Neurology 1 Flashcards
What does the anterior cerebral artery supply?
Medial surface of the cerebral hemisphere as far back as the peri-occipital sulcus
What does the middle cerebral artery supply?
2/3 of the lateral surface of the brain
What do the central middle cerebral arteries supply?
Corpus striatum, thalamus and internal capsule
What does the posterior cerebral artery supply?
Corpus callosum plus cortex of occipital and temporal lobes
What do the central posterior cerebral artery supply?
optic radiation, sub thalamic nucleus and thalamus
What is the blood supply of the brainstem and cerebellum?
Vertebral and basilar arteries
What is the function of CNI (Olfactory)
Special sensory - smell from the nasal mucosa
What is the function of CNII (Optic)
Special sensory - vision from the retina
What is the function of CNIII (Oculomotor)
Somatic motor: 4/6 extra-ocular muscles, levator palp superioris
visceral motor: pupil constriction
What is the function of CNIV (trochlear)
Somatic motor - superior oblique mm
What is the function of CN V (Trigeminal)
Ophthalmic nerve : VI = sensory to superior third of the face and the cornea
V2: sensory to median third of the face and maxilla
V3: sensory - sensation over the mandible and lower lip
MOTOR: muscles of mastication: masseter, pterygoids
What is the function of CNVI (Abducent)
Somatic motor: Lateral rectus mm
What is the function of CNVII (facial)
Somatic motor: muscles of facial expression
Visceral motor: submandibular/sublingual glands, lacrimal
Special sensory: taste from the anterior 2/3 of the tongue
General sensory: skin of the external acoustic meatus
What is the function of CNVIII? (VC)
Special sensory: hearing (vestibular nerve) and balance (cochlear nerve)
What is the function of CN IX (gloss)
Somatic motor: stylopharyngeus
Visceral motor: parotid gland
Special sensory: posterior 1/3 of the tongue
general sensory: sensation from the external ear and pharynx
Visceral sensory: visceral feedback from the carotid body
What is the function of CN X (vagus)
Somatic motor - palatal / laryngeal / pharyngeal muscles of swallowing
Visceral motor: parasympathetic innervation to smooth muscle of trachea, bronchi, digestive tract and heart
Visceral sensory: same areas as motor
special sensory: taste from the epiglottis / palate
General sensory: sensation from the auricle and external acoustic meatus
What is the function of CNXI (spinal accessory)
Motor: SCM, trapezius
What is the function of CNXII (hypoglossal)?
Motor: intrinsic / extrinsic muscles of the tongue
Where is the nucleus of CNI?
Olfactory epithelium
Where is the nucleus of CNII?
Retinal ganglion cells
Where is the nucleus of CN III and IV?
Midbrain
Where are the nuclei of CN V, VI and VII?
Pons
Where is the nucleus of CN VIII?
Vestibular / spiral ganglion
Where is the nucleus of CN IX, X, XII?
Medulla
Where is the nucleus of CNXI?
Spinal cord
What is bulbar palsy?
LMN weakness of muscles supplied by cranial nerves that have their nuclei in the medulla (bulb) CN 9, 10 ad 12
Describe the examination findings of bulbar palsy
Tongue: wasted, flaccid and fasiculating, can be moved rapidly
AHH: poor elevation of the soft palate
quiet nasal speech
jaw jerk / gag may be absent
What are the causes of bulbar palsy?
Degenerative (MND) or vascular (stroke) most commonly
Inflammatory - GB rarely
infective - botulism
neoplastic - brainstem tumours
congenital
What is pseudo bulbar palsy?
Bilateral UMN disease of the medullary cranial nerves
What are the examination findings of pseudobulbar palsy?
Tongue: stiff and spastic with slow movements, not wasted
AHH: normal elevation of the soft palate
gravely Donald Duck speech: slurred, high-pitched dysarthria
jaw jerk / gag reflex: preserved, exaggerated jaw jerk
mood disturbances
What are the causes of pseudo bulbar palsy?
Degenerative (MND) and vascular (stroke)
Also seen in MS and can follow head trauma
What is the consequence of lesions in the cerebral hemisphere ?
Impairment of higher function
‘type’s function affected can give clues as to the location affected, but in reality, if there are localising signs, then cranial imaging will be used to localise the lesion
What are the effects of a frontal lobe lesion?
intellectual impairment, personality change, urinary incontinence and mono paresis / hemiparesis
Broca’s aphasia if left frontal area
What are the effects of a left temporo-parietal lesion?
agraphia, Alexia, acalculia
wernicke’s (receptive aphasia)
contralateral sensory neglect
What are the effects of a right temporo-parietal lesion?
Failure of face recognition
Contralateral sensory neglect
What are the effects of an occipital lesion?
Visual field defects, visuospatial defects
Do cerebellar lobes control ipsilateral or contralateral limbs?
IPSILATERAL
What is the function of the vermis?
Maintains midline posture and balance
Describe lateral cerebellar lesion signs
Broad, ataxic fair Titubation dysarthria Nystagmus dysmetric saccades upward drift rebound phenomenon Hypotonia Mild hyporeflexia Dysmetria Dysdiakokinesis
What will midline cerebellar lesions cause?
Rolling, broad and ataxic gait
Difficulty standing and sitting unsupported
Cannot perform Romberg’s test with eyes open or closed
Vertigo and vomiting if extension into the fourth ventricle
What are the common causes of bilateral cerebellar dysfunction?
Alcohol
drugs: phenytoin, anti-epileptics
Paraneoplastic cerebellar degeneration:
Antineuronal antibodies present
Common with breast cancer and small cell lung cancer
Severe hypothyroidism
What are the common causes of unilateral cerebellar dysfunction?
MS
Stroke
Tumour - especially acoustic neuroma, meningioma
What are the structures that make up the basal ganglia?
Corpus striatum: caudate nucleus, globus pallidum and putamen
Subthalamic nucleus
Substantia nigra
Parts of the thalamus
What is the function of the basal ganglia?
Modulate cortical motor activity
What are the signs of basal ganglia disorders?
Bradykinesia
Muscle rigidity
Involuntary movements - tremor, dystonia, athetosis, Chorea, hemiballismus: violent, involuntary movements, restricted to proximal muscles of just one arm
What are the clinical syndromes resulting from basal ganglia pathology?
Parkinsonism
Huntingtons
Hemiballismus
What are the causes of central scotoma?
Macula lesion: diabetic maculpathy
What is the cause of monocular loss of vision?
Ipsilateral optic nerve lesion
What is the cause of bitemporal hemianopia or quadrantanopia?
Optic chiasm lesion
What is the cause of a superior bitemporal quadrantanopia?
Pressure from below the chiasm e.g. pituitary tumour
What is the cause of inferior bitemporal quadrantanopia?
Pressure from above the chiasm e.g. craniopharyngoma, carotid aneurysm, meningioma
What is the cause of a homonymous hemianopia?
Contralateral optic tract lesion
What is the cause of a homonymous quadrantanopia?
Contralateral optic radiation lesion
Temporal lesions give superior homonymous quadrantanopias
Parietal lesions give inferior homonymous hemianopia
PITS
What does macular sparing in homonymous hemianopia signify?
Defect in the visual cortex: occipital lobe
Where is Broca’s area located?
Inferior frontal gyrus, areas 44 and 45
What is the function of Broca’s area?
Motor speech function
What is the function of Wernicke’s area?
Understanding of the spoken word
Where is Wernicke’s area?
Superior temporal gyrus - area 22
What is Broca’s aphasia?
Expressive aphasia:
non-fluent , repetition is poor
What is Wernicke’s aphasia?
receptive aphasia, loss of ability to understand speech
Fluent: normal production of incorrect words
Poor comprehension: poor repetition
What is global aphasia?
Both expressive and receptive dysphasia
What is nominal aphasia?
Difficulty word finding
What is dysarthria?
disordered articulation / slurred speech, language remains in tact
What are the causes of dysarthria?
Bulbar palsy
pseudo bulbar palsy
cerebellar lesions
extrapyramidal lesions: soft, indistinct, monotonous speech
myasthenia gravis: Speech fatigues and dies away
What is Horner’s syndrome?
Oculosympathetic palsy, caused by interruption of the sympathetic chain
Ptosis, miosis and partial anhydrosis
What are the symptoms of a Horner’s syndrome?
Unilateral pupillary constriction (miosis)
Ptosis
Enophthalmos
anhydrosis
What are the causes of a Horner’s syndrome?
First order: 4S: S – Stroke S – Multiple Sclerosis S – Swelling (tumours) S – Syringomyelia (cyst in the spinal cord)
Pre-ganglionic lesions (4 Ts): T – Tumour (Pancoast’s tumour) T – Trauma T – Thyroidectomy T – Top rib (a cervical rib growing above the first rib above the clavicle)
Post-ganglionic lesion (4 Cs): C – Carotid aneurysm C – Carotid artery dissection C – Cavernous sinus thrombosis C – Cluster headache
How does the pattern of anhydrosis help to distinguish first-third order disorders?
Face/arm/trunk anhydrosis: first order
Facial anhydrosis: second order
No anhydrosis: third order
Do LMN innervate ipsilateral or contralateral muscles?
ipsilateral
Do UMN innervate ipsilateral or contralateral muscles?
contralateral
Why do lower motor neurone signs occur the way they do?
loss of trophic effect on muscles
What are the LMN signs?
weakness wasting fasciculation hypotonia hyporeflexia
Why do UMN signs occur the way they do?
Occur due to hyper excitability of inputs to anterior horn cells
what are the UMN signs?
weakness - extensor weakness in upper limbs and flexor weakness in Lower limbs
no wasting hypertonia, spasticity hyperreflexia loss of fine motor movement pronator drift extensor plantar response clonus
What are the ddx for LMN lesions?
ventral horn pathology - MND, post-polio
peripheral nerve pathology
NMJ pathology
Muscular pathology
What are the ddx for UMN lesions?
Vascular: stroke Inflammatory: MS, MND Neoplastic: Tumour Degenerative: Parkinson's Infective: Post-meningitis Extra: drugs
What is the pyramidal pattern of weakness seen in UMN lesions?
Weakness of extensors in upper limbs
weakness of flexors in lower limbs
Why is the frontalis spared in UMN lesions?
Receives innervation from both U and LMN
What are the descending tracts?
MOTOR:
Dorsal and ventral CORTICOSPINAL TRACTS
are the corticospinal tracts contralateral or ipsilateral?
ipsilateral as they decussate in the brainstem
What is the function of the corticospinal tract?
transmit motor axons from the motor cerebral cortex to the spinal spinal cord
What are the ascending tracts?
SENSORY: dorsal columns spinothalamic tract (lateral and ventral)
What is the function of the dorsal columns?
Transmit deep touch, joint position and vibration to the parietal cortex
Are the dorsal columns ipsilateral or contralateral?
ipsilateral - decussate in the brainstem
What is the function of the spinothalamic tract?
transmits pain, temperature and light touch to the thalamus
Is the spinothalamic tract ipsilateral or contralateral?
contralateral
decussates at the spinal level
What clinical syndrome would arise from a cord transection at C3?
Neurogenic shock Respiratory insufficiency Quadriplegia Anaesthesia below the affected level Loss of bladder/bowel sphincter tone Sexual dysfunction Horner's syndrome
What clinical syndrome would arise from a cord transection at T10?
Paraplegia
Anaesthesia below the affected level
Loss of rectal / bladder sphincter tone
Sexual dysfunction
What clinical syndrome would arise from a cord hemisection / BROWN SEQUARD
Ipsilateral reduced power (corticospinal tract), vibration and proprioception (posterior or dorsal column)
contralateral reduced pain / temperature and light touch (spinothalamic tract).
What is the most common cause of a brown sequard syndrome?
Penetrating injury or facet dislocation in a RTA
What is the effect of a posterior cord lesion (loss of dorsal tract)
tingling, numbness, electric shock like syndrome
clumsiness
on examination: sensory ataxia, loss of positional sense, vibration sense and 2-point discrimination below the level of the lesion
what two positions can be used for a lumbar puncture?
lying on their side, curled forward with knees up to their chest to open the lumbar interspinous spaces
(lateral recumbent position)
sitting forward curled into a pillow - especially useful in obese patients
N.B. head must be at the same level as the lumbar spine
Where is the location of LP?
L4
level of the tops of the iliac crest (intercristal plane)
Needle introduced obliquely above L4, parallel to the place of the spine, through the interspinous ligament.
What are the indications of LP?
Diagnosis of meningitis / encephalitis
Diagnosis of SAH - if clinically suspected but no abnormalities on CT
Measurement of CSF pressure: idiopathic intracranial hypertension
therapeutic removal of CSF - idiopathic intracranial hypertension
Intrathecal drug administration
Diagnosis of misc conditions: e.g. MS, neurosyphilis, Behcet’s disease
What are the complications of LP?
Post LP headache - occurs in 30%
Dry tap (poor technique)
Infection
Damage to spinal nerves
Coning of the cerebellar tonsils
What are the contraindications of LP?
Suspicion of mass in the brain / spinal cord or raised ICP
(can lead to coning of the cerebellar tonsils)
Overling / local infection
Congenital lesions in the area
Meningomyelocele
Problems with haemostasis: Platelets <40
Clotting abnormalities
Anticoagulation
Haemodynamic instability
Describe the Post LP headache:
Occurs in 30% - onset within 24 hours, with resolution over 2 weeks
Classically a constant, bilateral dull ache
Worse when upright due to intracranial hypertension
Treat with analgesics +/- blood patch
Re-injection of a patient’s own blood to form a clot
What is xanthocromia?
A yellowish colour of CSF
Caused by bilirubin from RBC breakdown
What does xanthocromia indicate?
That there has been a sub-arachnoid haemorrhage
If the RBCs in the CSF are due to bleeding at the LP site, they will not have been degraded into bilirubin, so CSF will not be xanthocromic
What is the ix for suspected SAH?
CT within 12 hours of onset (diagnoses 98%)
If there is clinical history of SAH but no CT change - lumbar puncture
Important to detect 2% that cannot be seen on CT: sentinel bleeds from aneurysms present like this and severe bleeds can be fatal
What are the CSF findings of MS?
moderately raised protein levels: less than 1g/L
Up to 50 lymphocytes/mm3
oligoclonal IgG bands on electrophoresis
What are the pros and cons of CT head?
pro: rapid procedure - very simple for the patient, good for haemorrhage and calcification
con: Involves ionising radiation
What are the pros and cons of MRI head?
pros: no ionising radiation and can produce superior anatomical detail in the brain
cons: Longer procedure and many patients cannot tolerate the claustrophobic nature of the scanner
What are the contraindications of MRI head?
Electrically, magnetically of mechanically activated implants
Pacemakers, cochlear implants, drug infusion pumps
Implants containing ferrous metals: aneurysm clips, surgical staples
Bullets, shrapnel, metal can all move
?Metallic foreign bodies in the eye
Some implants are now made to be safe for MRI scanners
What is primary brain injury?
Immediate result of a brain trauma
What is secondary brain injury?
Develop later as a result of complications:
hypoxia
ischaemia
haematomas
What is concussion?
Transient loss of consciousness but no persistent neurological signs
temporary confusions of amnesia can occur
there may be signs of neurological injury on CT
What is diffuse axonal injury?
Visible on high resolution CT
number of axons damaged increases with severity of injury
Does not cause raised ICP, and treatment is supportive
What are the consequences of diffuse axonal injury?
Can cause sequelae of deficiencies in higher function
Loss of concentration / memory disturbances
Personality changes
What are focal brain injuries?
Gross damage to localised areas of the brain, visible on CT
Coup injuries: beneath the site of impact
Contre-coup: on the opposite side of the brain, due to rebound of the brain within the skull
haemorrhage / haematoma
Can all act as space-occupying lesions and can result in secondary brain injuries
What is post-concussion syndrome?
dizziness, headache, poor concentration / memory following head injury
inability to work, difficulties with self-care
Physiotherapy and OT may help
Describe the steps to examining a patent with head injury
C-spine precautions
ABCDE resus
A: guedel airway or intubation usually required
Record GCS prior to intubation
B: chest injuries often co-exist and can lead to secondary brain insults
Hypoxaemia is an indication for intubation
C: polytrauma leading to shock
Cross-match as part of vital bloods
Record GCS
Brief history
?seizures
Neurological exam
Imaging: CT head / C-spine radiography
What are the signs of neurological deterioration
Falling GCS - most important sign Changing pupillary size / responsiveness development of focal neurological signs changing respiratory rate Falling pulse, rising BP
Why does pupil size change in neurological deterioration ?
As ICP rises, there is initial progressive dilation on the side of the lesion, and sluggish response to light
This is due to pressure on the oculomotor nerve.
If bilateral, it is a pre-terminal sign
What is Cushing’s reflex?
what is it due to?
Falling pulse, rising BP
due to pressure on the medulla oblongata
more common in younger patients
What is the result of hypercapnia in brain injury?
cerebral vasodilation
Increases cerebral blood volume and thus raises ICP
May be hyperventilated on ICU: reduces PaCo2, vasoconstricts cerebral vessels, decreases ICP
What is the result of hypoxia in brain injury?
can cause cerebral vasodilation
hyperaemia also leads to particularly rapid lactic acidosis within cerebral neurones which causes cerebral damage
What is the MAP normally?
What is the effect o head injury on MAP?
60-160
auto regulation is lost
cerebral blood Flow relies on SBP
As such, resuscitation is vital to maintain SBP
What are the indications for CT after head injury?
1 hour after arrival?
GCS <13 at any time or <15 2 hours after injury Focal neurological deficit Signs of increasing ICP Suspected skull fracture Post-traumatic seizure Vomiting >1 occasion
What are the indications for CT within 8 hours following head injury?
Anticoagulated patients
Loss of consciousness plus: Age >65
Dangerous mechanism of injury (e.g. fall from a great height)
retrograde amnesia >30 minutes
Inability to recall the events immediately before injury
What are the indications to admit following head injury?
If imaging shows pathology
GCS <15
Continuing worrying signs / sources of concern
