Disorders

Question 1

Strabismus

Answer 1

• Symptoms:

Misalignment of 2 eyes

Causes: Congenital/neurological disorders

Question 2

Amblyopia

Answer 2

• Symptoms: Reduction in visual acuity for one eyes despite no abnormality in actual structure of eyes (so cannot be corrected by spectacles)
• Causes: Defect in one eye early in childhood (e.g. strabismus, eye-patch, astigmatism) results in malformation of ocular dominance columns in V1 associated with that eye)

Question 3

Achromotopsia

Answer 3

• Symptoms: Inability to see any colours except for black, white and shades of grey
• Causes: Lesion in V4

Question 4

Prosopagnosia

Answer 4

• Symptoms: Inability to recognise faces
• Causes: Lesion in infratemporal cortex

Question 5

Akinetopsia

Answer 5

• Symptoms: Inability to see movement
• Causes: Lesion in V5 & V5a

Question 6

Protanopia

Answer 6

• Symptoms: Inability to see light of long wavelengths (i.e., red)
• Causes: Absence of red cone

Question 7

Deuteranopia

Answer 7

• Symptoms: Inability to see light of medium wavelengths
• Causes: Absence of green cones

Question 8

Tritanopia

Answer 8

• Symptoms: Inability to see light of short wavelengths (i.e. blue)
• Causes: Absence of blue cones

Question 9

Protanomaly

Answer 9

• Symptoms: Patients sees ‘less’ red than normal person
• Causes: The red cone has a yellow-shifted absorption spectrum so more red is needed to stimulate it by the same amount as normal red cone

Question 10

Deuteranomaly

Answer 10

• Symptoms: Patients sees ‘less’ green than normal
• Causes: Yellow shifted green cones means that more green is needed to stimulate it by the same amount compared to normal.

Question 11

Conductive hearing loss

Answer 11

• Symptoms:
  1. Failure for sound from environment to reach cochlear transduction mechanism
  2. Decreased air conduction but bone conduction unaffected.
• Causes:
  1. Ear wax in external auditory meatus
  2. Otitis media

Question 12

Sensorineural hearning loss

Answer 12

• Symptoms:
  1. Failure for sound to be transducted/relayed to the cortical hearing centres
  2. Decreased air and bone conduction
• Causes:
  1. Presbycusis
  2. Excessively loud noises
  3. Meniere’s disease

Question 13

Asterognosis

Answer 13

• Symptoms: Inability to judge shape of object based on tactile sensation
• Causes: Lesion in posterior parietal cortex

Question 14

Upper motor neurone disorder

Answer 14

Symptoms:

1. Spastic paralysis
2. Hypertonia
3. Hyper-reflexia (release of primitive reflexes such as suckling reflex and Babinski’s reflex)
4. Clonus

Cause:

• Damage to CNS motor structures (fibres preceeding motor neurones) including:
  1. M1
  2. CST (both brainstem and spinal cord)
  3. Corticobulbar tract

Question 15

Lower motor neurone disorder

Answer 15

Symptoms:

1. Flaccid paralysis
2. Hypotonia
3. Hyporeflexia

Causes:

1. Motor neurone disease (ALS)
2. Guillain-Barré disease
3. Poliomyelitis

Question 16

Parkinson’s disease

Answer 16

Symptoms:

1. Resting tremors
2. Hypertonia
3. Bradykinesia
4. Shuffling gait

Cause: Degeneration of DA neurones in SNpc

Question 17

Huntington’s disease

Answer 17

Symptoms:

1. Chorea (random, jerk-like movements)
2. Chewing/swallowing difficulties
3. Cognitive decline
4. Behavioural changes

Causes: Degeneration of striatal GABAintergic neurones

Question 18

Cerebellar lesion

Answer 18

Symptoms:

1. Dysdiadochokinesia
2. Dysmetria
3. Decomposition of movements
4. Scanning speech

Causes: Lesion of cerebellum

Question 19

Urbach-Weithe syndrome

Answer 19

Symptoms: Emotional disturbances such as absence of fear

Causes: Bilateral calcification of the amygdala and surrounding regions of medial temporal lobe

Question 20

Mesial temporal sclerosis

Answer 20

Symptoms: Intractable temporal lobe epilepsy

Causes: Epileptic focus located in the hippocampus

Question 21

Medial temporal lobe amensia

Answer 21

Symptoms:

1. Severe anterograde amnesia
2. Mild retrograde amnesia

Causes: Damage to medial temporal lobe structures (mainly hippocampus)

Question 22

Korsakoff’s syndrome

Answer 22

Symptoms:

1. Severe anterograde amnesia
2. Mild retrograde amnesia

Causes: Damage to diencephalon as result of thiamine (vitamin B1) deficiency due to chronic alcoholism

Question 23

Meniere’s disease

Answer 23

• Symptoms:
  1. Vertigo
  2. Tinnitus
  3. Hearing loss
  4. Pressure
• Causes: Unknown (could be due to build-up of endolymph)

Question 24

Narcolepsy

Answer 24

Symptoms: Sudden attacks of REM sleep during the day coupled with cataplexy (loss of motor control)

Causes: Mutations in orexin

Question 25

Obsessive compulsive disorder

Answer 25

Symptoms: Obsessive behaviours such as repetitive hand washing and ritualistic daily activities. Causes: Defects in the 5-HT system

Question 26

Broca's aphasia

Answer 26

Symptoms: 1. Patients cannot speak fluently or repeat sentences 2. Patients can comprehend most sentences, but not gramatically complex sentences Causes: Damage to Broca's area (left inferior posterior frontal lobe), deep structures and surrounding areas

Question 27

Wernicke's aphasia

Answer 27

Symptoms: 1. Patients can speak fluently, but speech is nonsensical 2. Patients have problems understanding language Causes: Damage to Wernicke's area (left posterior superior temporal lobe)

Question 28

Conduction aphasia

Answer 28

Symptoms: 1. No deficits in speech comprehension/production 2. Deficit in repeating sentences Causes: Damage to left superior temporal lobe (areas between Broca's and Wernicke's area)

Question 29

Global aphasia

Answer 29

Symptoms: Combination of Broca's, Wernicke's and conduction aphasias Causes: Widespread damage to the left hemisphere

Question 30

Transcortical sensory aphasia

Answer 30

Symptoms: As with Wernicke's aphasia except sentences can be repeated. Causes: Damage to cortex posterior/inferior to Wernicke's area.

Question 31

Transcortical motor aphasia

Answer 31

Symptoms: As with Broca's aphasia, but can repeat sentences. Causes: Damage to cortical regions anterior/superior to Broca's area (e.g. dorsolateral prefrontal cortex, supplementary motor area).

Question 32

Unilateral neglect

Answer 32

Symptoms: Patients are unable to attend to items on one side of the visual field (usually left) Causes: Unilateral parietal lobe (usually right) lesion

Question 33

Unilateral extinction

Answer 33

Symptoms: Patients are able to attend to single items on both sides of visual field but are unable to attend to multiple items presented on both sides (usually neglecting items on affected side when item presented on contralateral side) Causes: Unilateral parietal lobe (usually right) lesion

Question 34

Balint's syndrome

Answer 34

Symptoms: 1. Simultanagnosia: Failure to perceive multiple objects simultaneously 2. Oculomotor apraxia (fixity of gaze): Difficulty diverting overt attention quickly between objects 3. Optic ataxia: Inability to guide hands towards an object using visual cues Causes: Lesions of bilateral parietal lobes