wk 4 neurology Flashcards
general - schizophrenia and psychotic disorders
- ‘thought disorder’
- disorder of prefrontal cortex
- excess of dopamine in prefrontal cortex
- treat with dopamine antagonist
depressive disorder
- mood disorder
- disorder of limbic function
- deficiency in monoamine in prefrontal cortex
–> serotonin, dopamine, non-epinephrine
treat with lifestyle changes, drugs, therapy, ECT
anxiety disorder
- mood disorder
- disorder of limbic function
- -> amygdala signals increases
- treat with drugs and psychotherapy
personality disorders - 3 clusters
cluster A - odd/ eccentric - eg paranoid, schizoid cluster B - dramatic/ emotional/ erratic - eg antisocial, borderline... cluster C - anxious/ fearful - avoidant, dependant
the 2 pathologies of stroke
'blocked pipe' - ischemic stroke - 80% - area of tissue with inadequate O2 and glucose supply to brain tissue 'burst pipe' - haemorrhage stroke - 20% - local mass due to blood leak into parenchyma leading to area deprives of blood flow and nutrient
WHO defintion
Rapidly developing clinical signs of focal (or global) disturbance of cerebral function, lasting more than 24 hours or leading to death, with no apparent cause other than that of vascular origin
defintion - CNS infarction
brain, spinal cord, or retinal cell death attributable to ischaemia based on pathological, imaging or clinical evidences
defintion - Ischaemic stroke
episode of neurological dysfunction caused by focal cerebral, spinal, or retinal infarction
defintion - silent CNS infarction
imaging or neuropathological evidence of CNS infarction, without a history of acute neurological dysfunction attributable to the lesion
defintion - intracerebral haemorrhage
a focal collection of blood within in the brain parenchyma or ventricular system that is not caused by trauma
stroke caused by intracerebral haemorrhage
rapidly developing clinical signs of neurological dysfunction attributable to a focal collection of blood within the brain parenchyma or ventricular system not caused by trauma
subarachnoid haemorrhage
bleeding into subarachnoid space (between arachnoid and pia mater of brain and spinal cord)
can lead to a stroke
- neurological dysfunction/ headache not caused by trauma
stroke caused by cerebral venous thrombosis
infarction or haemorrhage in the brain, spinal cord, or retina, bc of thrombosis of cerebral venous structure. symptoms or signs caused by reversible edema without infarction or haemorrhage DON’T qualify as stroke
what suplies the brains anterior circulation
internal carotid artery
what supplies the brains posterior circulation
vertebral artery
what does the anterior cerebral artery supply
the strip down the middle of the brain
a couple centimetres from the longitudinal fissure
mostly frontal and parietal lobe
the lower body extremities in the primary motor cortex
what does the middle cerebral artery supply
most of the temporal lobe
on either side of the brain
the upper body in the primary motor cortex
what does the anterior choroidal artery supply
deeper brain matter
what does the posterior cerebral artery supply
mainly the occipital lobe
the bottom of the temporal lobe a bit
the cerebellum
total anterior circulation stroke (TACS)
- large cortical stroke
- in anterior or middle cerebral artery
- 15%
- > unilateral weakness
- > homonymous hemianopia
- > sensory deficit of face/arms/legs, higher cerebral dysfunction
partial anterior circulation stroke (PACS)
- cortical stroke
- in anterior or middle cerebral arteries
- 35%
- > 2/3 TACS
lacunar stroke (LACS)
- subcortical stroke
- in small deep perforating arteries
- 25%
- > pure motor, sensory, sensorimotor (min 2; face, arm, leg)
- > ataxic hemiparesis
posterior circulation stroke (POCS)
- cortical, cerebellum, brainstem stroke
- in posterior cerebral artery, vertebral artery, basilar artery and branches
- 25%
- > cerebellar or brainstem syndrome
- > loss of consciousness
- > isolated homonymous hemianopia
what is apraxia
- inability to perform purposeful movement despite motivation & preserved overall neurological function
- typically localised in left hemisphere
what are executive apraxias
- deficit in ‘sequencing’ complex movements SMA (supplementary motor area ) and PMA (primary m a)
what is posterior apraxia
- deficit in the spatial construction of complex movements
- PPC (posterior parietal cortex)
- eg coming up with idea of how to start movement and orientating how movement would proceed
clinical relevance of cortico-spinal tracts
weakness and spasticity
clinical relevance of basal ganglia loops
movement disorders
clinical relevance of cerebellar loop
coordination disorders
‘hypokinetic’ movement disorders
don't move enough - akinesia - lack of movement - hypokinesia - reduced amplitude of movement - bradykinesia - slow movement - rigidity - change in muscle tone eg parkinsons
‘hyperkinatic’ movement disorder
move too much
- eg chorea
what are the 3 variations of increased tone
spasticity
rigidity
paratonia
spasticity
- ‘clasp knife’ like pen knife
- feel stiff at begin and end of range of movement (when moving a muscle across a joint)
- CST pathology (cotico-spinal tract)
- ‘pyramidal tract disorder’ - UMN
- deep tendon reflexes are primer to contract in their base state
- descending inhibition from cortex all the time
- problems with UMN = inc. in these reflexes
therefore inc. in tone when stretch is max (at begin and end of movement)
rigidity
‘lead pipe’ bc feels like trying to bend a lead pipe
- basal ganglia pathology
- extrapyramidal disorder sign
rigidity throughout the movement of muscle around joint
paratonia
- voluntary resistance
- executive system pathology - cognition
- typically delirium/ dementia
UMN clinical motor patterns
spasticity, brisk reflexes, pyramidal pattern of weakness
- big muscles relatively well preserves compared to smaller ones
- eg biceps stronger than triceps
extrapyramidal clinical motor patterns
rigidity, tremor, normal reflexes, no weakness
hypokinetic movement disorder
eg Parkinsons
- lack of dopamine supply to the basal ganglia
- accumulation of protein alpha-synucleinopathy
- bradykinesia
- rigidity
- tremor
- postural instability
- more in males
Dopamine pathways in the basal ganglia
direct pathway - the accelerator > pro-movement - D2 receptors indirect pathway - the brake; anti-movement - D1 receptors in-balance in these pathways in parkinsons (D1 pathways inc. D2 pathways dec.)
hyperkinetic movement disorders
- jerky movements
eg tremor, chorea, tics - non-jerky movements
dystonia, myoclonus
different types of tremore
at rest
- often extrapyramidal
with actions
- eg extended upper limb or tremor of hands
- enhanced by drugs eg caffeine
essential tremor (10x as common as parkinson’s)
- simple (occurs throughout movement)
- worse towards end of movement (sign of cerebellar disorder)
- task specific disorder (sign of dystonia)
clinical features of cerebellar disorder (VANISHED)
vertigo ataxia nystagmus intention tremor slurred/ staccato speech hypotonia - unusual sign dysdiadochokinesia - problems in alternating movements
how to tell is slurred speech is due to intoxication or not
- global dysfunction of cerebellum = intoxication
- areas of scarring in cerebellum = more staccato pattern (hard to monitor vol. and timing)
vestibulocochlear nerve (VIII)
special sensory
- sensory info relating to hearing and balance
- 1st order neurones in the vestibular and cochlear ganglia pass to vestibular and cochlear nuclei in medulla
glossopharyngeal nerve (IX)
motor
- fibres arise in nucleus ambiguous
- innervates a single pharyngeal muscle which arises from the 3rd and 4th branchial arches
parasympathetic motor
- fibres arise from the inf. salivatory nucleus and pass to the optic ganglion
- post-ganglionic fibres innervate the parotid gland
sensory
- provide sensory info from pharynx - post. 1/3rd of tongue and middle ear
- 1st order neurones lie in the ganglion and pass to the trigeminal sensory nucleus
- important in gag reflex
special sensory
- taste info passes from posterior 1/3rd of the tongue and the pharynx to the nucleus solitarius
- info from the carotid body and carotid sinus passes to the nucleus solitarius
Vagus nerve (X)
main parasympathetic motor nerve of the body
- Fibres arise from the dorsal motor nucleus and pass to a number of ganglia within the cardiovascular, respiratory and gastrointestinal systems
Motor
- Fibres arise from the nucleus ambiguous and innervate muscles of soft palate, pharynx, larynx, oesophagus which arises from the 3rd and 4th branchial arches
- important in swallowing and speech
Sensory
- Provides sensory info from the pharynx, larynx, tympanic membrane and part of outer ear
- 1st order neurones lie in the ganglion and pass to the trigeminal sensory nucleus
- important in gag reflex
Special Sensory
- taste info passes from the pharynx to the nucleus solitarius
- info from the aortic body ad aortic arch pass to the nucleus solitarius
accessory nerve (XI)
motor
- LMN/s in nucleus ambiguous and in anterior horn of the upper cervical cord
- Innervate trapezius and sternomastoid
- test by asking patient to shrug shoulders
what nerves are involved in swallowing
9 (glossopharyngeal) and 10 (vagus)
- activates sympathetic fibres through vagus nerve
what nerves are involved in sneezing
9, 10, 11, 5
- complex
- spinal reflexes from lower part of spinal cord also activated
jugular foramen
- lower cranial nerves (IX, X. XI) may all be affected at base of the skull (jugular foramen) by tumour, trauma or inflammation
- XII leaves skull vis hypoglossal foramen and is only affected by large tumours
hypoglossal nerve (XII)
Motor
- innervates extrinsic and intrinsic muscles of the tongue
- LMNs are in the hypoglossal nucleus
- unilateral lesions result in weakness and atrophy of the tongue on the the affected side
- when protruded the tongue deviates towards the affected side
bulbar and pseudobulbar palsy general
bulbar refers to the motor nuclei of the brainstem
- strictly the medulla “bulb”
- corticobulbar fibres pass from the cortex to brainstem nuclei
- as with elsewhere in motor system there are UMN (pseudobulbar) and LMN (bulbar) lesions
bulbar palsy LMN clinical symptoms
atrophy, fasciculation of innervated muscles
- Dysphonia, dysarthria and dysphagia are seen in both
- seen in MND(chronic) and Guillain-Barre(acute)
pseudobulbar UMN
usually have to be bilateral lesions due to bilateral innervation – exaggerated nerve reflexes (jaw) and spastic paresis of the tongue
- Dysphonia, dysarthria and dysphagia are seen in both
- seen in vascular disease and demyelination
segments of the spinal cord
o 8 cervical o 12 thoracic o 5 lumbar o 5 sacral o 1 coccygeal o 31 in total
how far does the spinal cord descend
Spinal cord descends to L1/2 in adult
But L3/4 in children
what are the nerve roots below the spinal cord called
CORDAEQUINA
craniocervical region
- Articulation between cervical level 1 and the skull
- Thick envelope formed by the dura and arachnoid
- Rootlets of the spinal nerves – here these are relatively short in length
- Dorsal root ganglia in close relation to the intervertebral foramina
- Dura of spinal cord continuous with dura of the cranial cavity
parts of the lumbosacral cord
-The conus medullaris
o The lower limit of nervous tissue
-Filum terminale
o A cord of connective tissue linking the conus medullaris and the 1st coccygeal vertebrae
-Corda Equina
o Long rootlets of spinal nerves at end of spinal cord
Lower end of the lumbar cistern at S2 where the dura matter narrows to envelop the lower part of the filum terminale
what are the different sensory pathways
- Dorsal columns – fasciculus cutaneous and fasciculus gracillis
- Spinothalamic tracts
- Direct spinocerebellar pathways
- Dorsal and ventral spinocerebellar pathways
different motor fibres in the spinal
- Ventral and lateral corticospinal tracts
how does the spinal cord sit in relation to vertebral body
- Sits in central part of vertebral body
- Posterior – spinous and transverse processes
- Anterior vertebral body
- Dorsal root ganglia – 1st order neurones of sensory fibres
- Arachnoid and dura envelope spinal nerve roots as they come out form the spinal cord
route of sympathetic fibres in the peripheral nerve
- Symp. Fibres run out through ventral nerve root and exit peripheral nerve via white rammus communicans
- Enter sympathetic ganglion of appropriate level
- Symp. Ganglia make sympathetic chain – fibres run up and down this
- Exit via grey ramus communicans
- Re-enter spinal nerve and run off to supply viscera
upper spinal cord lesion clinical features
- Spastic tetraplegia, hyperreflexia, extensoplanta responses
- Incontinence and sensory loss below level of region
- Proprioceptive problems
lower cervical lesion clinical features
- Affect upper limbs if upper
- Affect lower limbs if lower
- Sensation affected up to the level of the lesion
hemisection of the cord (Brown-Sequard)
- Ipsilateral loss of proprioception
- UMN signs
- Contralateral loss of pain and temp. sensation
clinical examination for diagnosing UMN and LMN lesions
o Test reflexes for hyper-hypo reflexia o Test for flaccid or spastic paralysis o Eg tap on patella tendon – Cause stretch in tendon itself Changes to intrafusal muscle fibres Result in sensory input back through spinal cord causing alpha-motor neurone activation and muscle contraction at same time in activation of the opposing muscle group
blood supply of the spinal cord
o single anterior spinal arteries
o And paired posterior spinal arteries
o Many anterior spinal artery supplies come directly from the aorta
anterior spinal artery thrombosis
- Commonest of spinal vascular disorders
- Ant. Spinal artery – 2/3rds of spinal cord
- Post. 1/3rd
- Occlusion to ant. Spinal artery=
o Initially LMN signs
o Progress to UMN signs
o Loss pf pain and temp. sensation
o Loss of autonomic functions
o Preservation of proprioception through posterior columns
peripheral nerve lesions clinical symptoms
- Particularly in accident and emergency]
- Brachial plaxus
o Traction lesions
Upper roots (C5 + C6) Erb’s palsy, “waiter’s tip” position of the arm
Lower roots (C8 + T1), “claw hand” deformity - Neoplastic movement
- Post-irradiation
radial nerve (C6-C8)
-Damaged by fractures to the mid-shaft of humerus
-Compression at same site leading to “Saturday night paralysis’
o Loss of extension of wrist and fingers (wrist drop)
median nerve (C5-T1, predominantly C6)
- Carpal tunnel syndrome – predominantly sensory but maybe associated with wasting of thenar muscles
Ulnar Nerve (C7, C8, T1)
- May be damaged by injury at the medial epicondyle of the elbow, or at medial aspect of wrist
- Damage to ulnar nerve = “claw hand” deformity
Femoral Nerve
- May be damaged by post. Hip dislocation, pelvic fracture, tumours in the pelvis
- Leads to weakness of knee extension
o Results in inability to lock knee while walking - Wasting of quadriceps
Sciatic Nerve (L4-S3)
- Composed of 2 large trunks which are bound together and separate in mid-thigh
o Tibial nerve
o Peroneal nerve - Damage to the sciatic nerve can be due to trauma, neoplastic compression/ infiltration, or operative complication
- Results in foot drop and unstable ankle
compression or irritation of a spin al nerve root which comprises the sciatic nerve
- Symptoms dependant on the nerve root
- COMMON
o L5 – sensory – pain in posterolateral thigh and leg, numb inner foot
Motor – weakness of dorsiflexing foot and toes
o S1 – sensory – pain in posterolateral thigh and leg, numb lateral foot
Motor weakness of foot dorsiflexion and loss of ankle jerk - RARE
o L3+L4 – diminished knee jerk, pain in anterior thigh
prolapsed intervertebral disc
- many causes of sciatica
- eg osteocytes in lower part of spine
- prolapse of intervertebral disc
- structure of intervertebral disc
o annulus fibrosis around outside
o fluid nucleus polyposis - annulus fibrosis can deteriorate (particular Post.)
- prolapse of nucleus polyposis material which puts pressure of nerve root behind thus
lumbar more common
common peroneal nerve (L4-S2)
- This can be damaged as it winds round the head of the fibula
- Eg fracture or compression (eg tight casr)
- Result in weakness of foot dorsiflexion and eversion
