STUDY - Technical - New Dacian's Medicine
Paresthesia
and other sensory disorders
(2)
Translation Draft
I will continue yesterday's post with little clarification on the primary sensitivity.
I will continue yesterday's post with little clarification on the primary sensitivity.
The
painful sense is usually tested with a sharp tip, asking the
patient to focus on the unpleasant sting or quality of the
stimulus and not just on the sensations of pressure or tactile
felt.
Areas of hypoalgesia should be marked from the areas least sensitive to pain, to those that perceive pain almost normally. Thermal sensitivity, both cold and hot, is probably best appreciated by touching the skin for a few seconds with a container full of water at the desired temperature (thermometrically checked). It is gratifying if the patient perceives as warm the container located at 35-36 degrees celsius and as cold the one at 28-32 degrees celsius. Between 28 and 32 degrees celsius most people can distinguish thermal differences of 1 degree celsius, progressively.
Because hot and cold sensitivity is served by different receptors, both types of sensitivity should be tested. The tactile sensitivity is usually tested using a piece of cotton wool or a fine brush of camel hair.
In general, it is good to avoid testing the tactile sensitivity in the hairy skin, due to the depth at which the sensory endings surrounding each hair follicle are located. The patient, who will have his eyes closed, must confirm whenever he feels the tactile stimulus. It can also indicate where he felt the stimulus, although this test also involves a sense of localization.
Proprioception, one of the most important functions of the sensory system, is investigated by testing the perception of the position of the joints. This is usually done first at the level of the halo and then at the level of the fingers. The patient closes his eyes and completely relaxes the examined region.
In the case of the halo, some begin with the neutral position of the haluces and by gently the haluces of the patient between the font and the forefinger, on either side of the halo (not above or below). Haluces is moved a few degrees in both dorsal and plantar direction, the patient must specify whether the movement was up or down.
We need to make sure the patient understands that the direction of the halos is being tested at the time of stopping. A patient who lacks a sense of position at the level of the tested part will have an error rate of 50%, as there are two choices. Responses that are significantly greater than 50% in error should be interpreted with caution.
If errors occur when recognizing the direction of passive movements of the halucus, then other phalanx joints, fist and elbow joints will be tested. Testing of the sense of joint positioning, mainly at the shoulder level, can be carried out by asking the patient to join the two index fingers when the arms are extended and the eyes closed. Normal people can perform this gesture accurately, the error being up to one centimeter.
The vibrating sense is tested with a diapazon, preferably a large one, which vibrates at 128 Hz. The decrease in the amplitude of the vibration of this type of diapazon is slow enough to be useful in quantitative testing, considering that it takes 15 to 20 seconds to decrease to a level below the perceptible threshold.
Vibratory sensitivity is usually investigated at the level of bone protrusions, specifically in the maleolar area of the ankles, rotulian, anterior iliac spine, spiny apophyses of the vertebral bodies, metacarpo-phalangeal joints (finger joints of the hands), ulnar stiloid apophysis, elbow and acromion.
The places of preference in assessing vibrating sensitivity are the forehead and sternum. The examiner can compare the threshold of perception in a particular area of the patient with that which he perceives himself. A rough approximation of the degree of loss of vibrating sense can be obtained by counting the seconds in which the examiner senses vibrations while the patient does not. The patient must be clear that it is necessary to direct his attention to the vibrations produced and not only to the pressure exerted by the root of the diapazon.
Let's continue with the cortical sensibility. The cortical segment of sensitivity is usually tested by assessing discrimination between two points, the localization of tactile stimulus, stereognosia, graphesthesia and simultaneous bilateral stimulation. The modification of these sensory tests, associated with an unchanged primary sensitivity in a conscious and cooperative patient, signifies a lesion of the parietal cortex or of the talamocortical projections to the parietal lobe.
If primary sensitivity is affected, it is not possible to investigate these discriminatory cortical functions. Discrimination between two points shall be tested using a special compass whose tips can be positioned from 2 mm to a few centimeters away and then applied simultaneously to the area to be tested.
Frequently, the test is carried out at the pulp of the fingers (a normal person may perceive the tips of the compass separately, when they are about 3 mm apart). The tongue and lips may perceive two separate points less than 3 mm away, but other regions of the body may have thresholds of discrimination, between two points, of a few centimeters. Symmetrical areas of the body will always be compared, as the deficiency from a specific parietal lesion is homolateral. This applies to all investigations of the cortical sensitivity segment.
The localization of tactile sensations is done by requiring the patient to close his eyes and the examiner exerts a slight pressure with his fingertips in an area that the person examined must specify. It is customary for the patient to indicate with the tip of his finger the place that the doctor touched.
Simultaneous bilateral stimulation of the homologous areas (e.g. the dorsal part of the hands) is performed to determine whether tactile perception is considerably reduced in one part of the body compared to the other. The phenomenon is known as extinction at simultaneous bilateral stimulation.
Grafesthesia means the ability to identify the letters or figures drawn by the examiner with the tip of the finger in different areas of the patient's body, while the patient has his eyes closed. The palms of the two hands are usually compared. The numbers/letters must be drawn large enough to occupy almost the entire palm surface. The comparison of the two homologous regions tested is also particularly important in this case. Failure to recognize numbers or letters is called a graph.
Stereognosia refers to the ability to recognize ordinary objects by palpation, by recognizing their shape, texture and size. Ordinary standard objects are the best test items, such as a ball, sheet of paper, small rubber ball, or coins. Patients with normal stereognosis should be able to differentiate the different sizes of some coins.
Patients will identify the object with each hand, one at a time. If they cannot identify it by placing it in one hand, it will move the object into the other hand so you can make a comparison. It is called abnormal hand astereognosia if the patient does not identify the object with it, but can do it with the other hand. It should be noted that comparative assessment will be practiced between the two parts of the body.
Now let's see how to locate sensory anomalies. Peripheral neuropathies are usually gradual, distal and have a symmetrical distribution of the deficit. Although most peripheral neuropathies cause pansensory impairment, altering all types of sensitivity, selective sensory dysfunction may occur, depending on the thickness of the related nerve fiber.
In the case of damage to thin fibers, the typical sign is dysesthesia in the form of a painful burn with reduced perception of stinging pain and thermal sensitivity, but with the maintenance within physiological limits of proprioceptive sensations, motor function and even deep tendinous reflexes. The sense of touch is variablely affected, but when it is spared, the so-called sensory dissociation results.
Unlike small-thickness fiber neuropathies, neuropathies affecting thick fibers are characterized by changes in proprioceptive sensitivity, imbalance, lack of tendinous reflexes, variable motor dysfunction, but most skin sensations are maintained and dysesthesia is minimal or absent.
Paresthesias and dysesthesias have either peripheral or medullary nerve origin and can probably occur by damage to the brain stem, in each of these situations they represent abnormal manifestations of uni or multifocal ectopic discharges of impulses. Isolated paresthesias may not be localizable, but when associated with other signs of neuropathy or myelopathy, the origin of the lesion can be inferred.
The pattern of dissociated sensory deficit, in which the painful sensitivity to pricking and the thermal sensitivity disappears, but the tactile one is maintained, is usually a sign of damage to the spinotalamic tracts in the spinal cord, especially if the deficiency is unilateral and at a higher level of the torso.
Bilateral spinotalamic damage occurs within lesions affecting the central medullary part, for example in the expansion of the ependimar canal in the syringomyely. Sensitive dissociation can also occur in peripheral neuropathies where the related small-thickness skin nerve fibers are predominantly affected. Neuropathies in which sensitive dissociation may occur are leper neuritis, hereditary sensory neuropathies and certain cases of amyloid or diabetic polyneuropathy.
Hemisensitive disorder associated with numbness in that half of the body usually has talamic origin but can also be anterior parietal. If the onset is sudden, the lesion is probably secondary to a small stroke (lacunar infarction), especially if it is localized in the thalamus.
Sometimes, in posterolateral thalamus (PLV) lesions or adjacent white substance, a painful talamic syndrome, also called Dejerine-Roussy syndrome, can occur. This is a persistent severe painful condition in an entire half of my body, sometimes described in terms such as "as if the flesh were ripped off my limbs" or "like an acid immersion of the affected part".
The harlequin-type distribution of sensory disorders, in which part of the face and the opposite side of the body are affected, are located in the lateral bulb, where a small lesion can affect both the homolateral descending trigeminal tract and the ascending spinotalamic beam (side wood), which irritates the arm, mid-body and contralateral lower limb.
In lesions of the parietal lobe, cortical or underlying white substance, the predominant symptoms are neglect and lack of attention towards the contralateral half of the body and the tendency not to use the contralateral hand and arm. Primary sensitivity tests may be normal or minimally modified. Anterior parietal infarction can be presented as a pseudotalamic syndrome, with hemilateral loss of primary sensitivity.
Dysesthesia, or even a feeling of numbness, also occur, except for the special situation of focal sensory attacks. These are generally due to injuries at or near the post-central gyr. Symptoms of focal somatosensitive attacks are usually a combination of numbness and tingling, but more complex sensations such as redness, warmness, perception of movements in their absence or distasteful dysesthetic sensations are also present.
The duration of attacks is variable, they can be transient, can last only a few seconds or persist for several hours. Focal motor manifestations can overlap with sensory attack (clonic reflexes), resulting in generalization of the crisis of loss of consciousness. The probable localization of symptoms is one-sided in the lips, face, fingers or foot, which can diffuse in a Jacksonian manner.
Sometimes symptoms can occur bilaterally, symmetrically, for example in both hands, this being the consequence of the interest of the secondary (unilateral) sensory area located in the rolandic area, in the immediate vicinity of Sylvius' ditch.
That's right, I've completed the paresthesia. I will continue, in the posts that follow, with acute confusion and coma.
Areas of hypoalgesia should be marked from the areas least sensitive to pain, to those that perceive pain almost normally. Thermal sensitivity, both cold and hot, is probably best appreciated by touching the skin for a few seconds with a container full of water at the desired temperature (thermometrically checked). It is gratifying if the patient perceives as warm the container located at 35-36 degrees celsius and as cold the one at 28-32 degrees celsius. Between 28 and 32 degrees celsius most people can distinguish thermal differences of 1 degree celsius, progressively.
Because hot and cold sensitivity is served by different receptors, both types of sensitivity should be tested. The tactile sensitivity is usually tested using a piece of cotton wool or a fine brush of camel hair.
In general, it is good to avoid testing the tactile sensitivity in the hairy skin, due to the depth at which the sensory endings surrounding each hair follicle are located. The patient, who will have his eyes closed, must confirm whenever he feels the tactile stimulus. It can also indicate where he felt the stimulus, although this test also involves a sense of localization.
Proprioception, one of the most important functions of the sensory system, is investigated by testing the perception of the position of the joints. This is usually done first at the level of the halo and then at the level of the fingers. The patient closes his eyes and completely relaxes the examined region.
In the case of the halo, some begin with the neutral position of the haluces and by gently the haluces of the patient between the font and the forefinger, on either side of the halo (not above or below). Haluces is moved a few degrees in both dorsal and plantar direction, the patient must specify whether the movement was up or down.
We need to make sure the patient understands that the direction of the halos is being tested at the time of stopping. A patient who lacks a sense of position at the level of the tested part will have an error rate of 50%, as there are two choices. Responses that are significantly greater than 50% in error should be interpreted with caution.
If errors occur when recognizing the direction of passive movements of the halucus, then other phalanx joints, fist and elbow joints will be tested. Testing of the sense of joint positioning, mainly at the shoulder level, can be carried out by asking the patient to join the two index fingers when the arms are extended and the eyes closed. Normal people can perform this gesture accurately, the error being up to one centimeter.
The vibrating sense is tested with a diapazon, preferably a large one, which vibrates at 128 Hz. The decrease in the amplitude of the vibration of this type of diapazon is slow enough to be useful in quantitative testing, considering that it takes 15 to 20 seconds to decrease to a level below the perceptible threshold.
Vibratory sensitivity is usually investigated at the level of bone protrusions, specifically in the maleolar area of the ankles, rotulian, anterior iliac spine, spiny apophyses of the vertebral bodies, metacarpo-phalangeal joints (finger joints of the hands), ulnar stiloid apophysis, elbow and acromion.
The places of preference in assessing vibrating sensitivity are the forehead and sternum. The examiner can compare the threshold of perception in a particular area of the patient with that which he perceives himself. A rough approximation of the degree of loss of vibrating sense can be obtained by counting the seconds in which the examiner senses vibrations while the patient does not. The patient must be clear that it is necessary to direct his attention to the vibrations produced and not only to the pressure exerted by the root of the diapazon.
Let's continue with the cortical sensibility. The cortical segment of sensitivity is usually tested by assessing discrimination between two points, the localization of tactile stimulus, stereognosia, graphesthesia and simultaneous bilateral stimulation. The modification of these sensory tests, associated with an unchanged primary sensitivity in a conscious and cooperative patient, signifies a lesion of the parietal cortex or of the talamocortical projections to the parietal lobe.
If primary sensitivity is affected, it is not possible to investigate these discriminatory cortical functions. Discrimination between two points shall be tested using a special compass whose tips can be positioned from 2 mm to a few centimeters away and then applied simultaneously to the area to be tested.
Frequently, the test is carried out at the pulp of the fingers (a normal person may perceive the tips of the compass separately, when they are about 3 mm apart). The tongue and lips may perceive two separate points less than 3 mm away, but other regions of the body may have thresholds of discrimination, between two points, of a few centimeters. Symmetrical areas of the body will always be compared, as the deficiency from a specific parietal lesion is homolateral. This applies to all investigations of the cortical sensitivity segment.
The localization of tactile sensations is done by requiring the patient to close his eyes and the examiner exerts a slight pressure with his fingertips in an area that the person examined must specify. It is customary for the patient to indicate with the tip of his finger the place that the doctor touched.
Simultaneous bilateral stimulation of the homologous areas (e.g. the dorsal part of the hands) is performed to determine whether tactile perception is considerably reduced in one part of the body compared to the other. The phenomenon is known as extinction at simultaneous bilateral stimulation.
Grafesthesia means the ability to identify the letters or figures drawn by the examiner with the tip of the finger in different areas of the patient's body, while the patient has his eyes closed. The palms of the two hands are usually compared. The numbers/letters must be drawn large enough to occupy almost the entire palm surface. The comparison of the two homologous regions tested is also particularly important in this case. Failure to recognize numbers or letters is called a graph.
Stereognosia refers to the ability to recognize ordinary objects by palpation, by recognizing their shape, texture and size. Ordinary standard objects are the best test items, such as a ball, sheet of paper, small rubber ball, or coins. Patients with normal stereognosis should be able to differentiate the different sizes of some coins.
Patients will identify the object with each hand, one at a time. If they cannot identify it by placing it in one hand, it will move the object into the other hand so you can make a comparison. It is called abnormal hand astereognosia if the patient does not identify the object with it, but can do it with the other hand. It should be noted that comparative assessment will be practiced between the two parts of the body.
Now let's see how to locate sensory anomalies. Peripheral neuropathies are usually gradual, distal and have a symmetrical distribution of the deficit. Although most peripheral neuropathies cause pansensory impairment, altering all types of sensitivity, selective sensory dysfunction may occur, depending on the thickness of the related nerve fiber.
In the case of damage to thin fibers, the typical sign is dysesthesia in the form of a painful burn with reduced perception of stinging pain and thermal sensitivity, but with the maintenance within physiological limits of proprioceptive sensations, motor function and even deep tendinous reflexes. The sense of touch is variablely affected, but when it is spared, the so-called sensory dissociation results.
Unlike small-thickness fiber neuropathies, neuropathies affecting thick fibers are characterized by changes in proprioceptive sensitivity, imbalance, lack of tendinous reflexes, variable motor dysfunction, but most skin sensations are maintained and dysesthesia is minimal or absent.
Paresthesias and dysesthesias have either peripheral or medullary nerve origin and can probably occur by damage to the brain stem, in each of these situations they represent abnormal manifestations of uni or multifocal ectopic discharges of impulses. Isolated paresthesias may not be localizable, but when associated with other signs of neuropathy or myelopathy, the origin of the lesion can be inferred.
The pattern of dissociated sensory deficit, in which the painful sensitivity to pricking and the thermal sensitivity disappears, but the tactile one is maintained, is usually a sign of damage to the spinotalamic tracts in the spinal cord, especially if the deficiency is unilateral and at a higher level of the torso.
Bilateral spinotalamic damage occurs within lesions affecting the central medullary part, for example in the expansion of the ependimar canal in the syringomyely. Sensitive dissociation can also occur in peripheral neuropathies where the related small-thickness skin nerve fibers are predominantly affected. Neuropathies in which sensitive dissociation may occur are leper neuritis, hereditary sensory neuropathies and certain cases of amyloid or diabetic polyneuropathy.
Hemisensitive disorder associated with numbness in that half of the body usually has talamic origin but can also be anterior parietal. If the onset is sudden, the lesion is probably secondary to a small stroke (lacunar infarction), especially if it is localized in the thalamus.
Sometimes, in posterolateral thalamus (PLV) lesions or adjacent white substance, a painful talamic syndrome, also called Dejerine-Roussy syndrome, can occur. This is a persistent severe painful condition in an entire half of my body, sometimes described in terms such as "as if the flesh were ripped off my limbs" or "like an acid immersion of the affected part".
The harlequin-type distribution of sensory disorders, in which part of the face and the opposite side of the body are affected, are located in the lateral bulb, where a small lesion can affect both the homolateral descending trigeminal tract and the ascending spinotalamic beam (side wood), which irritates the arm, mid-body and contralateral lower limb.
In lesions of the parietal lobe, cortical or underlying white substance, the predominant symptoms are neglect and lack of attention towards the contralateral half of the body and the tendency not to use the contralateral hand and arm. Primary sensitivity tests may be normal or minimally modified. Anterior parietal infarction can be presented as a pseudotalamic syndrome, with hemilateral loss of primary sensitivity.
Dysesthesia, or even a feeling of numbness, also occur, except for the special situation of focal sensory attacks. These are generally due to injuries at or near the post-central gyr. Symptoms of focal somatosensitive attacks are usually a combination of numbness and tingling, but more complex sensations such as redness, warmness, perception of movements in their absence or distasteful dysesthetic sensations are also present.
The duration of attacks is variable, they can be transient, can last only a few seconds or persist for several hours. Focal motor manifestations can overlap with sensory attack (clonic reflexes), resulting in generalization of the crisis of loss of consciousness. The probable localization of symptoms is one-sided in the lips, face, fingers or foot, which can diffuse in a Jacksonian manner.
Sometimes symptoms can occur bilaterally, symmetrically, for example in both hands, this being the consequence of the interest of the secondary (unilateral) sensory area located in the rolandic area, in the immediate vicinity of Sylvius' ditch.
That's right, I've completed the paresthesia. I will continue, in the posts that follow, with acute confusion and coma.
Remember
that the weekend is coming and you need to rest and/ or have
fun!!!
Dorin, Merticaru