DISORDERS OF HIGHER CEREBRAL FUNCTION

Question 1

What is the blood supply to the frontal lobe?

Answer 1

Anterior cerebral artery and the middle cerebral artery. The anterior cerebral artery supplies the medial surface of the primary motor cortex and hence the leg. The middle cerebral artery supplies the lateral surface and hence the face and arms.

Question 2

A lesion in what part of the frontal lobe would cause contralateral weakness?

Answer 2

Pre-central gyrus - causes an upper motor neurone pattern of weakness.

Question 3

A lesion in what part(s) of the frontal lobe would cause gait apraxia? Give a brief definition of gait apraxia.

Answer 3

Pre-motor and supplementary motor area.
It is the inability to walk properly in spite of preservation of normal power, coordination and sensory function, and extrapyramidal dysfunction. The gait is slow and shuffling but upright and wide based, distinct from the flexed posture of Parkinsonian gait.

Question 4

What are the features of focal seizures in the frontal lobe?

Answer 4

Clonic movements of the contralateral lower face, arm and leg
Conjugate deviation of the head and eye towards the convulsing side (i.e. away from the lesion)

Question 5

A lesion in what part of the frontal lobe would cause anosmia? Give a brief definition of anosmia.

Answer 5

Lesions of the inferior or orbital frontal lobes can be accompanied by disturbances of the olfactory pathway and optic nerves as a result of close proximity of these pathways. Anosmia is an inability to smell.

Question 6

A lesion in which lobe of the brain would cause urinary incontinence?

Answer 6

Frontal lobe

Question 7

What is the blood to the parietal lobe?

Answer 7

Middle cerebral artery

Question 8

What is astereognosis?

Answer 8

The inability to identify an object by active touch of the hands without other sensory input.

Question 9

A lesion is which lobe causes a contralateral homonymous inferior quadrantanopia?

Answer 9

Parietal

Question 10

What is Wernicke’s dysphasia?

Answer 10

Impaired comprehension of speech and written language. Speech is fluent but does not make sense. Patient has poor insight into the problem.

Question 11

A lesion in one of which two lobes of the brain can cause Wernicke’s dysphasia?

Answer 11

Inferior parietal (dominant)
Superior temporal (dominant)

Question 12

What is Gerstmann’s syndrome?

Answer 12

Consists of the inability to differentiate the right and left sides of the body, inability to distinguish fingers of the hand (finger agnosia) and impairment of calculation (dyscalculia) and writing (dysgraphia). Lesions in the dominant parietal lobe will lead to the develop of one or more of these symptoms.

Question 13

What is bilateral ideomotor and ideational apraxia?

Answer 13

Inability to carry out a sequence of tasks when there is normal comprehension and intact motor and sensory function. Results from a lesion in the dominant parietal lobe.

Question 14

What is contralateral sensory inattention?

Answer 14

An inability to perceive a contralateral stimulus when two simultaneous sensory stimuli are applied with equal intensity to corresponding sites on opposite sides of the body. Unilateral application of the stimulus is perceived. This inattention can be motor, sensory or visual. Results from a lesion of the non-dominant parietal lobe.

Question 15

What is constructional apraxia?

Answer 15

Difficulty drawing simple objects or difficulty construction simple objects. Results from a lesion of the non-dominant parietal lobe.

Question 16

What is dressing apraxia?

Answer 16

Inability to put on clothes. Results from a lesion of the non-dominant parietal lobe.

Question 17

What is topographical disorientation (topographagnosia)?

Answer 17

Patients cannot find his or her way around normally familiar spaces.

Question 18

What are the visual disturbances associated with lesions of the temporal lobe?

Answer 18

Superior homonymous quadrantanopia

Question 19

A lesion in which lobe in the brain is associated with memory impairment?

Answer 19

Medial temporal lobe involving the hippocampus and parahippocampal gyrus.

Question 20

With regard to memory impairment as a result of lesions in the parietal lobes, which lobe will be associated with the learning of verbal information?

Answer 20

The dominant lobe (most often the left)

Question 21

A lesion in which lobe in the brain is associated with emotional disturbances?

Answer 21

The limbic system is part of the parietal lobe. There are parts of the limbic system that are subcortical.

Question 22

What is auditory agnosia?

Answer 22

The inability to recognise sounds. Results from lesions of the non-dominant temporal lobe.

Question 23

A lesion in which lobe(s) in the brain is associated with cortical deafness?

Answer 23

This occurs only with bilateral lesions of the primary auditory cortices in the temporal lobes and as such is very rare.

Question 24

What is global dysphasia?

Answer 24

Lesions to both Broca’s and Wernicke’s area leads to loss of fluent speech and impaired comprehension of language. This is the most common type of dysphasia and is usually caused by a stroke affecting the left middle cerebral artery.

Question 25

What is the blood supply to the occipital lobe of the brain?

Answer 25

Posterior cerebral artery

Occipital poles, subserving macular vision, have additional supply from a branch of the middle cerebral artery.

Question 26

A lesion of which lobe and artery causes contralateral homonymous hemianopic field defects?

Answer 26

Lesion of the posterior cerebral artery and hence occipital lobe

Question 27

A lesion in which lobe(s) in the brain is associated with cortical blindness?

Answer 27

Bilateral occipital lesions render the patient blind, with retention of the pupillary reflexes.

Question 28

What is Anton’s syndrome?

Answer 28

Patient deny’s being blind despite cortical blindness.

Question 29

What is visual agnosia?

Answer 29

Lesions of the visual association cortices cause impairment of perception or identification of faces and objects even though visual acuity and fields are normal.

Question 30

What is achromatopsia?

Answer 30

Inability to distinguish different colours.

Question 31

What is prosopagnosia?

Answer 31

Inability to recognise human faces.