STUDY - Technical - New Dacian's Medicine
Paresthesia
and other sensory disorders
(1)
Translation Draft
Physiological somatic sensations are a continuous process involving considerable and continuous activity of the nervous system. This activity is little aware or appreciated exactly. In contrast, sensory impairment, especially pain and paresthesia can be perceived intensely, are alarming and tenacious, monopolizing attention.
Thus, these sensory abnormalities quickly cause the patient to contact the doctor (when abnormal sensations are perceived as painful, medical help is sought even earlier). And the doctor must have a set of knowledge that allows him to appreciate abnormal sensations, estimate their possible origin and identify their consequences.
In this case, the most useful position is to "perceive" positive and/ or negative manifestations (it is useful to divide these sensitive phenomena into positive and/ or negative). Positive phenomena include tingling, numbness, stinging, tightness, nagging sensations (similar to an electric shock), pain and various sensations compared to stab wounds, torsion, traction, tightening, burning, cauterization, electric current and skin.
This is often how patients describe their suffering, and these sensations may or may not be perceived as painful. It is considered that the physiopathological basis of positive sensory manifestations is the ectopic generation of pulse salvos at the level of areas with low neural threshold along the sensory pathways, both in peripheral and central sensory fibers. Such related ectopic signals, which do not come from peripheral nerve receptors, determine the quality of the perceived abnormal sensations, depending on the number, frequency and distribution of the impulses, as well as the type and function of the nerve fibers in which they occur.
Positive phenomena are an intensified activity within sensory fibers and are therefore not necessarily associated with an obvious sensory deficiency during the examination. Negative phenomena occur through the loss of sensory functions and are characterized by the diminution or absence of sensations, frequently felt as numbness, in a particular territory.
Unlike positive manifestations, negative phenomena are accompanied by pathological changes when examining sensitivity. In diseases involving peripheral sensitivity, in order for the sensory deficiency to be revealed, it is estimated that at least half of the fibres that irritate an area must disappear or be inoperable.
This estimate probably varies depending on how fast the sensory fibers have become inoperable. if their impairment has been slow and chronic, the lack of skin sensitivity may go unnoticed by the patient and may be difficult to highlight in the clinical examination, although the number of functional sensory fibers is much reduced.
Sensitive anomalies with rapid evolution usually take the form of positive manifestations of a certain type, being more quickly identified subjectively than insidious decommissioning. Subclinical degrees of sensory changes that cannot be evidenced by the specific objective examination can be demonstrated by driving studies at the level of the sensory nerves or by the potential evoked somatosensitive cerebral.
Sensitive symptoms can be positive or negative, but the signs sensitive to examination are always negative phenomena.
Let's do a review of some terms now! Paresthesia and dysesthesia are terms used for positive phenomena (sensory symptoms). Paresthesia implies that normal sensation is perceived in the absence of an apparent stimulus, while dysesthesia is a more general term used to describe all types of positive sensations, whether the stimulus is obvious or not.
The abnormalities observed in the objective examination are referred to as hypesthesia or hypoesthesia (reduction of skin sensations in a certain type of test, such as pressure, mild touch, warm-cold stimuli), anesthesia (absence of any skin sensation in the same stimuli, even that of stinging) and hypoalgesia (which refers to the loss of painful perception, i.e. nociceptive, as is the sensation produced by pricking with an ace).
Hyperesthesia means an exaggerated perception of medium stimuli (e.g. a slight touch or caressing of the skin). similarly, alodinia describes the situation in which a common painless stimulus is perceived as a painful, even unbearable sensation. An example is the pain felt when applying a diapazon skin.
Hyperalgesia denotes an exaggerated response to a harmful stimulus, and hyperpathy is a generic term that includes all phenomena described by hyperesthesia, alodinia and hyperalgesia. The impairment of deep sensations from the neuromuscular zones, tendons and joints influences proprioception (the meaning of the position).
Manifestations include loss of balance, especially when closing eyes or in the dark, clumsiness in performing fine movements and instability when walking, famous as sensory ataxia. Other objective signs include the reduction or absence of joint position and vibrating sensitivity and the absence of deep tendon reflexes in the affected limbs.
The Romberg sign is positive, which means that the patient swings or falls when asked to stand with his eyes closed and his heels glued. In severe allowances involving deep sensitivity, the patient cannot stand or walk without help, sometimes he cannot even sit without support. Continuous involuntary movements, sometimes vermicular, of the hands and arms occur, especially when closing the eyes, movements that are called pseudoatetosis (these patients have a severe disability).
Normal sensory perceptions are the next step in this job. The related skin innervation is served by a wide variety of receptors, which include both free nerve endings (nociceptors and thermoreceptors) and encapsulated ones (mechanoreceptors). Each possesses its own range of sensitivities to specific stimuli, size and distinct character of receiving fields and adaptive qualities.
Most of the knowledge about these receptors was accumulated through the development of techniques for the study of distinct intact intraneural nerve fibers in waking, unanaesthetised subjects. It is possible not only to make records at the level of single nerve fiber, large or small, but also to stimulate them in isolation. A unique impulse, produced either by natural stimuli or by electrical microstimulation, at the level of a thick fibre related to myelinized, can be both perceived and localized.
The related fibers from the peripheral nerve trunks cross the posterior roots and enter the medullary dorsal horns. Hence, polysynaptic projections of smaller fibres (amyelin and low myelin), which generally serve nociceptive and thermal sensitivity cross and have an upward trajectory within the counterlateral spinotalamic beam, along the spinal cord, the brain stem, up to the postero-lateral ventral nucleus (VPL) of the thalamus and finally is projected into the postcentral gyrus of the parietal cortex (this being the spinotalal pathway).
The thicker fibers, serving tactile and proprioceptive sensitivity and kinesthesia, project rostalc at the level of homolateral posterior medullary cords and finally achieve their first synapse in the gracil or cuate shells of the lower bulb. The second neuron crosses and has an upward trajectory through the medial wood, located medial in the bulb, pontine and mesencephalic segment, then makes synapse in the VPL. The third neuron is projected into the parietal cortex, the whole system being called the term lemnisc.
Although the type and functions of the fibers that make up the spinotalamic and woodismal systems are relatively well studied, it has been found that many other fibers, especially tactile, pressure and proprioceptive ones, have upward trajectories, without being grouped into beams, through homo and contralateral medullary anterolateral cords. These anatomical specifications explain why a patient with a known complete lesion of the posterior medullary cords has a minimal sensory deficiency on examination.
Let's finalize this post with a brief description of the sensitivity review. The first step in examining the somatosensitive system is to carry out tests for the investigation of primary sensitivity, which conventionally includes the sensitivity of painful, tactile, vibratory, thermal (warm and cold) and joint position. A few general principles need to be taken into account.
First, the examiner should not forget that it depends on the subjectivity of the patient which, in turn, depends on the state of wakefulness, the motivation and intelligence of the patient, as well as the doctor's ability to formulate clear commands. In a stunned or obnucable patient, the sensitive examination is limited to observing the sudden withdrawal and complexity of the defensive movements that the patient performs in response to pinches or other harmful stimuli. in the patient in a vigiled but non-cooperative state, it is often possible to form an opinion on the proprioceptive function by recording the best performance of the patient in performing movements that require balance and precision.
Skin sensations cannot be investigated. Secondly, the sensitivity examination should be postponed if the patient is tired. A brief assessment is sufficient until the more extensive examination is carried out after the patient has rested. Thirdly, the neurosensitive examination of a patient without neurological charges will be more cursory and will consist of testing the painful perception (stinging), tactile and vibrating of the hands and feet, associated with the assessment of the orthostatic position and gait, including through the Romberg maneuver, which also verifies the integrity of the motor and cerebellar system. Fourth, patients will be tested after closing their eyes for both primary sensitivity and cortical sensory function.
Physiological somatic sensations are a continuous process involving considerable and continuous activity of the nervous system. This activity is little aware or appreciated exactly. In contrast, sensory impairment, especially pain and paresthesia can be perceived intensely, are alarming and tenacious, monopolizing attention.
Thus, these sensory abnormalities quickly cause the patient to contact the doctor (when abnormal sensations are perceived as painful, medical help is sought even earlier). And the doctor must have a set of knowledge that allows him to appreciate abnormal sensations, estimate their possible origin and identify their consequences.
In this case, the most useful position is to "perceive" positive and/ or negative manifestations (it is useful to divide these sensitive phenomena into positive and/ or negative). Positive phenomena include tingling, numbness, stinging, tightness, nagging sensations (similar to an electric shock), pain and various sensations compared to stab wounds, torsion, traction, tightening, burning, cauterization, electric current and skin.
This is often how patients describe their suffering, and these sensations may or may not be perceived as painful. It is considered that the physiopathological basis of positive sensory manifestations is the ectopic generation of pulse salvos at the level of areas with low neural threshold along the sensory pathways, both in peripheral and central sensory fibers. Such related ectopic signals, which do not come from peripheral nerve receptors, determine the quality of the perceived abnormal sensations, depending on the number, frequency and distribution of the impulses, as well as the type and function of the nerve fibers in which they occur.
Positive phenomena are an intensified activity within sensory fibers and are therefore not necessarily associated with an obvious sensory deficiency during the examination. Negative phenomena occur through the loss of sensory functions and are characterized by the diminution or absence of sensations, frequently felt as numbness, in a particular territory.
Unlike positive manifestations, negative phenomena are accompanied by pathological changes when examining sensitivity. In diseases involving peripheral sensitivity, in order for the sensory deficiency to be revealed, it is estimated that at least half of the fibres that irritate an area must disappear or be inoperable.
This estimate probably varies depending on how fast the sensory fibers have become inoperable. if their impairment has been slow and chronic, the lack of skin sensitivity may go unnoticed by the patient and may be difficult to highlight in the clinical examination, although the number of functional sensory fibers is much reduced.
Sensitive anomalies with rapid evolution usually take the form of positive manifestations of a certain type, being more quickly identified subjectively than insidious decommissioning. Subclinical degrees of sensory changes that cannot be evidenced by the specific objective examination can be demonstrated by driving studies at the level of the sensory nerves or by the potential evoked somatosensitive cerebral.
Sensitive symptoms can be positive or negative, but the signs sensitive to examination are always negative phenomena.
Let's do a review of some terms now! Paresthesia and dysesthesia are terms used for positive phenomena (sensory symptoms). Paresthesia implies that normal sensation is perceived in the absence of an apparent stimulus, while dysesthesia is a more general term used to describe all types of positive sensations, whether the stimulus is obvious or not.
The abnormalities observed in the objective examination are referred to as hypesthesia or hypoesthesia (reduction of skin sensations in a certain type of test, such as pressure, mild touch, warm-cold stimuli), anesthesia (absence of any skin sensation in the same stimuli, even that of stinging) and hypoalgesia (which refers to the loss of painful perception, i.e. nociceptive, as is the sensation produced by pricking with an ace).
Hyperesthesia means an exaggerated perception of medium stimuli (e.g. a slight touch or caressing of the skin). similarly, alodinia describes the situation in which a common painless stimulus is perceived as a painful, even unbearable sensation. An example is the pain felt when applying a diapazon skin.
Hyperalgesia denotes an exaggerated response to a harmful stimulus, and hyperpathy is a generic term that includes all phenomena described by hyperesthesia, alodinia and hyperalgesia. The impairment of deep sensations from the neuromuscular zones, tendons and joints influences proprioception (the meaning of the position).
Manifestations include loss of balance, especially when closing eyes or in the dark, clumsiness in performing fine movements and instability when walking, famous as sensory ataxia. Other objective signs include the reduction or absence of joint position and vibrating sensitivity and the absence of deep tendon reflexes in the affected limbs.
The Romberg sign is positive, which means that the patient swings or falls when asked to stand with his eyes closed and his heels glued. In severe allowances involving deep sensitivity, the patient cannot stand or walk without help, sometimes he cannot even sit without support. Continuous involuntary movements, sometimes vermicular, of the hands and arms occur, especially when closing the eyes, movements that are called pseudoatetosis (these patients have a severe disability).
Normal sensory perceptions are the next step in this job. The related skin innervation is served by a wide variety of receptors, which include both free nerve endings (nociceptors and thermoreceptors) and encapsulated ones (mechanoreceptors). Each possesses its own range of sensitivities to specific stimuli, size and distinct character of receiving fields and adaptive qualities.
Most of the knowledge about these receptors was accumulated through the development of techniques for the study of distinct intact intraneural nerve fibers in waking, unanaesthetised subjects. It is possible not only to make records at the level of single nerve fiber, large or small, but also to stimulate them in isolation. A unique impulse, produced either by natural stimuli or by electrical microstimulation, at the level of a thick fibre related to myelinized, can be both perceived and localized.
The related fibers from the peripheral nerve trunks cross the posterior roots and enter the medullary dorsal horns. Hence, polysynaptic projections of smaller fibres (amyelin and low myelin), which generally serve nociceptive and thermal sensitivity cross and have an upward trajectory within the counterlateral spinotalamic beam, along the spinal cord, the brain stem, up to the postero-lateral ventral nucleus (VPL) of the thalamus and finally is projected into the postcentral gyrus of the parietal cortex (this being the spinotalal pathway).
The thicker fibers, serving tactile and proprioceptive sensitivity and kinesthesia, project rostalc at the level of homolateral posterior medullary cords and finally achieve their first synapse in the gracil or cuate shells of the lower bulb. The second neuron crosses and has an upward trajectory through the medial wood, located medial in the bulb, pontine and mesencephalic segment, then makes synapse in the VPL. The third neuron is projected into the parietal cortex, the whole system being called the term lemnisc.
Although the type and functions of the fibers that make up the spinotalamic and woodismal systems are relatively well studied, it has been found that many other fibers, especially tactile, pressure and proprioceptive ones, have upward trajectories, without being grouped into beams, through homo and contralateral medullary anterolateral cords. These anatomical specifications explain why a patient with a known complete lesion of the posterior medullary cords has a minimal sensory deficiency on examination.
Let's finalize this post with a brief description of the sensitivity review. The first step in examining the somatosensitive system is to carry out tests for the investigation of primary sensitivity, which conventionally includes the sensitivity of painful, tactile, vibratory, thermal (warm and cold) and joint position. A few general principles need to be taken into account.
First, the examiner should not forget that it depends on the subjectivity of the patient which, in turn, depends on the state of wakefulness, the motivation and intelligence of the patient, as well as the doctor's ability to formulate clear commands. In a stunned or obnucable patient, the sensitive examination is limited to observing the sudden withdrawal and complexity of the defensive movements that the patient performs in response to pinches or other harmful stimuli. in the patient in a vigiled but non-cooperative state, it is often possible to form an opinion on the proprioceptive function by recording the best performance of the patient in performing movements that require balance and precision.
Skin sensations cannot be investigated. Secondly, the sensitivity examination should be postponed if the patient is tired. A brief assessment is sufficient until the more extensive examination is carried out after the patient has rested. Thirdly, the neurosensitive examination of a patient without neurological charges will be more cursory and will consist of testing the painful perception (stinging), tactile and vibrating of the hands and feet, associated with the assessment of the orthostatic position and gait, including through the Romberg maneuver, which also verifies the integrity of the motor and cerebellar system. Fourth, patients will be tested after closing their eyes for both primary sensitivity and cortical sensory function.
Today
is Holiday Thursday, so everything is going well!
Dorin, Merticaru