Sensory Examination
J. Terrence Jose Jerome in Clinical Examination of the Hand, 2022
Cortical sensory functions: Interpretative sensory functions that require analysis of individual sensory modalities by the parietal lobes to provide discrimination. Individual sensory modalities must be intact to measure cortical sensation.Stereognosis: Ability to recognize and identify objects by feeling them. The absence of this ability is termed astereognosis.Graphesthesia: Ability to recognize symbols written on the skin. The absence of this ability is termed graphanesthesia.Two-point discrimination: Ability to recognize simultaneous stimulation by two blunt points. It is measured by the distance between the points required for recognition.Touch localization(topognosis): Ability to localize stimuli to parts of the body. Topagnosia is the absence of this ability.Double simultaneous stimulation: Ability to perceive a sensory stimulus when corresponding areas on the opposite side of the body are stimulated simultaneously. Loss of this ability is termed sensory extinction.
Discussions (D)
Terence R. Anthoney in Neuroanatomy and the Neurologic Exam, 2017
Presumably, authors define astereognosis in this manner—i.e., requiring that the simple sensory modalities be largely intact—so as to make it indicative of damage above the thalamus, either cortical or subcortical. Consequently, it is striking that these same authors usually do not define deficiencies in other cortical sensations the same way, but instead allow them to coexist with marked deficiencies in simple sensory modalities, caused by lesions at the thalamic level or below. As examples, Adams and Victor (1985) describe impairment of “discriminative (‘cortical’) sensory functions such as two-point discrimination, figure writing [= graphesthesia, p. 122], and the ability to detect the direction and speed of a moving stimulus on the skin” in lesions of the posterior columns (p. 126); DeJong notes that “The ability to identify letters written on the skin [= graphesthesia] is interfered with in peripheral nerve and spinal cord lesions” (1979, p. 74);1 Chusid describes loss of “2-point discrimination sense” in hemisection of the spinal cord (1985, p. 229); and Ross describes loss of two-point discrimination in lesions of “peripheral nerves” and of “the posterior columns of the spinal cord” (1985, p. 242).
Impairment of functions of the nervous system
Ramar Sabapathi Vinayagam in Integrated Evaluation of Disability, 2019
Cortical sensation consists of stereognosis, “Two-Point” discrimination, and graphesthesia. Stereognosis refers to the ability of a person to recognize known objects, such as a coin, key, or pen, with their eyes closed. Astereognosis indicates the inability of a person to recognize objects by touch sensation with the eyes closed. “Two-Point” discrimination represents the ability to perceive the double stimuli applied simultaneously by a pair of calipers with blunt ends. If the person is unable to discriminate and recognize two points, they are deemed to have an impairment of “Two-Point” discrimination. In graphesthesia, a person can recognize either the alphabet or numbers written on their skin by the perception of touch (Tables 6.36 through 6.38).
Posterior cortical atrophy: clinical, neuroimaging, and neuropathological features
Published in Expert Review of Neurotherapeutics, 2023
John Best, Marianne Chapleau, Gil D. Rabinovici
The neurologic exam in individuals with PCA frequently demonstrates dyspraxia or apraxia. Upon initial observation, patients may have trouble orienting themselves properly in the exam room, sometimes bumping into objects. They may have difficulty seeing the examiner and maintaining adequate eye contact due to loss of visual fixation. The examiner should assess a patient’s ability to perform movements under visual guidance, locate objects in the room, copy hand positions, draw and copy geometric figures, and read and write. A careful exam can uncover subtle visual field deficits or extinction to simultaneous bilateral visual stimuli. Gait is hesitant in the context of poor vision. There may be evidence of Balint’s syndrome, specifically oculomotor apraxia (inability to intentionally move eyes toward an object) or optic ataxia (difficulty reaching for an object they are looking at). The motor exam is variable and can sometimes show evidence of parkinsonism, myoclonus, or tremor. Sensory exam shows normal primary sensory function but can show evidence of impaired cortical sensory function, such as inability to identify an object by touch (astereognosis) or inability to perceive written numbers or letters on their skin (agraphesthesia). The gait exam is typically normal; however, evidence of a parkinsonian gait could suggest co-morbid or primary Lewy body pathology.
Related Knowledge Centers
- Sense
- Visual Perception
- Parietal Lobe
- Dorsal Column–Medial Lemniscus Pathway
- Cerebral Cortex
- Functional Magnetic Resonance Imaging
- Alzheimer's Disease
- Stereognosis
- Memory
- Somatosensory System