Neurological Examination, clinical cases and neuropsychological ...

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23/07/54 Gerstmann syndrome is a neurological disorder that is characterized by a constellation of symptoms that suggests the presence of a lesion in a particular area of the brain. Gerstmann syndrome is characterized by four primary symptoms: ►Dysgraphia/agraphia: deficiency in the ability to write ► Dyscalculia/acalculia: difficulty in learning or comprehending mathematics ► Finger agnosia: inability to distinguish the fingers on the hand ► Left‐right disorientation Causes This disorder is often associated with brain lesions in the dominant (usually left) hemisphere including the angular and supramarginal gyri near the temporal and parietal lobe junction. There is significant debate in the scientific literature as to whether Gerstmann Syndrome truly represents a unified, theoretically motivated syndrome. Thus its diagnostic utility has been questioned by neurologists and neuropsychologists alike. The angular gyrus is generally involved in translating visual patterns of letter and words into meaningful information, such as is done while reading. In adults In adults, the syndrome may occur after a stroke or in association with damage to the parietal lobe. In addition to exhibiting the above symptoms, many adults also experience aphasia, which is a difficulty in expressing oneself when speaking, in understanding speech, or in reading and writing. In children There are few reports of the syndrome, sometimes called Developmental Gerstmann syndrome, in children. The cause is not known. Most cases are identified when children reach school age, a time when they are challenged with writing and math exercises. Generally, children with the disorder exhibit poor handwriting and spelling skills, and difficulty with math functions, including adding, subtracting, ti multiplying, l i and dividing. idi An inability to differentiate right from left and to discriminate among individual fingers may also be apparent. In addition to the four primary symptoms, many children also suffer from constructional apraxia, an inability to copy simple drawings. Frequently, there is also an impairment in reading. Children with a high level of intellectual functioning as well as those with brain damage may be affected with the disorder. Bálint's syndrome is an uncommon and incompletely understood triad of severe neuropsychological impairments involving space representation (visuospatial processing). Its three major components are 1) Simultanagnosia, i.e., the inability to perceive the visual field as a whole, 2) Ocular apraxia, a deficit of visual scanning, and Apraxia—inability to carry out familiar movements when asked to do so 3) Optic ataxia, an impairment of pointing and reaching under visual guidance. The syndrome was named in 1909 for the Austro‐Hungarian neurologist Rezső Bálint who had been the first to identify it. Since it represents impairment of both visual and language functions, it is a significant disability that can affect the patient's safety even in one's own home environment, and can render the person incapable of maintaining employment. Lack of awareness of this syndrome may lead to a misdiagnosis and resulting inappropriate or inadequate treatment. Therefore, clinicians should be familiar with Bálint's syndrome and its various etiologies. Balint's syndrome occurs most often with an acute onset as a consequence of multiple bilateral strokes. The most frequent cause of complete Balint's syndrome is said by some to be sudden and severe hypotension, resulting in bilateral borderzone infarction in the occipito‐parietal region. More rarely, cases of progressive Balint's syndrome have been found in degenerative disorders such as Alzheimer's disease or certain other traumatic brain injuries at the border of the parietal and the occipital lobes of the brain. Acalculia 7/23/2011 NEUROPSYCHIATRY 226 Body Schema Disturbance 415703 Cognitive Neuropsychology Week 6: The Temporal lobes 7/23/2011 NEUROPSYCHIATRY 227 Naiphinich Kotchabhakdi, Ph.D. Naiphinich Kotchabhakdi, Ph.D. Director, Salaya Stem Cell R & D Project, Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University Salaya Campus, 999 Phutthamonthol 4 Road, Salaya, Phutthamonthol, Nakornpathom 73170 Thailand Email: scnkc@mahidol.ac.th or naiphinich@gmail.com Web: www.neuroscience.mahidol.ac.th 38
23/07/54 Main Objectives: 1. The temporal lobes and their functions 2. The Auditory System 3. Auditory Perception and Auditory Cortical Organization 4. The two Stream Hypothesis: The Dorsal stream, “Where or How” and The Ventral Stream, “What” 5. Deep brain structures in Temporal lobe, e.g., Limbic brain structures and their functions 6. Neuropsychology of the Temporal lobes. The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in auditory perception and is home to the primary auditory cortex. It is also important for the processing of semantics in both speech and vision. The temporal lobe contains the hippocampus and plays a key role in the formation of long‐term memory. The superior temporal gyrus includes an area (within the Sylvian fissure) where auditory signals from the cochlea (relayed via several subcortical nuclei) first reach the cerebral cortex. This part of the cortex (primary auditory cortex) is involved in hearing. Adjacent areas in the superior, posterior and lateral parts of the temporal lobes are involved in high‐level auditory processing. In humans this includes speech, for which the left temporal lobe in particular seems to be specialized. Wernicke's area, which spans the region between temporal and parietal lobes, plays a key role (in tandem with Broca's area, which is in the frontal lobe). The functions of the left temporal lobe are not limited to low‐level perception but extend to comprehension, naming, verbal memory and other language functions. The underside (ventral) part of the temporal cortices appear to be involved in high‐level visual processing of complex stimuli such as faces (fusiform gyrus) and scenes (parahippocampal gyrus). Anterior parts of this ventral stream for visual processing are involved in object perception and recognition. The medial temporal lobes (near the Sagittal plane that divides left and right cerebral hemispheres) are thought to be involved in episodic/declarative memory. Deep inside the medial temporal lobes lie the hippocampi, which are essential for memory function ‐ particularly the transference from short to long term memory and control of spatial memory and behavior. Damage to this area typically results in anterograde amnesia. The superior temporal gyrus is one of three (sometimes two) gyri in the temporal lobe of the human brain, which is located laterally to the head, situated somewhat above the external ear. The superior temporal gyrus is bounded by: the lateral sulcus above; the superior temporal sulcus below; an imaginary line drawn from the preoccipital notch to the lateral sulcus posteriorly. The superior temporal gyrus contains several important structures of the brain, including: Brodmann areas 41 and 42, marking the location of the primary auditory cortex, the cortical region responsible for the sensation of sound Wernicke's area, Brodmann 22p, an important region for the processing of speech so that it can be understood as language. Brain mechanisms for auditory functions (Hearing) 7/23/2011 NEUROPSYCHIATRY 232 Auditory Perception or Hearing (or audition; "auditory" or "aural") is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses. The inability to hear is called deafness. In humans and other vertebrates, hearing is performed primarily by the auditory system: vibrations are detected by the ear and transduced into nerve impulses that are perceived by the brain (primarily in the temporal lobe). Like touch, audition requires sensitivity to the movement of molecules in the world outside the organism. Both hearing and touch are types of mechanosensation. The primary auditory cortex cortex is the region of the brain that is responsible for the processing of auditory (sound) information. Corresponding roughly with Brodmann areas 41 and 42, it is located on the temporal lobe, and performs the basics of hearing—pitch and volume. Besides receiving input from the ear and lower centers of the brain, the primary auditory cortex also transmits signals back to these areas. 39
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