Neurological Disorders

Here is a list of various deficits and syndromes associated with brain damage. Many of these have been discussed in lecture.

Motor deficits

1. Ideational Apraxia

Common Name: Ideational Apraxia
Location of Damage: Lesions in the parietal lobe or frontal lobes.
Key Features: Inability to perform a sequence of motor tasks that involve multiple steps, even though individual movements may be intact. Patients struggle with planning and executing complex actions.

2. Ideomotor Apraxia

Common Name: Ideomotor Apraxia
Location of Damage: Lesions in the left parietal lobe or premotor cortex (often the left hemisphere).
Key Features: Difficulty in executing learned motor movements on command, despite understanding the task. Patients can describe actions but struggle to perform them when asked.

3. Constructional Apraxia

Common Name: Constructional Apraxia
Location of Damage: Damage to the parietal lobes, typically in the right hemisphere.
Key Features: Difficulty with tasks requiring the assembly or construction of objects, such as drawing, building, or organizing objects in space, despite intact motor function.

4. Gait Apraxia

Common Name: Gait Apraxia (also known as Frontal Gait Disorder)
Location of Damage: Lesions in the frontal lobes, particularly in the superior frontal gyrus or white matter tracts (e.g., normal pressure hydrocephalus).
Key Features: Difficulty initiating or coordinating walking, often with a wide-based, shuffling gait.

5. Ataxia

Common Name: Ataxia
Location of Damage: Damage to the cerebellum or its connections, particularly in the cerebellar hemispheres or spinocerebellar tracts.
Key Features: Impaired coordination of voluntary movements, resulting in unsteady gait, lack of balance, and clumsiness in movement (dysmetria).

6. Dysarthria

Common Name: Dysarthria
Location of Damage: Damage to the motor cortex, cerebellum, basal ganglia, or cranial nerves involved in speech (depending on the type of dysarthria).
Key Features: Impaired articulation of speech due to weakness, paralysis, or incoordination of the muscles controlling speech.

7. Hemiplegia

Common Name: Hemiplegia
Location of Damage: Lesions in the motor cortex, internal capsule, or brainstem (often affecting the contralateral side of the body).
Key Features: Paralysis of one side of the body, typically resulting from a stroke or brain injury.

8. Hemiparesis

Common Name: Hemiparesis
Location of Damage: Similar to hemiplegia, caused by damage to the motor cortex or descending motor pathways.
Key Features: Weakness on one side of the body, as opposed to full paralysis, commonly seen after a stroke.

9. Bradykinesia

Common Name: Bradykinesia
Location of Damage: Dysfunction in the basal ganglia, particularly in Parkinson’s disease, affecting the substantia nigra.
Key Features: Slowness of movement, difficulty initiating movement, and overall reduction in spontaneous motor activity.

10. Chorea

Common Name: Chorea
Location of Damage: Lesions or degeneration in the basal ganglia, particularly the caudate nucleus (e.g., in Huntington’s disease).
Key Features: Involuntary, rapid, and irregular movements that are unpredictable and affect various parts of the body.

11. Dystonia

Common Name: Dystonia
Location of Damage: Dysfunction in the basal ganglia, particularly in the globus pallidus or putamen.
Key Features: Sustained or repetitive muscle contractions leading to abnormal postures or twisting movements.

12. Akinetic Mutism

Common Name: Akinetic Mutism
Location of Damage: Lesions in the frontal lobes, particularly the anterior cingulate gyrus or bilateral thalamic lesions.
Key Features: Profound lack of movement (akinesia) and absence of speech (mutism), with patients appearing awake but unresponsive.

13. Myoclonus

Common Name: Myoclonus
Location of Damage: Often associated with dysfunction in the brainstem, cerebral cortex, or spinal cord.
Key Features: Sudden, brief, involuntary muscle jerks that can occur in one or more parts of the body.

14. Agraphia with Apraxia of Hand

Common Name: Agraphia with Apraxia of Hand
Location of Damage: Lesions in the left parietal lobe or the supramarginal gyrus.
Key Features: Inability to write (agraphia) due to motor planning deficits specific to the hand, despite no motor weakness.

15. Alien Hand Syndrome

Common Name: Alien Hand Syndrome
Location of Damage: Lesions in the corpus callosum or frontal lobes.
Key Features: Involuntary and uncontrollable hand movements, where the hand seems to act on its own, often in conflict with the person’s will.

Visual deficits

1. Apperceptive Agnosia

Common Name: Apperceptive Agnosia
Location of Damage: Lesions in the occipital lobes or the ventral stream of the visual pathway (typically bilateral).
Key Features: Impairment in object perception, difficulty with recognizing shapes and integrating visual information, but basic vision (acuity, brightness perception) is intact.

2. Associative Agnosia

Common Name: Associative Agnosia
Location of Damage: Lesions in the occipitotemporal regions of the brain, specifically along the ventral stream.
Key Features: Inability to assign meaning to an object that is perceptually intact. Individuals can copy images but cannot recognize or name objects.

3. Blindsight

Common Name: Blindsight
Location of Damage: Damage to the primary visual cortex (V1) in the occipital lobe, typically bilateral or unilateral.
Key Features: Individuals report no conscious visual perception but can respond to visual stimuli (e.g., motion or location detection) in their blind field.

4. Anton’s Syndrome

Common Name: Anton’s Syndrome (also Cortical Blindness with Denial)
Location of Damage: Bilateral damage to the occipital lobes.
Key Features: Complete cortical blindness accompanied by the denial of blindness (anosognosia), where individuals may believe they can see despite being blind.

5. Akinetopsia

Common Name: Akinetopsia (also Motion Blindness)
Location of Damage: Damage to the middle temporal (MT) / V5 area of the visual cortex.
Key Features: Inability to perceive motion, where objects appear as a series of static images rather than fluid motion.

6. Achromatopsia

Common Name: Achromatopsia (also Cerebral Color Blindness)
Location of Damage: Damage to the V4 area of the visual cortex in the occipital lobe.
Key Features: Complete loss of color vision (monochromatic vision), with individuals perceiving the world in shades of gray, despite normal retinal function.

7. Prosopagnosia

Common Name: Prosopagnosia (also Face Blindness)
Location of Damage: Lesions in the fusiform gyrus, particularly in the right hemisphere (also known as the fusiform face area, FFA).
Key Features: Inability to recognize familiar faces, including one’s own face in extreme cases, despite preserved recognition of objects and other visual stimuli.

8. Topographic Agnosia

Common Name: Topographic Agnosia (also Topographical Disorientation)
Location of Damage: Lesions in the parahippocampal gyrus or right posterior parahippocampal region.
Key Features: Inability to recognize familiar places or landmarks, resulting in difficulty navigating, even in well-known environments.

9. Visual Neglect (Hemispatial Neglect)

Common Name: Visual Neglect or Hemispatial Neglect
Location of Damage: Damage to the right parietal lobe, particularly the inferior parietal lobule.
Key Features: Individuals ignore or fail to attend to the left visual field (contralateral to the lesion), despite preserved basic visual function.

10. Simultanagnosia

Common Name: Simultanagnosia
Location of Damage: Lesions in the parieto-occipital junction, often associated with Balint’s syndrome.
Key Features: Difficulty in perceiving multiple objects simultaneously or integrating visual scenes; individuals can recognize parts of a scene but struggle with the whole picture.

Language deficits

1. Broca’s Aphasia (Non-Fluent Aphasia)

Common Name: Broca’s Aphasia
Location of Damage: Left inferior frontal gyrus, specifically in Broca’s area (Brodmann area 44 and 45), typically in the left hemisphere.
Key Features: Difficulty with speech production, non-fluent speech, but relatively preserved comprehension.

2. Wernicke’s Aphasia (Fluent Aphasia)

Common Name: Wernicke’s Aphasia
Location of Damage: Posterior part of the superior temporal gyrus, typically in the left hemisphere, affecting Wernicke’s area (Brodmann area 22).
Key Features: Fluent but often nonsensical speech with poor comprehension and difficulty understanding language.

3. Global Aphasia

Common Name: Global Aphasia
Location of Damage: Extensive damage to the left perisylvian cortex, affecting both Broca’s and Wernicke’s areas and other regions in between.
Key Features: Severe impairment in both language production and comprehension, with limited verbal output.

4. Conduction Aphasia

Common Name: Conduction Aphasia
Location of Damage: Arcuate fasciculus, the white matter tract connecting Broca’s and Wernicke’s areas.
Key Features: Fluent speech with good comprehension but poor repetition and frequent phonemic paraphasias.

5. Anomic Aphasia

Common Name: Anomia or Anomic Aphasia
Location of Damage: Typically damage to the left temporal lobe or parietal lobe, but it can involve a variety of cortical regions.
Key Features: Difficulty in naming objects (word-finding problems), while fluency, comprehension, and repetition are largely preserved.

6. Transcortical Motor Aphasia

Common Name: Transcortical Motor Aphasia
Location of Damage: Damage to the anterior superior frontal lobe near Broca’s area but not directly affecting it, often due to ischemia.
Key Features: Similar to Broca’s aphasia, with non-fluent speech, but with intact repetition ability.

7. Transcortical Sensory Aphasia

Common Name: Transcortical Sensory Aphasia
Location of Damage: Posterior parietal or temporo-occipital region (near but sparing Wernicke’s area).
Key Features: Fluent speech with impaired comprehension and poor ability to name objects, but preserved repetition.

8. Alexia without Agraphia (Pure Alexia)

Common Name: Alexia without Agraphia (or Pure Alexia)
Location of Damage: Lesion in the left occipital lobe and the splenium of the corpus callosum, disconnecting visual information from language areas.
Key Features: Impairment in reading (alexia) without difficulties in writing (agraphia).

9. Mixed Transcortical Aphasia

Common Name: Mixed Transcortical Aphasia
Location of Damage: Isolated language areas due to damage in the watershed areas around the perisylvian cortex, sparing both Broca’s and Wernicke’s areas.
Key Features: Impaired language production and comprehension, but with preserved repetition.

10. Disconnection Syndromes (Disconnexion Aphasia)

Common Name: Disconnection Aphasia
Location of Damage: Disruption in connections between critical brain regions, typically involving white matter tracts such as the arcuate fasciculus or corpus callosum.
Key Features: Variability in symptoms, often including difficulties with repetition, naming, or integrating sensory information across modalities.

Somatic disorders

1. Tactile Agnosia

Common Name: Tactile Agnosia (also Astereognosis)
Location of Damage: Lesions in the parietal lobe, particularly the somatosensory cortex or posterior parietal cortex.
Key Features: Inability to recognize objects by touch, despite having intact sensory and motor function. Patients can feel the object but cannot identify it based on texture, size, or shape.

2. Agraphesthesia

Common Name: Agraphesthesia
Location of Damage: Damage to the parietal lobe, particularly the postcentral gyrus.
Key Features: Inability to recognize letters or numbers traced on the skin, despite intact sensation and motor function.

3. Hemisensory Loss

Common Name: Hemisensory Loss
Location of Damage: Lesions in the thalamus, somatosensory cortex, or spinothalamic tracts.
Key Features: Loss or reduction of sensation (pain, temperature, touch) on one side of the body, typically contralateral to the brain lesion.

4. Phantom Limb Syndrome

Common Name: Phantom Limb Syndrome
Location of Damage: Associated with amputation or damage to the primary somatosensory cortex or peripheral nerves.
Key Features: Perception of sensations, including pain, in a limb that has been amputated. Patients often feel as though the missing limb is still present.

5. Allodynia

Common Name: Allodynia
Location of Damage: Dysfunction in sensory pathways (can occur at the level of peripheral nerves, spinal cord, or brain), often linked to chronic pain conditions.
Key Features: Painful sensation triggered by stimuli that are normally non-painful (e.g., light touch).

6. Hyperalgesia

Common Name: Hyperalgesia
Location of Damage: Can result from injury or dysfunction in peripheral nerves, spinal cord, or central pain pathways.
Key Features: Heightened sensitivity to painful stimuli, where a normally painful stimulus is experienced as more intense.

7. Anosognosia for Hemiplegia

Common Name: Anosognosia for Hemiplegia
Location of Damage: Typically results from lesions in the right parietal lobe or right frontal lobe.
Key Features: Lack of awareness of paralysis or sensory deficits on one side of the body. Patients are often unaware that they cannot move or feel part of their body.

8. Paresthesia

Common Name: Paresthesia
Location of Damage: May arise from damage to the peripheral nerves, spinal cord, or somatosensory cortex.
Key Features: Abnormal sensations such as tingling, “pins and needles,” or burning, often without an obvious external cause.

9. Neglect Syndrome (Hemispatial Neglect)

Common Name: Neglect Syndrome (also Hemispatial Neglect)
Location of Damage: Lesions in the right parietal lobe, specifically affecting the posterior parietal cortex.
Key Features: Failure to attend to or respond to sensory stimuli (visual, auditory, or tactile) on the left side of space, despite intact sensory pathways.

10. Deafferentation

Common Name: Deafferentation
Location of Damage: Damage or loss of peripheral nerve input to the central nervous system.
Key Features: Loss of sensory input from a specific part of the body, resulting in a lack of sensory feedback and, sometimes, motor dysfunction.

11. Thalamic Pain Syndrome (Dejerine-Roussy Syndrome)

Common Name: Thalamic Pain Syndrome
Location of Damage: Damage to the thalamus, usually following a thalamic stroke.
Key Features: Chronic, severe pain on the contralateral side of the body, often accompanied by sensory loss and dysesthesia (unpleasant abnormal sensations).

12. Dyspraxia

Common Name: Dyspraxia (also known as Developmental Coordination Disorder)
Location of Damage: Thought to involve dysfunction in the parietal lobes or frontal motor areas.
Key Features: Difficulty with motor coordination that affects tasks like buttoning clothes or using tools, despite normal sensory function and intelligence.

13. Tactile Extinction

Common Name: Tactile Extinction
Location of Damage: Lesions in the right parietal lobe, especially in the posterior parietal cortex.
Key Features: Inability to perceive stimuli on one side of the body when bilateral stimulation is applied (e.g., touching both hands at the same time), despite normal sensation when each side is stimulated alone.

Illusions and Delusions

1. Capgras Syndrome

Common Name: Capgras Syndrome (also known as the Capgras Delusion)
Location of Damage: Often associated with lesions or dysfunction in the right frontal lobe or right temporal lobe, and disconnection between visual and limbic areas.
Key Features: Delusional belief that a person, usually a close relative or friend, has been replaced by an imposter. The emotional connection to the person is lost, leading to the perception that they are no longer the same individual.

2. Somatoparaphrenia

Common Name: Somatoparaphrenia
Location of Damage: Typically results from damage to the right parietal lobe or right frontal lobe, often after a stroke affecting the right hemisphere.
Key Features: Delusion in which patients deny ownership of a limb or an entire side of the body, often insisting that it belongs to someone else, despite having normal sensation and motor function.

3. Fregoli Delusion

Common Name: Fregoli Delusion
Location of Damage: Associated with dysfunction in the right hemisphere, particularly the temporal and frontal lobes.
Key Features: Delusional belief that different people are, in fact, a single person who changes appearance or is in disguise. Often involves paranoia and misidentification of others.

4. Reduplicative Paramnesia

Common Name: Reduplicative Paramnesia
Location of Damage: Lesions typically in the right hemisphere, involving the frontal lobes and the parietal lobes, as well as the limbic system.
Key Features: Delusion in which the individual believes that a place, usually a familiar location, has been duplicated or exists in two locations at once, or that it has been relocated to another place.

5. Cotard Delusion

Common Name: Cotard Delusion (also known as Walking Corpse Syndrome)
Location of Damage: Associated with dysfunction in the parietal lobe or prefrontal cortex, as well as regions associated with emotional processing.
Key Features: Delusional belief that the individual is dead, does not exist, or has lost their internal organs. Patients may deny the existence of parts of their body or the world around them.

6. Charles Bonnet Syndrome

Common Name: Charles Bonnet Syndrome
Location of Damage: Related to visual pathway dysfunction, often occurring in individuals with vision loss (e.g., macular degeneration or cataracts).
Key Features: Visual hallucinations in otherwise cognitively intact individuals. Hallucinations are often complex (e.g., faces, animals, objects) and are recognized by the patient as not real.

7. Erotomania

Common Name: Erotomania
Location of Damage: Dysfunction or lesions in the frontal lobes or limbic system, though the specific neuroanatomy is unclear.
Key Features: Delusional belief that another person, typically someone of higher social status (e.g., a celebrity), is in love with the patient, despite clear evidence to the contrary.

8. Delusional Misidentification Syndrome (General)

Common Name: Delusional Misidentification Syndrome
Location of Damage: Lesions in the right hemisphere, particularly affecting the frontal lobes and temporal lobes, as well as ventral visual processing areas.
Key Features: General term for disorders involving the misidentification of people, places, or objects. This includes Capgras Syndrome, Fregoli Delusion, and Reduplicative Paramnesia.

9. Phantom Boarder Syndrome

Common Name: Phantom Boarder Syndrome
Location of Damage: Linked to dysfunction in the frontal lobes, but the specific neuroanatomy is not well understood.
Key Features: Delusion in which the patient believes that unseen individuals are living in their home. This is often associated with paranoia and hallucinations.

10. Somatic Delusions

Common Name: Somatic Delusions
Location of Damage: Associated with dysfunction in the right hemisphere, particularly the frontal lobes and parietal lobes.
Key Features: Delusional beliefs involving false perceptions about the body. This can include beliefs that one’s body is infested with parasites, that a body part is deformed, or that an internal organ is damaged.

11. Illusory Palpation

Common Name: Illusory Palpation
Location of Damage: Often linked to damage or dysfunction in somatosensory areas of the parietal lobe.
Key Features: Sensory illusions where patients feel phantom sensations such as touching or pressure that does not correspond to any actual external stimuli.

12. Visual Illusions

Common Name: Visual Illusions
Location of Damage: Damage to the occipital lobe or visual processing pathways, particularly in the ventral stream.
Key Features: Distorted or misperceived visual stimuli where real objects are seen in a warped or altered way (e.g., objects appearing larger, smaller, or distorted in shape).

13. Anosognosia

Common Name: Anosognosia
Location of Damage: Typically associated with damage to the right parietal lobe, especially in cases of hemiplegia or sensory loss.
Key Features: Lack of awareness or denial of a significant deficit, such as paralysis or blindness. The patient is unaware of the condition despite clear evidence.

14. Autoscopic Hallucinations

Common Name: Autoscopic Hallucinations
Location of Damage: Dysfunction in the temporo-parietal junction, particularly the right hemisphere.
Key Features: A hallucination where the individual perceives a visual double of themselves (out-of-body experience) often occurring in space outside the body.