Approach To Assessment Of Neurological Disorders Flashcards
What is the role of the frontal lobe?
Intellectual function, high level thinking, bladder continence and motor function.
What is the presentation of frontal lobe dementia?
Bladder dysfunction
Change in appetite
Disinhibited behaviour
What is the corona radiata?
White matter sheet formed of projection fibres which allows information to communicate between the brain cortices. It continues as the internal capsule.
What is the internal capsule?
White matter structure located between the Globus Pallidus and the caudate nucleus and thalamus of the basal ganglia. It consists of fibres for connections to the cortex and receives fibres from the corpus striatum.
How do fibres travel in the motor system?
Motor cortex to -> Corona radiata to -> internal capsule -> cerebral peduncles in midbrain.
Where do cranial nerve 1 and 2 arise?
Cerebrum.
Where do cranial nerve 3 and 4 arise?
Midbrain
Which cranial nerves arise from the medulla?
Cranial nerve 9, 10, 11, 12
Which cranial nerves arise from the pons?
Cranial nerve 5, 6 and 7.
Where do motor fibres decussate?
Majority decussate at the medullary pyramids of the medulla to form the lateral corticospinal tract.
-> The rest continue ipsilaterally as the anterior corticospinal tract.
What is an upper motor neuron?
Originates in the cortex and travels to the brain stem or spinal cord.
What is a lower motor neuron?
Originates in the spinal cord and projects to the muscles and fibres.
What is the presentation of UMN damage?
Hypertonia, hyper-reflexia and spasticity with positive Babinski sign.
What is the Babinski sign?
Stimulation of the lateral plantar aspect of the foot causes Dorsiflexion of the foot, instead of extension. This indicates upper motoo
What is the role of the temporal lobe?
Memory
Olfactory sense
Hearing and balance
Emotion
What is the role of the occipital lobe?
vision
What is the role of the parietal lobe?
Contains the somatosensory cortex for sensory integration, receptive and language.
What is the difference between the parietal lobe in the dominant hemisphere?
Parietal lobe in the dominant hemisphere is responsible for language. Lesion here results in dyslexia, acalulalia, finger agnostic and poor left-right discrimination.
What is the effect of a lesion in the parietal lobe of the non-dominant hemisphere?
Visuospatial apraxia- inability to perform a task when asked
Sensory extinction
What is acalulalia?
Loss of ability to perform simple calculations, which occurs in parietal lobe lesion of the dominant hemisphere.
What causes a contra lateral sensory deficit?
Lesion in the thalamus, internal capsule or parietal cortex.
What is Weber syndrome?
Ischaemic stroke of midbrain posterior cerebral artery affecting Cranial Nerve 3 of oculomotor. Results in ptosis, diplopia(double vision) and contra lateral motor dysfunction.
What is Wallenberg syndrome?
Ischaemic stroke of the posterior inferior cerebellar artery, resulting in lateral medulla infarction where the inferior cerebellar peduncles are located, resulting in cerebellar dysfunction,
-> Impaired gag reflex, Horner’s syndrome, ataxia and sensory loss.
What is the role of the brain stem?
Respiratory centre
Cardiac centre
Reticular activating system for wakefulness
Where is the vestibulocerebellum located?
In the vermis to maintain posture and balance,
Where is the spinocerebellum located?
Located in the paravermis to coordinate muscle movement and maintain postural tone.
Where is the pontocerebellum located?
Cerebellar hemispheres for planning movements and fine movement.
Which side do cerebellar lesions present?
Ipsilaterally.
How do cerebellar lesions present?
Ipsilateral Vertigo, ataxia, intention tremor, hypotonia.
ROLE OF THE MEDIAL GENICULATE?
Located in the thalamus for vision.
Role of the lateral geniculate?
Located in the thalamus for auditory processing.
What is the role of the anterior and centromedian region of thalamus?
Mood and emotion.
What is the role of the vector posterior region of the thalamus?
Sensation.
What is the components of the neurological exam?
Cognitive function
Cranial nerves
Sensory nerves
Motor system
Gait
Romberg’s test
How is Cranial nerve 1 tested?
Place a finger over one nostril and ask the patient to sniff with the other.
What causes damage to Cranial Nerve I?
Mucous membrane inflammation due to infection
Stretching and tearing of the nerves when hitting the front or back of the head.
How is Cranial Nerve II tested?
Eye examination which includes visual acuity by looking at an eye chart
Pupillary light reflex
Visual fields
Fundal examination with a fundoscope.
What is papilloedema?
Swelling of the optic nerve due to raised intracranial pressure which may result in vision disturbances sometimes, a marker for brain pathologies.
What is optic neuritis?
Inflammation of the optic nerve due to an infection associated with PAIN and vision loss.
How does a CN III lesion present?
Oculomotor nerve mainly innervates the extraocular muscles. Eye is abducted and positioned slightly down. It cannot adduct and there is partial ptosis due to paresis of the levator palpabrae superioris, which is innervated by parasympathetic supply of oculomotor
When doing the pupillary light reflex, the pupil remains dilated.
Why is there not complete ptosis in CN III lesion?
Muller’s muscle/superior tarsal muscle is responsible for keeping the eyelid open, and receives sympathetic nerve supply.
What is the presentation of CN IV lesion?
Superior oblique is non-functional because of a trochlear nerve lesion so there is difficulty looking DOWN and IN.
How does Horner’s syndrome present?
Lesion above T1 in the sympathetic chain which results in partial ptosis, anhydrosis and miosis (constricted pupil) which may dilate in darkness.
How does a Cranial Nerve VI lesion present?
Inability to abduct the eye to the affected side, due to non-functional lateral rectus muscle.
What is diplopia?
Double vision.
What is Bell’s palsy?
Lesion of the facial nerve after it arises from the pons which causes ipsilateral muscles of facial expression paresis, causing inability to raise eyebrows, scrunch eyes and smile.
Where do upper motor neurons of the facial nerve arise?
Arise from the Cerebral cortex and they synapse with the facial nerve nuclei in the pons. Supplies the contralateral bottom half of the face.
Where do lower motor neurons of the facial nerve arise?
Arises from the facial nerve nuclei in the pons to innervate the muscles of facial expression in the upper and lower face. Lesion affects the ipsilateral upper and lower half of the face with incomplete eye closure and impaired taste sensation
How are the muscles of the upper face innervated?
UMN from the contra lateral cerebral cortex and ipsilateral cerebral cortex.
LMN fibres will be ipsilateral.
How are the muscles of the lower face innervated?
UMN fibres only from the contra lateral cerebral cortex.
LMN fibres will be ipsilateral.
How does a CN VIII nerve lesion present?
Hearing and balance are impaired, and when conducting Rinne’s test, bone conduction is better than air conduction. Patient may have vertigo.
How does a CN IX nerve lesion present?
Glossopharyngeal lesion causes impaired swallowing and taste and sensation to the posterior 1/3 of the tongue
How does a CN X nerve lesion present?
Vagus nerve lesion presents as loss of gag reflex due to inability to move the palate or the pharynx, faster heart rate, and urination of the bladder via parasympathetic nerve supply.
How does a CN XI lesion present?
Accessory nerve lesion causes absent function of sternocleidomastoid and accessory nerve.
What provides the sensory component for the gag reflex?
Glossopharyngeal nerve.
What provides the motor component for the gag reflex?
Vagus nerve.
How does a CN XII lesion present?
Weakness or wasting of the tongue which deviates to the side of the weakness, fasiculations and dysarthria (unclear speech).
What is tested in a motor examination?
Muscle tone
Power
Tendon reflexes
What is decorticate posturing?
In response to noxious stimuli, there is abnormal flexion of the upper arms and extension of the legs, caused by damaged to the corticospinal tract.
What is the decerebrate posturing?
In response to noxious stimuli, there is extension of the arms and pronation of the wrists.
How is muscle power graded?
Scale of 0-5 with:
0: no movement
1: flicker of movement
2: movement with no power
3: power against gravity
4: power against resistance
5: normal power
How is the plantar response assessed?
Scratching the lateral sole of the foot should cause plantarflexion. If there is dorsiflexion, it is a positive Babinski sign which indicates UMN lesion
What is motor neurone disease?
Degeneration of motor neurons which presents depending on the site of the lesion.
How can the spinothalamic tract be tested?
Pinprick and temperature test.
How can the dorsal column be tested?
Joint sense and propioception test.
How is the corticospinal tract arranged in the spinal cord?
Most lateral is the lower limbs, medial is the head and upper limb.
How is the spinothalamic tract arranged?
Lower limbs are most lateral, upper limbs and head are most medial.
How is the dorsal column pathway arranged in the spinal cord?
Most lateral is the head and upper limb, most medial is the lower limbs.
What happens in cervical disc prolapse?
Causes ipsilateral LMN lesion, which may affect the brachial plexus and causes biceps muscle wasting.
What happens in vertebral disc prolapse?
Causes ipsilateral symptoms with loss of knee reflex, L4/L5 dermatomes are affected so loss of innervation to muscles and pain with leg raise.
What is Brown-Sequard syndrome?
Contralateral spinothalamic symptoms and ipsilateral dorsal column.
What is central cord lesion?
Injury to the central part of the cervical spinal cord which causes loss of control to the fingers and upper limb, with the lower limb being less affected.
What is anterior spinal artery syndrome?
Ischaemia of the anterior spinal artery. Dorsal column function is maintained but complete loss of spinothalamic tract and motor function.
What is Romberg’s test?
Test for balance and propioception to get patient to stand with feet together and walk with eyes closed.
