Localisation In Clinical Neurology Flashcards
What are the 4 different types of localisation? Give a brief definition and example?
Focal
-single, discrete neuroanatomical locus is responsible for patients symptoms
Eg stroke
Multi focal
-involves more than one locus but loci are discrete
Eg MS
Diffuse
-widespread dysfunction of part of nervous system (effects region of brain in diffuse pattern)
Eg Encephalopathy
Specific pattern
Eg Parkinson disease
What are the main functions of the frontal lobe?
Precentral gyrus= motor cortex for opposite side of body
Inferior frontal gyrus = Broca’a area (DOMINANT HEM)
-speech production (motor component of speech)
Emotions
What are the main functions of the parietal lobe?
Postcentral gyrus= Sensory cortex for opposite side of the body
What are the main functions of temporal lobe?
Memory
Superior temporal gyrus= Wenricke’s area (dominant hemisphere)
-controls speech comprehension
What are the main functions of the occipital lobe?
Controls vision
I.e. can have cortical blindness
Which hemisphere is dominant in most people?
LEFT (±90%)
I.e. tends to correlate with opposite side to dominant hand
What are the 3 segments of the spinal cord? How many vertebrae are in each part of the spinal colume? At what level does the spinal cord terminate?
Cervical= C1-7 Thoracic= T1-12 Lumbar= L1-5
Spinal cord terminates are L1-> becomes CAUDA EQUINA after
What are the 2 nerve roots associated with spinal nerves? What is their function?
Anterior/ventral
- motor neurones exit (ventral= “vehicle” which has motor in the front i.e. anterior)
- cell body in the ventral horn (grey matter)
Posterior/dorsal
- sensory neurone enters the spinal cord
- associated with dorsal root ganglia= cell body of sensory neurone
What are the components of the CNS and PNS?
CNS:
- brain
- spinal cord
- meninges
PNS
- nerve roots incl cauda equina
- plexus (brachial and lumbrosacral)
- nerves
- NMJ
- muscles
How would you differentiate between a lesion in CNS and PNS?
NOTE: 1st step of trying to localise the lesion
CNS= UMN lesion:
- Increased tone i.e. spasticity
- weakness with no wasting
- look for wasting in 1st interosseous space on UL
- brisk reflexes and clonus
- up going plantar
PNS= LMN lesion:
- reduced tone (flaccid)
- weakness + wasting
- fasciculation
- reduced/absent reflexes
- Downgoing plantars (normal)
What is the main motor spinal tract? What are the major landmarks along its course?
Corticospinal
- starts in precentral gyrus = motor cortex
- internal capsule
- decussates in MEDULLA
- terminates by synapsing with anterior horn cell (LMN)
What are the 2 main sensory spinal tracts? How do they differ?
Spinothalamic
- modality= pain and temp i.e. COARSE TOUCH
- decussates at spinal level via white commissure which neurone associate with nociceptor enters
Dorsal column
- modality= position (proprioception) and vibration
- decussates in medulla via medial lemniscus
Why might temperature sensation be lost preferentially to pain? What condition can cause this? (Think about the arrangement of spinal tracts)
Temperature
- Spinothalamic carries pain and temperature fibres BUT temperature fibres are located nearer to the central canal when decussates in central commissure
- leads to temperature fibres >risk of compression
Eg Syringomyelia= fluid-filled cyst in SC
Which receptors are associate with each of the sensory spinal tracts?
Spinothalamic= nociceptors
Dorsal column= proprioceptors + mechanoreceptors
What does an absent reflex indicate?
Lesion at level associated with reflex
What nerve roots are associated with the following reflexes?
Biceps Supinator Triceps Knee Ankle
Biceps= C5/6 Supinator= C6 Triceps= C7 Knee= L3/4 (kick the door) Ankle= S1/2 (in the shoe
You have localised the lesion to the CNS (i.e. UMN lesion). How would you further localise the lesion?
Cerebral= Unilateral presentation-> only one side effected
I.e. stroke
Basal ganglia= Extrapyramidal
-Parkinsonisms= Bradykinesia/resting tremor/rigidity
Cerebellum
- ataxia
- nystagmus
- loss of coordination
Spinal cord
-weakness or parathesia below lesion
You have localised the lesion to the PNS (LMN lesion). How would you localise the lesion further?
Roots= all nerves from root effected
-radiculopathy= dermatomes/muscles/sensation
-unilateral
Eg Sciatica
Plexus
-associated with all nerves of plexus
Nerves
- look at reflexes
- atrophy in associated muscle group
NMJ
- fatigability i.e. MG
- affects proximal muscles
Muscles
What are the 4 different time-intensity profiles a disease might have? Give possible examples.
Acute= minutes to hours
Eg stroke
Subacute= days to weeks
Eg encephalitis/meningitis/subdural haemorrhage
Recurrent-remittent= episodic attacks with degree of recovery of healthy
Eg MS
Chronic-progressive = months to years
Eg Neurodegenerative
How might a patient suffering with a paroxysmal disorder present? Which conditions are classified this way?
NORMAL in presentation-> episode likely to have passed and patient recovered by time presenting for examination or investigation
Headache and facial pain
Seizure and syncope
Transient ischaemic attack
Vestibular disorders
What are the 4 different types of symptoms associated with neurological conditions?
Negative symptoms
- reduction or complete loss of function
- due to partial or complete failure of impulse
Positive symptoms
-exaggeration of physiological phenomenon
Eg seizures/tremor/trigeminal neuralgia
Secondary symptoms
-mass effect symptoms i.e. symptoms to associate with primary lesion
Eg tumour can induce oedema leading to mass effect= raised ICP
Behavioural symptoms
-complexes changes to behaviour or personality
What are the pros and cons of CT/CTA/CTV?
Pros:
- easily available
- easy to use in emergency
- good at detecting intracranial bleeds
- can demonstrate intracranial abnormalities
- can visual arterial aneurysm or venous thrombosis (CTA/CTV)
- can reduce the need for invasive angiography
Cons:
- radiation
- not helpful for demyelinations plaques or spinal cord pathology
What are the pros and cons of MRI/MRA/MRI?
Pros:
- no radiation
- can detect various brain and spinal pathology
- can demonstrate abnormalities in intracranial blood vessels
Cons:
- claustrophobic
- cannot be used for patients with metallic foreign bodies
What is an EEG used for?
Classification of epilepsy NOT diagnosis
Can be routine to look for abnormalities in brain electrical activity
