiness, seizures
Thiazide Diuretics (Hypo/Eu/Hypervolaemic)
Hypocalcaemia
e.g. complicatoin of thyroid surgery (loss of parathyroids)
4 CATS - Consulvsions, Arrhythmia, Tetany, Spasms
Chvostek’s and Trousseau’s signs (Face and hand)
