Section 4 - Meninges Flashcards
Why can space-occupying lesions be traumatic?
Meninges are very durable, but increase in brain volume can compress healthy tissue.
What is a congenital dermal sinus?
Failure of ectoderm to pinch off from the neuroectoderm and meninges; commonly causes recurrent meningitis
What can cause an extradural (epidural) hematoma?
Head trauma - periosteal dura can loosen and damage middle meningeal artery or accessory meningeal artery
What happen in an epidural hematoma?
Extravascular blood dissects periosteal dura from skull - epidural hematoma. Looks SHORT AND WIDE.
What are symptoms of an epidural hematoma?
- Similar to increase in ICP (headache, disorientation, confusion, lethargy, unresponsiveness)
What is Talk and Die syndrome?
Patient is initially rendered unconscious. He/she has a lucid interval (awake and conversant), but then deteriorates and dies suddenly. Happens with EPIDURAL HEMATOMA.
What is a dural border / subdural hematoma?
Bleeding below meningeal dura within dural border cell layer (adjacent to arachnoid) –> cell layer splits and creates space at dura-arachnoid interface. LONG AND THIN hematoma.
What causes a dural border / subdural hematoma?
Typically, bleeding from a bridging vein passing through subarachnoid space to enter venous sinus.
Acute subdural hematoma is caused by:
Chronic subdural hematoma is caused by:
- hemorrhage or contusion
- brain atrophy with chronic bleeds (elderly)
What is a hygroma?
Tearing of arachnoid membrane due to skull trauma causes the CSF to dissect and open dural border cell layer
What causes a subdural hematoma?
Head trauma shifts the brain enough to tear a large vein before in enters the sinus OR hemorrhage of vessels within the subarachnoid space.
- Blood can migrate to cisterns or outline brain divisions or dural reflections
What is the main sign of a subarachnoid hematoma?
Blood in the CSF
A nontraumatic or spontaneous subarachnoid hemorrhage is caused by:
Rupture of intracranial aneurysm
A primary aneurysm is:
A secondary aneurysm is:
- one dilated from birth
- one dilated by systemic problems (hypertension)
List symptoms of aneurysm rupture:
- THUNDERCLAP HEADACHE
- neck stiffness
- vomiting/nausea
- depression
- loss of consciousness
List warning signs of an impending subarachnoid hemorrhage (leaking aneurysm):
- Intermittent headache
- Nausea/vomiting
- Fainting spells (syncope)
What is a duret hemorrhage?
Small, linear bleeding in ventral/paramedial brainstem (pons and medulla) from traumatic downward displacement of brainstem.
What is a herniation syndrome?
Intracranial event (hemorrhage, rapid tumor growth, traumatic brain injury) that causes increased intracranial pressure by forcing brain over the edge of a dural reflection.
Subfalcine or cingulate herniation:
supratentorial
Lesion in one cerebral hemisphere may expand toward midline, deform falx cerebri, force cingulate gyrus under edge of falx into opposite hemisphere
Subfalcine/cingulate herniation reflects deficits of ______
Occlusion of anterior cerebral artery
Central (transtentorial) herniation:
supratentorial
Diencephalon forced downward through tentorial incisures or notch into the brainstem.
Central (transtentorial) herniation causes:
Change in respiration, loss of motor/sensory function, loss of consciousness, 90% serious disability/death. EMERGENCY.
Uncal herniation:
supratentorial
Rapidly expanding lesion forces uncus over edge of tentorium cerebelli –> midbrain damage.
What are consequences of uncal herniation?
- Decreased level of consciousness
- Dilation of pupil and loss of eye movement (CN III ipsilateral)
- Contralateral hemiplegia (corticospinal fibers)
- Abnormal reflexes
CLINICAL TRIAD:
- unresponsive pupil (CN III)
- Hemiplegia (cerebral peduncles)
- Coma (midbrain reticular formation)
Sphenoidal herniation:
supratentorial
Displacement of ventral frontal lobar tissue over sphenoid ridge
Subfalcial herniation:
supratentorial
Beneath the falx cerebri, usually of the cingulate gyrus
Upward cerebellar herniation:
infratentorial
Pressure increase in posterior fossa forces cerebellum upward through tentorial incisura –> damage midbrain, occlude SCA (infarct cerebellar things), obstruct cerebral aquedect (hydrocephalus)
Tonsillar herniation:
infratentorial
Tonsils of cerebellum forced downward (pressure in posterior fossa) through foramen magnum.
Effects of tonsillar herniation?
- Pressure on medulla in ventrolateral reticular area –> respiratory/cardiac centers damaged, leading to death (Cheyne-Strokes respiration, hypertension, hyperventilation, loss of consciousness)
Closed head injury can cause ______
Concussion/contusion on brain –> momentary loss of consciousness. Brain is on trabecular tethers and can move from sudden blow. Injury either at point of blow or contrecoup.
What is a meningioma?
Slow-growing, benign tumor (potentially calcified) that can result from abnormal growth of adjacent bone. Surgical removal preferred.
What typically gives rise to meningiomas?
Arachnoid cap cells in the villi along base of skull
Neurofibromatosis associated with multiple meningiomas may also have ______
bilateral vestibular schwannomas
Symptoms of meningioma:
- CN abnormalities
- Edema
- Brain structure compression - seizures, personality or behavioral changes, long tract involvement
If lumbar cistern not accessible, how can CSF be examine?
Needle insertion through atlantooccipital membrane to cisterna magna.
Where does bacterial meningitis normally start? (site of infection)
Subarachnoid space (leptomeningitis for arachnoid and pia; pachymeningitis for dura)
Symptoms of acute bacterial meningitis:
- Elevated temp
- Fever alternation
- Headache
- Photophobia
- Depressed consciousness
- Nuchal rigidity
- Increased CSF pressure, cloudy (WBC), increased protin, bacteria
- Hydrocephalus
Symptoms of chronic bacterial meningitis:
(TB or fungal infection)
- Headache
- Fever
- Irritability
- Wakefulness at night
What is Kernig’s sign?
One of the physically demonstrable symptoms of meningitis is Kernig’s sign. Severe stiffness of the hamstrings causes an inability to straighten the leg when the hip is flexed to 90 degrees. (This would hurt me normally, so idk what that says about me).
What is Brudzinski’s sign?
One of the physically demonstrable symptoms of meningitis is Brudzinski’s sign. Severe neck stiffness causes a patient’s hips and knees to flex when the neck is flexed.
Symptoms of viral meningitis:
- Usually younger patients (no antivirals available)
- Fever
- Headaches of increasing intensity
- Confusion
- Altered consciousness
- Seizures
- Rigidity
- Cranial nerve palsies
What can lead to arterial blood in the cavernous sinus?
Congenital aneurysm or arteriovenous malformation in internal carotid OR basilar skull fracture can lead to arterial blood in cavernous sinus.
What are symptoms of arterial blood in cavernous sinus?
- Venous congestion (chemosis) of the eye
- Exophthalmos
- Pulsations (pulsating exophthalmos)
- Compression of related nerves (3, 4, 6, V1, V2)
