headache Flashcards
the CNS is derived from what embryonic layer?
ectoderm
during early development of the CNS 3 primary vesicles arise then 5 secondary vesicles -forebrain (telencephalon and diencephalon), midbrain (mesencephalon) and hindbrain (metencephalon and myelencephalon) - what are the adult derivatives of these secondary structures?
telencephalon:
= cerebral hemispheres with later ventricles
diencephalon:
= thalamus and 3rd ventricle
mesencephalon:
= midbrain and cerebral aqueduct
metencephalon:
=pons, cerebellum and 4th ventricle
myelencephalon:
= medulla and 4th ventricle
what layer does nerve cell migration start and finish?
ventricular zone to cortex
what cells do nerve utilize for migration. what condition arises if this transport system doesn’t work?
radioglial cells
epilepsy
what cell is responsible for myelinating neurons in the CNS and PNS, how do they differ?
CNS = oligodendrocytes
PNS = Schwann cells
*oligodendrocytes secrete myelin sheaths around many neurons. Schwann cells wrap their cell body around each neuron separately
T or F. A brainstem lesion will usually produce ipsilateral cranial nerve defect
True
*exception = trochlear nerve: axons cross in midline
what CNs arise from the midbrain, pons and medulla?
midbrain = oculomotor and trochlear
pons = trigeminal, abducens, facial, vestibulocochlear
medulla = glossopharyngeal, vagus, accessory and hypoglossal
what condition is caused by damage to the sympathetic innervation to the face?
a brainstem lesion will produce an ipsilateral Horner’s syndrome: miosis, ptosis, and anhidrosis (absence of sweating of the face)
what ascending (sensory) white matter tract is responsible for pain, temperature, touch and pressure? where do fibres cross and what is the consequence of this?
spinothalamic tract, decussates early so are susceptible to central cord pathology
what ascending (sensory) white matter tract is responsible for touch vibration and proprioception? where does it cross?
dorsal column-medial lemniscal pathway. crosses in the medulla
why is the pathway for light touch sensation unique?
Not specific to one pathway. it travels with both the spinothalamic tract and the dorsal column-medial lemniscal tract
what conditions may affect the dorsal spinal cord?
- vitamin B12 deficiency (subacute combined degeneration of the spinal cord)
- MS
- HIV myelopathy
there are two columns in the dorsal-column medial lemniscus pathway that transmit information from the upper and lower limbs. what are they?
the cuneate column transmits information from the upper limb, neck and trunk.
the gracilis column transmits information from the lower limbs
what pathway is ipsilateral and controls coordination?
spinocerebellar tract
unconscious proprioception
what major descending (motor) white matter tract is responsible for movement by innervating skeletal muscles? where does it cross?
corticospinal tract. crosses in the medulla (ventral pyramids)
what is the difference between a pre-motor lesion and a primary motor area lesion?
if the primary motor cortex is destroyed you have a complete weakness and hemiplesia
if the premotor area is destroyed (controls higher functions of movement) you get apraxia - difficulty with motor planning
the motor system as a whole integrates information from different modalities, in the parietal cortex, to focus attention on relevant target and/or upon the spatial relationships of objects. what are these modalities?
- somatic sensory area (about limb position)
- vestibular system (about head position)
- premotor areas (about motor plans)
- visual system
- limbic cortex (about motivational state
what are the 3 major sources of input into the corticospinal tract that fine tune movement?
- sensory receptors
- cerebellum
- basal ganglia
compare and contrast upper and lower motor neuron lesions?
UMN vs LMN:
- weakness = present both (UMN: arm extensors and led flexors)
- atrophy = absent vs present
- reflexes = increased vs decreased
- tone = increased vs decreased
- fasciculations = absent vs present
- Babinski (extension of toes) = present vs absent
where is CSF produced, what is its pathway and where is it reabsorbed?
- produced by choroid plexus in lateral ventricles
- travels down 3rd ventricle -> cerebral aqueduct -> 4th ventricle -> spinal cord or surround brain (via foramen of Luschka or foramen of Magende
- reabsorbed in arachnoid granulations in venous sinuses (drain brain into internal jugular veins)
what would you expect to see in CSF from lumbar puncture?
- virtually no proteins <0.5mg/ml
- no RBC
- <5 WBC/m
- glucose 60-70% blood levels (2.5-5mmol)
when should you never carry out/ what are the contraindications of LP?
**if there is any possibility of space occupying lesion!! (risk of coning)
- cardiorespiratory instability
- focal neurological signs
- signs of ICP (coma, high BP, low HR or papilloedema)
- coagulopathy
- local infection at site of LP
what is the normal opening pressure of CSF and when is it considered elevated?
<20cm water, elevated >30cm
what happens if CSF flow is blocked (congenital aqueduct stenosis, infection, inflammation, tumours, idiopathic intracranial hypertension etc.)?
- fontanelle unfused = hydrocephalus with expanded cranium
- fontanelle fused = can be normal if occurs slowly, but if fast can cause ICP, drowsiness and coma
what are the features of a low pressure headache?
- eased on lying down, worse standing up
- can occur spontaneously, but usually post LP
clinical presentation of meningitis - inflammation of the meninges
- stiff neck
- petechial rash (non-blanching), progressive is suggestive of meningococcal infection
- bulging fontanelle
- photophobia
- fever
- headache (severe + generalised)
- altered mental state (confusion/lethargy)
- +ve brudzinski and kernig sign
investigation of meningitis
LP:
- bacterial= glucose low, protein raised, neutrophils raised, cloudy
- viral= glucose normal, raised proteins, lymphocytes raised, clear
CT if suspect contraindications of LP
FBC:
-shows infection, but not where
coagulation screen:
-check can clot okay
Management of meningitis
- ABC
- haemodynamically stable (e.g. shock = hypotension)
- fluid balance
- electrolyte balance
- start antibiotics -> CEFOTAXIME IV 2g immediately 12-hourly (if pt >50 y/o, pregnant, immunocompromised or on steroids, add amoxicillin 2g every 6 hours to provide Listeria cover)
- steroid - dexamethasone 0.15g/kg 6-hourly
-prophylaxes family with ciprofloxacin
Clinical presentation of brain abscess - focal, intracerebral infection evolving from an area of cerebritis into a collection of purulent material enveloped in a vascularized capsule
*caused by direct or indirect spread from infection in paranasal sinuses, middle ear and teeth
- vomiting
- bulging fontanelle
- increased head circumference
- separation of sutures
- hemiparesis
- focal seizures
- increased WBC count
- can occur with neonatal meningitis
investigation of brain abscess
- CBC: raised WBC!
- serum erythrocyte sedimentation rate (ESR): elevated
- MRI/CT
management of brain abscess
(broad spectrum)Cefotaxime IV 2-4g 8-hourly + metronidazole IV 500mg 8-hourly
drainage of abscess