Neurology Module 1 Flashcards
What are the four parameters of localisation?
- Mentation - when abnormal likely forebrain or brainstem dysfunction
- Behaviour - Always a sign of FB problems as this part of the brain modulates personality
- Posture - abnormal postures at rest, head tilt/head turn
- Gait - May be affected secondary to lesions in several areas
What are 5 types of mentation
- Alert - normal, responsive to environment
- Disoriented - Abnormal response to environment
- Depressed/obtunded - inattentive and less responsive to environment
- Stuporous - unconscious but responsive to noxious stimuli
- Comatose - unconscious and unresponsive to anything including painful stimuli
What would be the mentation of a FB lesion v. Brainstem lesion?
FB Lesion - disoriented/depressed
Brainstem Lesion - more extremem stuporous/comatose
What common behaviour changes are seen with forebrain lesions?
Aggression, compulsive walking/circling, loss of leant behaviour and excessive vocalisation (cats)
what are 3 types of gait
Ataxia: vestibular, cerebellar, spinal
Paresis: weakness, reduced voluntary movement divided into ambulatory v. non-ambulatory
Plegia: complete voluntary loss
What are the postural reaction tests and why are they done?
- They test the awareness of precise positions and movement of the body
- proprioceptors are located in muscles, tendons, and joints and they transmit signal to the cerebral cortex where they are consciously preceived, also present in inner ear to collect info regarding head movement
1. Proprioception positioning
2. Hopping
3. Placing reactions - small breed dogs/cats
What are the three main functional units of the brain?
Forebrain
Brainstem
Cerebellum
What is the vestibular system divided into?
Central - w/n brainstem and cerebellum
Peripheral - inner ear + vestibulocochlear nerve (8)
What are clinical signs of forebrain lesions?
- Mentation: Altered mentation - disoriented/depressed
- Contralateral blindness (normal PLR) and facial hypoaesthesia
- Posture: Circling, head turn/pressing
- Gait: Normal gait
- Pacing
- Gait: Decreased postural response in contralateral limbs
- Seizures/hemi-neglect
- Behaviour changes
What are clinical signs of a brainstem lesion?
- Mentation: Depressed, stuporous, coma
- Severe CN deficits
- Paresis of all or ipsilatearl limbs
- Decerebrate rigidity
- Neck pain (sometimes)
- Decreased posture response on all or ipsilateral limbs
- Resp or cardiac abnormalities (RAAS center)
What are clinical signs of cerebellum lesions?
- Mentation: normal
- Vestibular signs
- Decerebellate rigidity
- intentional tremor of eye + head
- hypermetria, broad based stance, hypermetria
- delayed postural reflexes
- generalised ataxia
What are signs of central vestibular disease?
Paresis: possible
CNS deficits: 5-7CN may be affected
Proprioceptive: possible
Mentation: may be affected
Horners: Rare
Nystagmus: vertical/horizontal/rotary
What are signs of peripheral vestibular disease?
Paresis: No
CNS deficits: 7 may be affected
Proprioceptive deficits: no
Mentation: no
Horners: possible
Nystagmus: horizontal, rotary
Why does vestibular disease cause a headtilt?
Normally the head tilt is ipsilateral
Vestibular system gives tone to neck muscles and when diseased it loses tone on the side of the head and it tilts
Which way and why does the head tilt with cerebellar disease
Cerebellum antagonises the vestibular system so when not working to antagonise there is extra tone and the head tilts the opposite way of the lesion
What are things that can look like a seizure?
Syncope
Sleep disorders
Vestibular disease
Dyskinaesia
Head tremor
Neuro-muscular disease
Signs of seizures?
- At rest or sleep usually
- Usually short <5mins
- Typically pre and post ictal signs
- Impaired consciousness during event
- Presence of autonomic signs - salivation, urination, defecation
- convulsions/oro-facial muscle movements
What are movement disorders?
Group of diseases characterised by involuntary movement
EEGs.- normal and conscious with no autonomic signs
What are the investigations for seizures?
Rule out reactive seizures with - haem, comp, lytes, urinalysis, fasted BA, ammonia, glucose
MRI + CSF
How are seizures classified?
Idiopathic
Reactive - response from a normal brain to a
transient disturbance
Structural
What are the 4 stages of status epilepticus and how are they treated?
Stage 1: early status <30mins - BZPs (hyper tension/glycaemia/thermia/CBF)
Stage 2: established status 30-120mins - Phenobarb, levitiracetam (hypo tension/glycaemia/CBF
Stage 3: refractory >120mins - ketamine, propofol infusions, midaz CRI (inhibitory receptors stop working and only excitatory work NMDA, AMPA)
Stage 4: Super-refractory - after 24hrs
What is intracranial pressure and what makes it up?
ICP is the pressure within the skull related to volume of the contents
The contents: Brain, blood supply and CSF
If one component increases then the other has to decrease - brain not very compliant
What are clinical signs of intra-cranial pressure?
Mentation changes: stuporous, comatose - compromise in ARAS (ascending reticular activating system)
Cushings reflex: bradycardia with hypertension - late marker already ischaemic
Changes in pupil size - will progress as ICP gets worse, starts with one and spreads
Posture: Abnormal posture decerebrate v. decerebellate
Ultimately leads to brain herniation
Where can the brain herniate?
Cerebellum via rostral foramen magnum
Rostral brain stem - will cause dilated pupils
What causes the Cushing’s reflex?
Caused by alpha-1 receptor activation –> increased sympathetic activation –> hypertension through vasoconstriction and the carotid baroreceptors detect the hypertension and try to decrease through bradycardia by increasing vagal tone
When analysing CSF what do you look at and where can you get a sample and what are contraindications for CSF sampling?
Where to get
Cervical: cerebromedullary cistern
Lumbar: Subarachnoid space
What to look at:
- total nucleated cell count
- Protein
- Differential cell count
- Neutrophilic - SRMA, MUO, Bacteria
- Mononuclear - MUP, chronic SRMA
- Mixed: MUO, bacterial, SRMA
- Eosinophilic
Contraindicated with
- Increased ICP
- Fractures
- Clotting problems
- Chiari-like malformations
