Neurolocalisation (Overview + Where in the CNS) Flashcards
State the structures involved in the general motor pathway.
State the result of a break in the motor axis
General motor pathway:
UMN –> LMN –> NMJ –> muscle
Break in the motor axis = weakness
State the 2 components of extrapyramidal components.
State the result of a lesion in one or both of the components.
Extrapyramidal components
1. basal ganglia
2. cerebellum
Result of lesion in extrapyramidal component = not strictly weakness but imprecise movement if cerebellum
State some conditions (6) confined to the CNS
- troke
- epilepsy
- multiple sclerosis
- dementia
- parkinson disease
- encephalitis
State some conditions confined to PNS (5)
- brachial neuritis
- peripheral nueropathies in GBS
- mononeuritis multiplex
- myasthenia gravis
- myositis
State some conditions that can affect both CNS and PNS (4)
- vitamin B12 deficiency
- vasculitidis (including sjogrens)
- syphilis / HIV
- freidreichs ataxia
Recall the structures involved in
(1) Motor axis
(2) Extrapyramidal system
(1) MOTOR AXIS
UMN –> LMN –> NMJ –> muscles
(2) EXTRAPYRAMIDAL SYSTEM
- basal ganglia
- cerebellum
State the components of the motor axis and their locations (CNS/PNS)
UMN - CNS
Basal ganglia - CNS
Cerebellum - CNS
LMN - CNS (only cell body) and PNS (majority)
NMJ - PNS
Muscle - PNS
State the 3 functions of the reflex arc
- prevents overstretching of muscle
- helps maintain posture
- generates tone
Explain the features of UMN and LMN lesion with reference to:
1. inspection
2. tone
3. power
4. reflexes
5. plantars
6. coordination
7. others
UMN LESION
- Inspection = pyramidal posture
- Tone = clasp-knife rigidity
- Power = pyramidal pattern weakness
- Reflexes = brisk
- Plantars = upgoing plantar
- Coordination = compromised
- Others = spastic gait, hoffman reflex, clonus
LMN LESION
- Inspection = wasting and fasciculations
- Tone = flaccid or normal
- Power = weak
- Reflexes = absent
- Plantars = downgoing plantar
- Coordination = compromised
- Others = foot drop
With regard to LMN lesions,
- Reflex arc is ____ ____
- Inspection =
- Tone =
- Power =
- Reflexes =
- Plantars =
- Coordination =
- Others =
Name the example of this LMN lesion.
With regard to LMN lesions,
- Reflex arc is COMPLETELY BROKEN
- Inspection = WASTING + FASCICULATIONS
- Tone = FLACCID OR NORMAL
- Power = WEAK
- Reflexes = ABSENT
- Plantars = DOWNGOING
- Coordination = COMPROMISED
- Others = FOOT DROP
CHARCOT-MARIE TOOTH SYNDROME
With regard to UMN lesions,
- ____ level of ____ of reflex arc is ____
- Inspection =
- Tone =
- Power =
- Reflexes =
- Plantars =
- Coordination =
- Others =
With regard to UMN lesions,
- HIGHER level of MODULATION of reflex arc is LOST
- Inspection = PYRAMIDAL POSTURE
- Tone = CLASP-KNIFE RIGIDITY
- Power = PYRAMIDAL PATTERN WEAKNESS
- Reflexes = BRISK
- Plantars = UPGOING
- Coordination = COMPROMISED
- Others = SPASTIC GAIT, HOFFMAN REFLEX, CLONUS
Cord lesion in anterior half of the spinal cord at level T12 can result in
1. ____ signs at that level.
2. ____ signs below that level
Cord lesion in anterior half of the spinal cord at level T12 can result in
1. LMN signs at that level.
2. UMN signs below that level
State the 3 elements of movement
- power
- coordination
- quantity
State the important cord levels and outlets (4)
C3-5 - phrenic N (keep the diaphragm alive)
C5-T1 - brachial plexus
L1-S4 - lumbosacral plexus
S2-4 - sphincteric supply (keep the shit off the floor)
State the structures in the cerebral hemispheres and structures in the brainstem
CEREBRAL HEMISPHERE
1. grey matter (cortex)
2. white matter
3. basal ganglia
BRAINSTEM
1. midbrain - CN III and CN IV nucleus, gaze centres, reticular formation of reticulospinal tract
2. pons - CN V, CN VI, CN VII, CN VIII nuclei, gaze centre (horizontal PPRF), long tracts
3. medulla - CN IX, X, XII nuclei, cerebellar connections
Brain has a ____ cross section –> lesion in brain is likely to affect ____ side(s) (____)
Spinal cord has a ____ cross section –> lesion in the spinal cord is likely to affect ____ side(s) (____ or ____)
- As cord carries ____ ____, cord lesions result in ____ symptoms
Brain has a LARGE cross section –> lesion in brain is likely to affect ONE side(s) (CONTRALATERAL HEMIPARESIS)
Spinal cord has a SMALL cross section –> lesion in the spinal cord is likely to affect BOTH side(s) (PARAPERESIS or QUADRUPARESIS)
- As cord carries SPHINCTERIC EFFERENTS, cord lesions result in UROLOGICAL symptoms
hemiparesis = weakness in one side
paraperesis = weakness in both legs only
quadruparesis = weakness in all 4 limbs
With reference to spinal cord, state the results of a cervical and thoracic cord lesion
CERVICAL CORD LESION
- quadruparesis = weakness in all 4 limbs
- bilateral incontinence (due to sphincteric supply at level of S2-S4)
THORACIC CORD LESION
- paraperesis = weakness in bilateral legs
- bilateral incontinence (due to sphincteric supply at level of S2-S4)
RECALL:
State the structures involved in the different parts of the brainstem.
State the effects of lesions at each part of brainstem with relation to the structures mentioned.
(1) MIDBRAIN
- CN III + CN IV nuclei - cranial nerve deficit (double vision)
- Vertical gaze centres (riMLF) - gaze palsies (opthalmoplegia + vertigo)
- Reticular formation - loss of consciousness + cheyne stoke breathing (increasing duration of breathing)
(2) PONS
- CN V + CN VI + CN VII + CN VIII nuclei - cranial nerve deficit
- Horizontal gaze centres (PPRF) - gaze palsies (opthalmoplegia + vertigo)
- Long tracts - locked in syndrome (if bilateral damage), UMN signs and weakness (contralateral hemiparesis), sensory symptoms
(3) MEDULLA
- CN IX + CN X + CN XII nuclei - cranial nerve deficit
- Cerebellar connections - ataxia and vertigo
sympathetic outflow = horner syndrome
State the levels in the brainstem where each cranial nerve exits
MIDBRAIN - 3, 4
PONS - 5, 6, 7, 8
MEDULLA - 9, 10, 12
State the presentations associated with lesion in midbrain
LESION IN MIDBRAIN
1. CN III + CN IV nuclei - cranial nerve deficits (diplopia)
2. Vertical gaze centres (riMLF) - gaze palsies (ophthalmoplegia + vertigo)
3. Reticular formation - loss of consciosness + chyne stoke breathing (continuous increasing duration between each breath)
State the presentations associated with lesion in pons
LESION IN PONS
- CN V + CN VI + CN VII + CN VIII nuclei - cranial nerve deficit
- Horizontal gaze centres (PPRF) - gaze palsies (ophthalmoplegia + vertigo)
- Long tracts - weakness and sensory symptoms + locked in syndrome (if bilateral lesions)
State the presentations associated with lesion in medulla oblongata
LESION IN MEDULLA OBLONGATA:
- CN IX + CN X + CN XII - cranial nerve deficits
- Cerebellar connections (spinocerebellar and cerebellocortical tracts) - ataxia and vertigo
State the presentation associated with lesions in the cerebral hemisphere
LESION IN THE CEREBRAL HEMISPHERE
1. UMN lesion and contralateral hemiparesis
2. Cognitive issues
3. Visual field deficits
Recap: UMN lesions
- Inspection = PYRAMIDAL POSTURE
- Tone = CLASP-KNIFE RIGIDITY
- Power = PYRAMIDAL PATTERN WEAKNESS
- Reflexes = BRISK
- Plantars = UPGOING
- Coordination = COMPROMISED
- Others = SPASTIC GAIT, HOFFMAN REFLEX, **CLONUS*
State the difference in presentation of subcortical and cortical lesions.
SUBCORTICAL LESIONS
- in white matter
- UMN lesion + contralateral hemiparesis + sensory deficits
CORTICAL LESIONS
- in grey matter
- UMN lesion + contralateral hemiparesis + sensory deficits + cognitive issues + visual field defects
State the 4 higher cognitive functions the cortex is involved in, state their corresponding dominant/non-dominant hemisphere and presentation of their deficits.
State the presentation associated with lesions in the cerebellum
LESIONS IN THE CEREBELLUM
- no UMN signs
- if lesion is in cerebellar hemisphere –> ipsilateral limb ataxia (upper and lower)
- if lesion is in cerebellar vermis –> truncal ataxia
OTHER SIGNS
- nystagmus
- dysmetric saccades
- broken pursuit
- cerebellar dysathria
- finger nose dysmetria
- dysdiadochokinesis (inability to rapid alternating muscle movements)
- ataxia
- broad base gait
With regard to anterior cord syndrome, state the
1. affected tracts
2. cause
3. presentation
With regard to anterior cord syndrome, state the
1. affected tracts = spinothalamic, lateral tracts (+/-)
2. cause = anterior spinal artery occlusion –> spinal infarct
3. presentation = loss of pain and temperature, LMN signs at level of lesion, UMN signs below level of lesion
With regard to posterior cord syndrome, state the
1. affected tracts
2. cause
3. presentation
With regard to posterior cord syndrome, state the
1. affected tracts = DCML tract, lateral tracts
2. cause = b12 deficiency OR syphilis (tabes dorsalis) OR copper deficiency
3. presentation = loss of proprioception and vibration sensation, LMN at level of lesion, UMN signs below level of lesion
With regard to brown-sequard syndrome, state the
1. affected tracts
2. presentation
With regard to brown-sequard syndrome, state the
1. affected tracts = ipsilateral DCML, contralateral spinothalamic, ipsilateral corticospinal (lateral tracts)
2. presentation = loss of proprioception and vibration, loss of pain and temperature sensations, ipisilateral UMN weakness
