Hemispheric localization signs
Frontal lesions:
Unilateral frontal disease:
1. motor abnormalities (except if entirely prefrontal): contralateral spastic hemiplegia
2. impairment of cognitive functions: inattentiveness, lack of concentration and capacity of sustained mental activity, and inability to maintain serial relationships of events and to shift from one mental activity to another = impersistence in all assigned tasks and perseveration
4. frontal release (disinhibition) signs (sucking, grasping, groping reflexes) = utilization behaviors, paratonic rigidity (gegenhalten)
5. akinesia and lack of initiative and spontaneity (apathy, anhedonia and abulia or the extreme akinetic mutism), loss of drive, impairment of consecutive planning,
Dominant-side frontal disease:
1. motor abnormalities (except if entirely prefrontal): contralateral spastic hemiplegia
2. speech and language disorder (dominant hemisphere): laconic speech, lack of spontaneity of speech, telegraphic speech (agrammatism), loss of fluency, perseveration, tendecy to whisper and dysarthria. Agraphia, lip apraxia.
4. frontal release (disinhibition) signs (sucking, grasping, groping reflexes) = utilization behaviors, paratonic rigidity (gegenhalten)
5. akinesia and lack of initiative and spontaneity (apathy, anhedonia and abulia or the extreme akinetic mutism), loss of drive, impairment of consecutive planning,
Bifrontal disease:
1. bilateral hemiplegia
2. spastic bulbar palsy
3. akinesia and lack of initiative and spontaneity (apathy, anhedonia and abulia or the extreme akinetic mutism), loss of drive, impairment of consecutive planning,
6. incontinence
7. frontal release (disinhibition) signs (sucking, grasping, groping reflexes) = utilization behaviors, paratonic rigidity (gegenhalten)
Evaluation tests: card sorting test, proverb interpretation, sequencing of pictures and three-step posture test. The latter is a famous bedside test: slap palm, followed by hitting with fist then strike with back of hand. Patients with frontal disorders do it in incorrect sequence, often perseverate, or make unwanted gestures,…
Temporal lesions
Dominant lobe:
1. homonymous upper quadranopia
2. Wernicke aphasia or auditory verbal agnosia (word deafness)
3. amusia or agnosia for sounds
4. dysnomia or amnesic aphasia (defect in retrieval of words)
5. visual agnosia
6. (Korsakoff syndrome)
Non-dominant lobe:
1. homonymous upper quadranopia
2. inability to judge spatial relationship
3. amusia or agnosia for sounds
4. delirium
Either lobe:
1. auditory, visual, olfactory, and gustatory hallucinations
2. dreamy state with uncinate seizures
3. disturbance in time perception
Bilateral disease:
1. Korsakoff syndrome
2. apathy and placidity
3. hypermetamorphopsia, hyperorality, hypersexuality, blunted emotional reactivity (Klüver-Buçy syndrome)(seldom full syndrome in man).
Parietal lesions
Dominant lobe:
1. corticosensory syndrome (astereognosia, sensory discrimination (inability to localize a stimuli), two-point discrimination)(or total hemianesthesia in white matter lesions) and sensory extinction
2. mild hemiparesis
3. homonymous hemianopia or inferior quadranopia or visual inattention or ansosognosia, hemineglect
4. abolition of OKN with target moving toward side of the lesion
5. alexia
6. Gerstmann syndrome (acalculia, left/right confusion of body parts (asomatognosia), dysgraphia, digital agnosia)[angular gyrus]
7. tactile agnosia (bimanual astereognosia).
8. bilateral ideomotor apraxia, or the inability to execute learned motor skills on command or by imitation. In the parietal variety, the ability to comprehend gestures as well as to pantomime to verbal command is lost (light a match or…); whereas in the frontal variety, gesture comprehension is normal.
Ideational apraxia is when the entire concept of an action is lost and the subject can not even attempt it. This can be tested by having subjects perform sequential tasks like having them turn on a flashlight after given two batteries and an empty flashlight.
Non-dominant lobe:
1. corticosensory syndrome (astereognosia, sensory discrimination (inability to localize a stimuli, two-point discrimination or total hemianesthesia in white matter lesions) and sensory extinction
2. mild hemiparesis
4. anosognosia (indifference, ignorance, or unawareness of paralysis, or estrange the affected side), bodyhemineglect, visual and tactile hallucinations of anosognostic side [superior parietal lobe]
5. abolition of OKN with target moving toward side of the lesion
6. visuospatial disorders (spatial neglect: naming objects in room or draw a clock)
7. topographic memory loss
9. constructional apraxia (copy complex figure, draw clock)
10. confusion
11. tendency to keep the eyes closed, resist opening, and blepharospasm
Bilateral disease:
1. visual spatial imperception, spatial disorientation, and Balint syndrome
Occipital lesions
Dominant lobe:
1. homonymous hemianopia/ hemiachromatopia
2. alexia, color-naming defect (if deep white matter or splenium)
3. elementary hallucinations
4. visual object agnosia (recognition by palpation, smell, etc. but failure to name and indicate the use of a seen object) usually associated with alexia and prosopagnosia
Non-dominant lobe:
1. homonymous hemianopia
2. visual illusions (metamorphopsia: distortion in form, size, color etc.), palinopsia (perseveration of visual images) and (hallucinations)
3. loss of topographic memory and visual orientation [medial temporo-occipital area]
Bilateral disease:
1. Balint syndrome (inability to project gaze in visual field (optic ataxia), failure to precisely grasp under visual guidance and visual inattention mainly to the peripheral visual fields
2. cortical blindness (loss of threat reflex with preserved pupillary light reflexes and absent OKN, alpha pattern is lost on EEG, no cortical responses to VEP)
3. Anton syndrome (denial of cortical blindness)
4. prosopagnosia, simultanagnosia [ventromesial occipitotemporal regions]
5. loss of perception of color
Buccofacial apraxia, or apraxia of activities of the mouth and face, can be tested by having the patients perform such actions as blowing out a match and licking crumbs off their lips.