Disorders Flashcards
Strabismus
- Symptoms:
Misalignment of 2 eyes
Causes: Congenital/neurological disorders
Amblyopia
- 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)
Achromotopsia
- Symptoms: Inability to see any colours except for black, white and shades of grey
- Causes: Lesion in V4
Prosopagnosia
- Symptoms: Inability to recognise faces
- Causes: Lesion in infratemporal cortex
Akinetopsia
- Symptoms: Inability to see movement
- Causes: Lesion in V5 & V5a
Protanopia
- Symptoms: Inability to see light of long wavelengths (i.e., red)
- Causes: Absence of red cone
Deuteranopia
- Symptoms: Inability to see light of medium wavelengths
- Causes: Absence of green cones
Tritanopia
- Symptoms: Inability to see light of short wavelengths (i.e. blue)
- Causes: Absence of blue cones
Protanomaly
- 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
Deuteranomaly
- 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.
Conductive hearing loss
- 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
Sensorineural hearning loss
- 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
Asterognosis
- Symptoms: Inability to judge shape of object based on tactile sensation
- Causes: Lesion in posterior parietal cortex
Upper motor neurone disorder
Symptoms:
- Spastic paralysis
- Hypertonia
- Hyper-reflexia (release of primitive reflexes such as suckling reflex and Babinski’s reflex)
- Clonus
Cause:
- Damage to CNS motor structures (fibres preceeding motor neurones) including:
1. M1
2. CST (both brainstem and spinal cord)
3. Corticobulbar tract
Lower motor neurone disorder
Symptoms:
- Flaccid paralysis
- Hypotonia
- Hyporeflexia
Causes:
- Motor neurone disease (ALS)
- Guillain-Barré disease
- Poliomyelitis
Parkinson’s disease
Symptoms:
- Resting tremors
- Hypertonia
- Bradykinesia
- Shuffling gait
Cause: Degeneration of DA neurones in SNpc
Huntington’s disease
Symptoms:
- Chorea (random, jerk-like movements)
- Chewing/swallowing difficulties
- Cognitive decline
- Behavioural changes
Causes: Degeneration of striatal GABAintergic neurones
Cerebellar lesion
Symptoms:
- Dysdiadochokinesia
- Dysmetria
- Decomposition of movements
- Scanning speech
Causes: Lesion of cerebellum
Urbach-Weithe syndrome
Symptoms: Emotional disturbances such as absence of fear
Causes: Bilateral calcification of the amygdala and surrounding regions of medial temporal lobe
Mesial temporal sclerosis
Symptoms: Intractable temporal lobe epilepsy
Causes: Epileptic focus located in the hippocampus
Medial temporal lobe amensia
Symptoms:
- Severe anterograde amnesia
- Mild retrograde amnesia
Causes: Damage to medial temporal lobe structures (mainly hippocampus)
Korsakoff’s syndrome
Symptoms:
- Severe anterograde amnesia
- Mild retrograde amnesia
Causes: Damage to diencephalon as result of thiamine (vitamin B1) deficiency due to chronic alcoholism
Meniere’s disease
- Symptoms:
1. Vertigo
2. Tinnitus
3. Hearing loss
4. Pressure - Causes: Unknown (could be due to build-up of endolymph)
Narcolepsy
Symptoms: Sudden attacks of REM sleep during the day coupled with cataplexy (loss of motor control)
Causes: Mutations in orexin
Obsessive compulsive disorder
Symptoms: Obsessive behaviours such as repetitive hand washing and ritualistic daily activities.
Causes: Defects in the 5-HT system
Broca’s aphasia
Symptoms:
- Patients cannot speak fluently or repeat sentences
- 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
Wernicke’s aphasia
Symptoms:
- Patients can speak fluently, but speech is nonsensical
- Patients have problems understanding language
Causes: Damage to Wernicke’s area (left posterior superior temporal lobe)
Conduction aphasia
Symptoms:
- No deficits in speech comprehension/production
- Deficit in repeating sentences
Causes: Damage to left superior temporal lobe (areas between Broca’s and Wernicke’s area)
Global aphasia
Symptoms: Combination of Broca’s, Wernicke’s and conduction aphasias
Causes: Widespread damage to the left hemisphere
Transcortical sensory aphasia
Symptoms: As with Wernicke’s aphasia except sentences can be repeated.
Causes: Damage to cortex posterior/inferior to Wernicke’s area.
Transcortical motor aphasia
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).
Unilateral neglect
Symptoms: Patients are unable to attend to items on one side of the visual field (usually left)
Causes: Unilateral parietal lobe (usually right) lesion
Unilateral extinction
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
Balint’s syndrome
Symptoms:
- Simultanagnosia: Failure to perceive multiple objects simultaneously
- Oculomotor apraxia (fixity of gaze): Difficulty diverting overt attention quickly between objects
- Optic ataxia: Inability to guide hands towards an object using visual cues
Causes: Lesions of bilateral parietal lobes
