Neuroanatomy concepts and conditions

What is the Circle of Willis, and why is it important?

It is a connected ring of arteries that allows blood flow to be redirected if another vessel is damaged

What are the three major cerebral arteries you need to know?

• ACA → frontal and parietal areas

• MCA → parietal, temporal, and sensorimotor areas

• PCA → occipital lobe and other structures including the thalamus and hippocampus

Why is the MCA especially important when studying stroke?

It is the most commonly impacted artery in ischemic stroke and affects the upper limbs and face more than the lower limbs

What are the two major types of stroke?

Ischemic and hemorrhagic strokes.

What causes an ischemic stroke?

A blood clot blocks blood flow to part of the brain. The clot may be a thrombus that stays in place or an embolus that travels.

What causes a hemorrhagic stroke?

A blood vessel, often because of an aneurysm, ruptures and causes bleeding into or around the brain.

What are common signs of a stroke?

These symptoms can immediately affect a person's ability to safely complete ADLs, mobility, communication, work, and leisure activities.

What are common effects of a right hemisphere stroke?

• Left hemiplegia/hemiparesis

• Left-sided neglect

• Sensory and vision changes

• Dysarthria

• Impulsivity

• Poor judgment

• Short-term memory loss

• Agnosia

What are common effects of a left hemisphere stroke?

• Right hemiplegia/hemiparesis

• Sensory and visual changes

• Aphasia

• Impaired reasoning

• Difficulty planning and organizing

• Difficulty reading, writing, and math

• Difficulty with new learning

What is hemispatial neglect?

Lack of awareness of stimuli on one side of the body or environment. It is more common after a right-sided CVA.

Is neglect the same thing as losing sensory information?

No. Neglect involves a lack of awareness of stimuli rather than simply losing sensory information.

What is agnosia?

The inability to recognize or identify something.

What is visual agnosia?

Difficulty recognizing objects through vision.

What is prosopagnosia?

Difficulty recognizing familiar people or faces.

What is anosognosia?

Lack of awareness or denial of one's physical or cognitive impairment.

What is hemianopsia?

Loss of vision in half of the visual field

What is quadrantanopsia?

Loss of vision in one-quarter of the visual field.

Why might visual field loss be difficult to notice?

The brain can try to fill in familiar images, so the person may compensate without realizing they have a visual field deficit.

What are the major effects of an MCA stroke?

• Contralateral hemiplegia/hemiparesis

• Sensory loss

• Upper limb and face more affected

• Homonymous hemianopia

What are the major effects of an ACA stroke?

• Contralateral hemiplegia/hemiparesis

• Lower limbs more affected

• Personality changes

• Bladder/bowel control problems

What are the major effects of a PCA stroke?

• Visual field loss

• Memory loss

• Possible oculomotor problems

• Sensory changes/pain

Why are vertebrobasilar strokes particularly serious?

They affect the brainstem and cerebellum and can cause ataxia, balance problems, swallowing dysfunction, dysarthria, vertigo, sensory loss, quadriplegia, locked-in syndrome, or coma.

What are common signs of increased ICP (intracranial pressure)?

• Headache

• Nausea/vomiting

• Drowsiness

• Gait ataxia

• Eye movement problems

What is cerebral edema?

Accumulation of fluid in and around the brain that increases ICP.

Why is brain herniation an emergency?

Increasing pressure can compress brain structures, and brain herniation is life-threatening.

What is the blood-brain barrier (BBB)?

A permeability barrier between blood vessels and CNS structures that limits harmful or large molecules from entering the brain.

Why can the BBB be both helpful and limiting?

It protects the brain from harmful substances but can also prevent some medications from reaching CNS structures.

What are three functions of CSF?

• Regulates substances

• Removes waste

• Cushions and protects the brain

What are the three meninges?

• Dura mater – outer layer

• Arachnoid – middle layer

• Pia mater – inner layer

What is a hematoma?

A pooling of blood within the layers of the meninges.

Where is an epidural hematoma located?

Between the skull and dura mater.

Where is a subdural hematoma located?

Between the dura mater and arachnoid layer.

What is a TIA?

A brief change in neurological function, sometimes called a “mini stroke,” where symptoms resolve within 24 hours.

A client has a right-sided CVA. What occupational performance problems would you expect?

Left-sided weakness, left neglect, visual changes, impulsivity, poor judgment, and possible memory problems.

A client with a left-sided CVA is having difficulty communicating and following a written recipe. What deficits might explain this?

Aphasia and possible difficulty with reading, planning, organization, or new learning.

A client repeatedly leaves food on the left side of their plate after a right-sided stroke. What impairment should you suspect?

Left hemispatial neglect.

A client has weakness primarily affecting their arm and face following a stroke. Which artery should you consider?

MCA. The MCA affects the upper limb and face more than the lower limb.

A client has significant balance problems, vertigo, dysarthria, and swallowing difficulties after a stroke. What area/vessel might be involved?

The vertebrobasilar system, which supplies the brainstem and cerebellum.

The vertebrobasilar system, which supplies the brainstem and cerebellum.

Because the location of the injury helps the OT anticipate potential motor, sensory, cognitive, visual, communication, and behavioral impairments and understand how they may affect occupational performance.