Neuroscience Exam 2

3 meninges

dura matter

arachnoid matter

pia matter

Dura Mater

2 layers: periosteal layer and meningeal layer

Between the 2 layers are venous sinuses

2 folds: Falx cerebri and tentorium cerebelli

Arachnoid mater

thin weblike middle layer of the three meninges

Pia Mater

Innermost layer of the meninges, follows the contour of the brain

3 spaces of meninges

epidural space, subdural space, subarachnoid space

Falx Cerebri

separates R and L hemispheres

runs in the longitudinal fissure

tentorium cerebelli

separates occipital and temporal lobes from the cerebellum and parts of the brain stem

runs horizontally

Epidural Space

between skull and dura matter

contains: middle meningeal artery

implications: rupture of middle meningeal artery (epidural hematoma)

Middle meningeal artery

What vessel is lacerated in an epidural hematoma (generally caused by a temporal bone fracture, contains oxygenated blood)?

Subdural space

between dura mater and arachnoid mater

contains: bridging veins that drain into venous system

implications: rupture of bridging veins

subdural hematoma

-a rupture of bridging veins

-susceptible to shearing forces

-commonly seen in older adults

Subarachnoid space

Between arachnoid mater and pia mater

contains: CSF major arteries

implications: subarachnoid hematoma

Subarachnoid hematoma

Traumatic: falls or MVA

Non-traumatic: arteriovenous malformations, aneurysm

Hemorrhage in arteries cause bleeding into the CSF

Presentation: severe headache

Non-traumatic injury in subarachnoid space

AV malformation

Aneurysms

AV malformation

congenital, the normal capillary bed that exists between the artery and venous circulation fails to develop in one part of the brain and exist as a mass of thin-walled vessels carrying blood at arterial pressure. These can rupture, causing subarachnoid hemmorage

aneurysm

an excessive localized enlargement of an artery caused by a weakening of the artery wall.

venous sinuses

located between the 2 dural layers (periosteal and meningeal)

deoxygenated blood gets transported through here

Implications for OT

-neuro checks min every 72 hrs

-frequent neurological assessments

-assess vital signs, pupillary size, reactivity, grip strength, Glasgow Coma Scale done immediately and once each shift

Meningitis

inflammation of the meninges

young and immunocompromised at risk

signs: headache, lethargy, sensitive to light and noise, fever, nuchal rigidity

13-15 mm HG

Normal adult intracranial pressure

facilitates blood perfusion

3-7 mm Hg

normal child intracranial pressure

hydrocephalus

-caused by:

1. excess production of CSF

2. obstruction: common foramen of Monroe, cerebral aquaduct, 4th ventricle

3. decrease inreabsortion

-Greater than 135-150 ml of CSF will cause __ and herniation of the brain structures that can limit blood perfusion

obstructive hydrocephalus

non-communicating, CSF is blocked along one or more narrow passages connecting the ventricles

Communicating hydrocephalus

flow of CSF blocked after it exits the ventricles

decrease in absorption

Normal pressure hydrocephalus

a condition sometimes seen in elderly patients characterized by chronically dilated ventricles

CSF Circulation

1. CSF produced in choroid plexus flows to lateral ventricles via foramen of Monroe

2. Flows to 3rd ventricle via Sylvian aqueduct

3. flows to 4th ventricle via foramen of Luschka and Magendie

4. Cistern and subarachnoid space

5. reabsorbed by arachnoid granulations

6. exits through venous sinuses to go back to the heart

arachnoid villi granulations

reabsorbs CSF into the venous sinus blood supply

functions of CSF

buoyancy

protection

chemical stability

prevents brain ischemia

Causes of increased intracranial pressure

hydrocephalus

tumors

hemorrages

cerebral edema

obstruction of venous flow

Signs and symptoms of ICP

-Headache

-Altered mental status: irritability, depressed level of alertness and attention

-Nausea and vomiting

-Papilledema

-visual loss

-diplopia

-cushing's triad

-LE weakness

-corticobulbar signs

-unsteady gait

-falls

-incontinence

Ventricular Peritoneal shunt

medical intervention to normalize ICP

Device to drain excess cerebrospinal fluid.

OTs responsibility with patients with ICP

know the signs and symptoms

unique symptoms that therapists should recognize: problems with gait and LE weakness

seek medical help ASAP

Circle of Willis

A circle of arteries at the base of the brain that supply blood to the brain

Anterior Circulation

internal carotid arteries

anterior cerebral arteries

middle cerebral arteries

anterior communication artery

posterior communicating arteries

Posterior circulation

vertebral arteries

posterior inferior cerebellar arteries

basilar artery

anterior inferior cerebellar arteries

superior cerebellar arteries

posterior cerebral arteries

Anterior and Posterior Communicating Arteries

arteries key to forming the Circle of Willis

anterior cerebral artery

supply cortex of anterior/medial from frontal to anterior parietal lobe

posterior cerebral artery

supply inferior and medial temporal lobe, occipital lobe, and thalamus

Anterior Spinal Arteries

Supplies anterior 2/3 of spinal cord

control anterior and lateral spinal cord tract

Posterior Spinal arteries

supply posterior 1/3 of spinal cord

Hemorrhagic stroke

-15-20%

-rupture of a blood vessel - intracerebral or subarachnoid hemorrhage

-causes: ruptured aneurysm, arterio-venous malformation, trauma to the head

Ischemic Stroke

-80-85%

-lack of blood supply or complete blockage of blood supply

-antidote: tissue plasminogen activator

thrombus

-slow occurring clot due to a build up of blood factors

-slow onset

embolism

-blockage by a clot or foreign material brought to its site, by the dislodgment by blood

-sudden

Transient Ischemic Attack

-events caused by changes in lack of arterial blood vessels causing brief periods of neurologic changes

-followed by complete recovery in most cases

BE FAST

B: balance

E: eyes: diplopia

F: facial drooping

A: arm weakness, numbness in hands or feet

S: slurred speech

T: time to call 911 or terrible headace

2/3 of strokes

occur in MCA (middle cerebral artery)

Superior Division of MCA

-Supplies cortex above sylvian fissure

-brain centers affected: Broca's, primary motor and primary sensory cortex

Inferior Division of MCA

supplies the cortex below the Sylvian Fissure

brain centers: primary auditory cortex, Wernicke's

Deep territory of MCA

-Lenticulostriate arteries

-supply the basal ganglia

Superior Division Left CVA

-UMN-type right face and arm weakness

-non-fluent Broca's aphasia

-Some cortical sensory loss of right arm and face

Superior MCA Division Right CVA

-UMN type: left face and arm weakness

-left hemi-neglect (variable)

-some left arm and face cortical sensory loss

Inferior MCA division L CVA

-Wernicke's aphasia/ fluent aphasia

-Right visual field deficit (contralateral hemianopsia)

-Motor findings absent

-On close exam, may find slight R sided weakness at onset

Inferior MCA division R CVA

-profound hemi-neglect

-motor neglect with decreased voluntary or spontaneous movement on L side, even w normal strength

-L visual field deficit (contralateral hemianopsia)

-R gaze preference

-somatosensory deficits

-mild L side weakness

Deep Territory MCA L CVA

-lacunar stroke

-Right pure motor hemiparesis UMN type

-large infarct may produce cortical type deficits such as aphasia and hemiplegia

Deep Territory MCA R CVA

-left pure motor hemiparesis

-larger infarcts may produce cortical type deficits such as left hemi-neglect

L Brainstem CVA

-R hemiplegia, hemianesthesia, homonymous hemianopsia

-global aphasia

-L gaze preference

-caused by damage to L hemisphere cortical areas, important for driving the eyes to the right

R Brainstem CVA

-L hemiplegia, hemianesthesia, homonymous hemianopsia

-profound hemineglect

-R gaze preference

-caused by damage to R hemisphere cortical areas important for driving eyes to the left

L ACA stroke

-R leg hemiplegia/weakness

-larger infarcts = R hemiplegia

-R leg cortical type sensory loss

-frontal lobe behavioral abnormalities: abulia, disinhibition, executive dysfunction, grasp reflex, transcortical aphasia

R ACA stroke

-L leg hemiplegia/weakness

-larger infarcts = L hemiplegia

-L leg cortical type sensory loss

-frontal lobe behavioral abnormalities and primitive reflexes (grasp reflex)

-Some L hemi-neglect

L PCA stroke

-R homonymous hemianopsia

-lesion affecting splenium of corpus collosum can cause alexia without agraphia

-larger infarct = impacts thalamus and internal capsule can cause hemianesthesia and hemiplegia

R PCA stroke

-L homonymous hemianopsia

-larger infarct = impacts thalamus and internal capsule and can cause hemianesthesia and hemiplegia

Dorsal column medial lemniscal tract

an ascending somatic sensory pathway that mediates information about proprioception, vibration, fine touch, light touch, 2 point discrimination, stereognosis, graphesthesia

in dorsal column medial lemniscus tract, 1st order neuron synapse here

nucleus gracilis or nucleus cuneatus

in dorsal column medial lemniscus tract, 2nd order neuron synapse here

ventral posterior lateral (VPL) nucleus (thalamus)

Caudal medulla

-level of decussation of DCML tract

-2nd order neurons decussate as internal arcuate fibers and form the pons and midbrain (medial lemniscus)

Test for light touch

eyes closed, touch cotton ball (proximal to distal), asking if they were touched

2 point discrimination

ability to distinguish the separation of 2 simultaneous pinpricks on the skin

Moberg Pick Up test

test for stereognosis

DCML tract lesion 1st order neuron

ipsilateral deficits (below decussation)

DCML tract lesion 2nd order neuron (below decussation)

-lesion in nucleus gracilis or cunneatus

-ipsilateral deficits

DCML tract lesion 2nd order neuron (above decussation)

-happens at caudal medulla

-contralateral deficits

DCML tract lesion 3rd order neuron

-contralateral deficits

-above decussation

Transverse Cord syndrome

cause: trauma, tumor, MS, transverse myelitis

-all pathways partially or completely interrupted

-deficits: sensory and motor pathways are diminished below the level of lesion (both sides)

-discriminative and protective sensation loss

-weakness/paralysis and reflex loss

Brown Sequard syndrome

cause: knife wounds, MS, lateral compression, tumors

deficits:

-lateral corticospinal spinal tracts: ipsilateral UMN type weakness below level of lesion, ipsilateral LMN atrophy, fasciculations at site of lesion

-DCML tract: ipsilateral loss of vibration, position sensation below level of lesion

-ALS- contralateral loss of pain and temp, beginning one to two segments below the level of lesion

-may also have ipsilateral loss of pain and temp (1 or 2 segments higher)

Central Cord Syndrome

-causes: hyperextension injury of the cervical spine leading to spinal cord impingement resulting in central hemorrhaging, syringomyelia

-small lesion: ALS: loss of B pain and temp at level of lesion, cervical cord: cape distribution

-large lesion: lateral corticospinal tracts: UMN lesion, B below the lesion, UEs > LEs

-ventral anterior horn cells: LMN type of lesion at level of lesion - B

-Anterolateral spoinothalamic tracts: B below the lesion

Anterior Cord Syndrome

causes: ischemia of anterior spinal artery, MS

Deficits: B ALS - loss of pain, temp, touch below the level of lesion, ventral horns: LMN types of weakness at level of lesion

Large lesion: B LCS -UMN symptoms below the level of lesion

-autonomic function: neurogenic bladder, hypotension, sexual dysfunction

Posterior Cord syndrome

-causes: posterior spinal artery occlusion, trauma, posteriorly located tumors, MS, B12 deficiency, advanced syphilis

-deficits:

-DCML tract: ipsilateral loss of vibration and position sense below the level of lesion

-Large lesion: lateral corticospinal.tract: UMN type weakness

primary sources of blood to the brain

internal carotid and vertebral artery

internal carotid

The anterior circulation making up the circle of willis is supplied by which artery?

vertebral artery

Supplies blood to the posterior brain.

anterior cerebral artery

supplies frontal lobe

middle cerebral artery

Supplies lateral aspects of the cerebral hemispheres.

posterior communicating artery

The artery of the Circle of Willis that transports

blood from the internal carotid artery to the

posterior cerebral artery is the

posterior cerebral artery

supplies occipital lobe and thalamus

lenticular striate arteries

supply basal ganglia

anterior spinal artery

supplies 2/3 of spinal column

posterior spinal arterise

supplies 1/3 of the spinal column

anterior communicating artery

connects right and left anterior cerebral arteries

posterior communicating arteries (2)

connect the posterior cerebral arteries to the middle cerebral arteries.

test for ACA stroke

frontal release signs

gracile fasciculus

sensations of limb and trunk position and movement, deep touch, visceral pain, and vibration, and discriminative touch level T6 and below

-at L1 you should only see this

cuneate fasciculus

carries sensations of movement, deep touch, visceral pain and vibration above T6

ventral horn

motor neurons

dorsal horn

sensory neurons

intermediate horn

• autonomic nervous system neurons

• unconscious proprioception neurons

POSTERIOR CEREBRAL ARTERY

-thalamus: pure hemianesthesia

-occipital lobe

-implications: homonymous hemianopsia

-testing: visual field testing

ANTERIOR CEREBRAL ARTERY

-prefrontal cortex

-transcortical aphasia (can repeat words, but difficulty with spontaneous speech

-motor loss of LEs and trunk

-cortical type sensory loss (discriminative)

MIDDLE CEREBRAL ARTERY

-brain centers and function affected by individual artery lesions and a collective lesion

-Left side: Broca and Wernicke's area

-Motor and sensory cortex

-Optic radiations (homonymous hemianopsia)

-Basal ganglia

-R superior and inferior division - hemineglect and gaze preference

-Secondary association areas

Brainstem stroke

-supplied by vertebral and basilar arteries

-worse prognosis

-involves venters that control vital signs

-characterized by diplopia, dysphagia, dysarhria, dizziness