A hearing test provides an evaluation of the sensitivity of a person's sense of hearing and is most performed by an audiologist using an audiometer. An audiometer is used to determine a person's hearing sensitivity at different frequencies. There are other hearing tests as well, e.g. Weber Rinne test. Prior to the hearing test itself, the ears of the client are examined with an otoscope to make sure they are free of wax, that the eardrum is intact, the ears are not infected, the middle ear is free of fluid; the most common reasons to develop hearing loss due to genetic disorder, ageing problems, exposure to noise pollution, birth complications, trauma to the ear, certain medications or toxins. The standard and most common type of hearing test is pure tone audiometry, which measures the air and bone conduction thresholds for each ear in a set of 8 standard frequencies from 250Hz to 8000Hz; the test is conducted in a sound booth using either a pair of foam inserts or supraural headphones connected to an external audiometer.
The result of the test is an audiogram diagram which plots a person's hearing sensitivity at the tested frequencies. On an audiogram an "x" plot represents the softest threshold heard at each specific frequency in the left ear, an "o" plot represents the softest threshold heard at ech specific frequency in the right ear. There is a high frequency version of the test which tests frequencies over 8000Hz to 16000Hz which may be employed in special circumstances. A complete hearing evaluation involves several other tests as well. In order to determine what kind of hearing loss is present, a bone conduction hearing test is administered. In this test, a vibrating tuning fork is placed on the mastoid process; when the patient can no longer feel/hear the vibration, the tuning fork is held in front of the ear. If they cannot, there is conductive hearing loss in that ear. Additionally, the tuning fork is placed on the forehead; the patient is asked if the sound is localised in the centre of the head or whether it is louder in either ear.
If there is conductive hearing loss, it is to be louder in the affected ear. This test helps the audiologist determine whether the hearing loss is conductive or sensorineural or neural - caused by a problem in the auditory nerve or auditory pathways/cortex of the brain; the Hearing in Noise Test measures a person's ability to hear speech in noise. In the test, the patient is required to repeat sentences both in a quiet environment and with competing noise being presented from different directions. More there are four conditions: sentences with no competing noise, sentences with competing noise presented directly in front of the patient, noise presented at 90° to the right of the patient, noise presented at 90° to the left of the patient; the test measures signal to noise ratio for the different conditions which corresponds to how loud the sentences needed to be played above the noise so that the patient can repeat them 50% of the time. The Words-in-Noise Test uses monosyllabic words presented at seven different signal to noise ratios with masking noise - speech spectrum noise.
The WIN test will yield a score for a person's ability to understand speech in a noisy background. Unlike a pure-tone audiogram, the WIN test may provide a more functional test of a person's hearing in a situation, to occur; the Modified Rhyme Test is defined in the American National Standard ANSI S3.2 Methods for Measuring the Intelligibility of Speech Over Communication Systems. The method consists of 50 sets of six monosyllabic words that differ in final consonant; the listener is presented with the on of the words in the couplet preceded by a phrase, "You will mark the word ___". The six words that rhyme are presented to the listener to select what they believe to be the correct answer; the MRT has been extensively used by the US Air Force to test the performance of different communication systems, which include a noise interference component. If a condition achieves a score of 80% correct responses or better, an acceptable performance level; the audiologist or hearing instrument specialist may conduct speech tests, wherein the patient repeats the words he or she hears.
In addition, a test called a tympanogram is done. In this test, a small probe is placed in the ear and the air pressure in the ear canal is varied; this test tells the audiologist how well the eardrum and other structures in the middle ear are working. The ear canal volume indicates; the middle ear pressure indicates. Compliance measurement indicates how well ossicles are moving; the last test the audiologist may perform is an acoustic reflex test. In this test a probe is placed in the ear and a loud tone, greater than 70 dBSPL, is produced; the test measures the reflexive contraction of the stapedius muscle, important in protecting the ear from loud noises, such as a person's own speech which may be 90 dBSPL at the eardrum. This test can be used to give information about the vestibular and facial nerves and indicate if a lesion may be present. Online Hearing Test (Au
The Weber test is a quick screening test for hearing. It can detect unilateral sensorineural hearing loss; the test is named after Ernst Heinrich Weber. Conductive hearing ability is mediated by the middle ear composed of the ossicles: incus, stapes. Sensorineural hearing ability is mediated by the inner ear composed of the cochlea with its internal basilar membrane and attached cochlear nerve; the outer ear consisting of the pinna, ear canal, ear drum or tympanic membrane transmits sounds to the middle ear but does not contribute to the conduction or sensorineural hearing ability save for hearing transmissions limited by cerumen impaction. The Weber test has had its value as a screening test questioned in the literature; the Weber and the Rinne test are performed together with the results of each combined to determine the location and nature of any hearing losses detected. In the Weber test a vibrating tuning fork is placed in the middle of the forehead, above the upper lip under the nose over the teeth, or on top of the head equi-distant from the patient's ears on top of thin skin in contact with the bone.
The patient is asked to report. A normal weber test has a patient reporting the sound heard in both sides. In an affected patient, if the defective ear hears the Weber tuning fork louder, the finding indicates a conductive hearing loss in the defective ear. In an affected patient, if the normal ear hears the tuning fork sound better, there is sensorineural hearing loss on the other ear. However, the aforegoing presumes one knows in advance which ear is defective and, normal and the testing is being done to characterize the type, conductive or sensorineural, of hearing loss, occurring. In the case where the patient is unaware or has acclimated to their hearing loss, the clinician has to use the Rinne test in conjunction with the Weber to characterize and localize any deficits; that is, an abnormal Weber test is only able to tell the clinician that there is a conductive loss in the ear which hears better or that there is a sensorineural loss in the ear which does not hear as well. For the Rinne test, a vibrating tuning fork is placed on the mastoid process behind each ear until sound is no longer heard.
Without re-striking the fork, the fork is quickly placed just outside the ear with the patient asked to report when the sound caused by the vibration is no longer heard. A normal or positive Rinne test is when sound is still heard when the tuning fork is moved to air near the ear, indicating that AC is equal or greater than. Therefore, AC > BC. In conductive hearing loss, bone conduction is better than air or BC > AC, a negative Rinne, the patient will report that they do not hear the fork once it is moved. The Rinne test is not ideal for distinguishing sensorineural hearing loss, as both sensorineural hearing loss and normal hearing report a positive Rinne test. In a normal patient, the Weber tuning fork sound is heard loudly in both ears, with no one ear hearing the sound louder than the other. A patient with symmetrical hearing loss will hear the Weber tuning fork sound well, with diagnostic utility only in asymmetric hearing losses. In a patient with hearing loss, the Weber tuning fork sound is heard louder in one ear than the other.
This clinical finding should be confirmed by repeating the procedure and having the patient occlude one ear with a finger. The results of both tests are noted and compared accordingly below to localize and characterize the nature of any detected hearing losses. Note: the Weber and Rinne are screening tests that are not replacements for formal audiometry hearing tests. A patient with a unilateral conductive hearing loss would hear the tuning fork loudest in the affected ear; this is because the ear with the conductive hearing loss is only receiving input from the bone conduction and no air conduction, the sound is perceived as louder in that ear. This finding is because the conduction problem of the middle ear masks the ambient noise of the room, while the well-functioning inner ear picks the sound up via the bones of the skull, causing it to be perceived as a louder sound in the affected ear. Another theory, however, is based on the occlusion effect described by Tonndorf et al. in 1966. Lower frequency sounds.
If an occlusion is present, the sound cannot escape and appears louder on the ear with the conductive hearing loss. Conductive hearing loss can be mimicked by plugging one ear with a finger and performing the Rinne and Weber tests, which will help clarify the above. Humming a constant note and plugging one ear is a good way to mimic the findings of the Weber test in conductive hearing loss; the simulation of the Weber test is the basis for the Bing test. If air conduction is intact on both sides, the patient will report a quieter sound in the ear with
The vestibulo-ocular reflex is a reflex, where activation of the vestibular system causes eye movement. This reflex functions to stabilize images on the retinas during head movement by producing eye movements in the direction opposite to head movement, thus preserving the image on the center of the visual field. For example, when the head moves to the right, the eyes move to the left, vice versa. Since slight head movement is present all the time, VOR is necessary for stabilizing vision: patients whose VOR is impaired find it difficult to read using print, because they cannot stabilize the eyes during small head tremors, because damage to the VOR can cause vestibular nystagmus; the VOR does not depend on visual input. It can be elicited by caloric stimulation of the inner ear, works in total darkness or when the eyes are closed. However, in the presence of light, the fixation reflex is added to the movement. In other animals, the organs that coordinate balance and motor coordination do not operate independently from the organs that control the eyes.
A fish, for instance, moves its eyes by reflex. Humans have semicircular canals, neck muscle "stretch" receptors, the utricle. Though the semicircular canals cause most of the reflexes which are responsive to acceleration, the maintaining of balance is mediated by the stretch of neck muscles and the pull of gravity on the utricle of the inner ear; the VOR has both translational aspects. When the head rotates about any axis distant visual images are stabilized by rotating the eyes about the same axis, but in the opposite direction; when the head translates, for example during walking, the visual fixation point is maintained by rotating gaze direction in the opposite direction, by an amount that depends on distance. The VOR is driven by signals from the vestibular apparatus in the inner ear; the semicircular canals detect head rotation and drive the rotational VOR, whereas the otoliths detect head translation and drive the translational VOR. The main "direct path" neural circuit for the horizontal rotational VOR is simple.
It starts in the vestibular system, where semicircular canals get activated by head rotation and send their impulses via the vestibular nerve through the vestibular ganglion and end in the vestibular nuclei in the brainstem. From these nuclei, fibers cross to the contralateral cranial nerve VI nucleus. There they synapse with 2 additional pathways. One pathway projects directly to the lateral rectus of the eye via the abducens nerve. Another nerve tract projects from the abducens nucleus by the medial longitudinal fasciculus to the contralateral oculomotor nucleus, which contains motorneurons that drive eye muscle activity activating the medial rectus muscle of the eye through the oculomotor nerve. Another pathway directly projects from the vestibular nucleus through the ascending tract of Dieters to the ipsilateral medial rectus motoneuron. In addition there are inhibitory vestibular pathways to the ipsilateral abducens nucleus; however no direct vestibular neuron to medial rectus motoneuron pathway exists.
Similar pathways exist for the vertical and torsional components of the VOR. In addition to these direct pathways, which drive the velocity of eye rotation, there is an indirect pathway that builds up the position signal needed to prevent the eye from rolling back to center when the head stops moving; this pathway is important when the head is moving because here position signals dominate over velocity signals. David A. Robinson discovered that the eye muscles require this dual velocity-position drive, proposed that it must arise in the brain by mathematically integrating the velocity signal and sending the resulting position signal to the motoneurons. Robinson was correct: the'neural integrator' for horizontal eye position was found in the nucleus prepositus hypoglossi in the medulla, the neural integrator for vertical and torsional eye positions was found in the interstitial nucleus of Cajal in the midbrain; the same neural integrators generate eye position for other conjugate eye movements such as saccades and smooth pursuit.
For instance, if the head is turned clockwise as seen from above excitatory impulses are sent from the semicircular canal on the right side via the vestibular nerve through Scarpa's ganglion and end in the right vestibular nuclei in the brainstem. From this nuclei excitatory fibres cross to the left abducens nucleus. There they stimulate the lateral rectus of the left eye via the abducens nerve. In addition, by the medial longitudinal fasciculus and oculomotor nuclei, they activate the medial rectus muscles on the right eye; as a result, both eyes will turn counter-clockwise. Furthermore, some neurons from the right vestibular nucleus directly stimulate the right medial rectus motoneurons, inhibits the right abducens nucleus; the vestibulo-ocular reflex needs to be fast: for clear vision, head movement must be compensated immediately. To achieve clear vision, signals from the semicircular canals are sent as directly as possible to the eye muscles: the connection involves only three neurons, is correspondingly called the three neuron arc.
Using these direct connections, eye movements lag the head movements by less than 10 ms, thus the vestibulo-ocular reflex is one of the fastest reflexes in the human body. During head-free pursuit of moving targets, the VOR is counterproductive to the goal of reducing retinal offset. Research indicates that th
In biomechanics, balance is an ability to maintain the line of gravity of a body within the base of support with minimal postural sway. Sway is the horizontal movement of the centre of gravity when a person is standing still. A certain amount of sway is essential and inevitable due to small perturbations within the body or from external triggers. An increase in sway is not an indicator of dysfunctional balance so much as it is an indicator of decreased sensorimotor control. Maintaining balance requires coordination of input from multiple sensory systems including the vestibular and visual systems. Vestibular system: sense organs that regulate equilibrium. There are environmental factors that can affect balance such as light conditions, floor surface changes, alcohol and ear infection. There are balance impairments associated with aging. Age-related decline in the ability of the above systems to receive and integrate sensory information contributes to poor balance in older adults; as a result, the elderly are at an increased risk of falls.
In fact, one in three adults aged 65 and over will fall each year. In the case of an individual standing upright, the limit of stability is defined as the amount of postural sway at which balance is lost and corrective action is required. Body sway can occur in all planes of motion, which make it an difficult ability to rehabilitate. There is strong evidence in research showing that deficits in postural balance is related to the control of medial-lateral stability and an increased risk of falling. To remain balanced, a person standing must be able to keep the vertical projection of their center of mass within their base of support, resulting in little medial-lateral or anterior-posterior sway. Ankle sprains are one of the most occurring injuries among athletes and physically active people; the most common residual disability post ankle sprain is instability along with body sway. Mechanical instability includes insufficient stabilizing structures and mobility that exceed physiological limits. Functional instability involves a feeling of giving way of the ankle.
Nearly 40 % of patients with ankle sprains suffer from an increase in body sway. Injury to the ankle causes impaired postural control. Individuals with muscular weakness, occult instability, decreased postural control are more susceptible to ankle injury than those with better postural control. Balance can be affected in individuals with neurological conditions. People who suffer a stroke or spinal cord injury for example, can struggle with this ability. Impaired balance is associated with future function and recovery after a stroke, is the strongest predictor of falls. Another population where balance is affected is Parkinson's disease patients. A study done by Nardone and Schieppati showed that individuals with Parkinson's disease problems in balance have been related to a reduced limit of stability and an impaired production of anticipatory motor strategies and abnormal calibration. Balance can be negatively affected in a normal population through fatigue in the musculature surrounding the ankles and hips.
Studies have found, that muscle fatigue around the hips and knees have a greater effect on postural stability. It is thought that muscle fatigue leads to a decreased ability to contract with the correct amount of force or accuracy; as a result and kinesthetic feedback from joints are altered so that conscious joint awareness may be negatively effected. Since balance is a key predictor of recovery and is required in so many of our activities of daily living, it is introduced into treatment plans by physiotherapists and occupational therapists when dealing with geriatrics, patients with neurological conditions, or others whom they have determined it to be beneficial. Balance training in stroke patients has been supported in the literature. Methods used and proven to be effective for this population include sitting or standing balance practice with various progressions including reaching, variations in base of support, use of tilt boards, gait training varying speed, stair climbing exercises. Another method to improve balance is perturbation training, an external force applied to a person's center of mass in an attempt to move it from the base of support.
The type of training should be determined by a physiotherapist and will depend on the nature and severity of the stroke, stage of recovery, the patient's abilities and impairments after the stroke. Populations such as the elderly, children with neuromuscular diseases, those with motor deficits such as chronic ankle instability have all been studied and balance training has been shown to result in improvements in postural sway and improved “one-legged stance balance” in these groups; the effects of balance training can be measured by
Tone decay test
The tone decay test is used in audiology to detect and measure auditory fatigue. It was developed by Raymond Carhart in 1957. In people with normal hearing, a tone whose intensity is only above their absolute threshold of hearing can be heard continuously for 60 seconds; the tone decay test produces a measure of the "decibels of decay", i.e. the number of decibels above the patient's absolute threshold of hearing that are required for the tone to be heard for 60 seconds. A decay of between 15 and 20 decibels is indicative of cochlear hearing loss. A decay of more than 25 decibels is indicative of damage to the vestibulocochlear nerve. A tone at the frequency of 4000 Hz is presented for 60 seconds at an intensity of 5 decibels above the patient's absolute threshold of hearing. If the patient stops hearing the tone before 60 seconds, the intensity level is increased by another 5 decibels with the procedure repeated until the tone can be heard for the full 60 seconds or until no decibel level can be found where the tone can be heard for the full 60 seconds.
The resultant measure is given as the decibels of decay. TD is a powerful diagnostic procedure for RetroCochlearPathology. However, It is only one of the tests of battery, considered sensitive for differential diagnosis between Cochlear Pathology and Retro Cochlear Pathology. According to Rosenberg, 1958: 0-5 dB Decay - Normal or Conductive 10-15 dB Decay - Mild 20-25 dB Decay - Moderate 30->35 dB Decay - Marked Decay Marked tone decay always indicates RCP. Glaslow, 1968 stated. Tillman, 1969 agreed that patients with RCP have TD exceeding 30 dB. However, at the same time it would be dangerous to assume that anyone with 30 dB decay, has RCP. While everyone with less than this amount, does not have. A more predictive way of looking at TD is that each dB of decay above 15 dB, should raise the suspicion that RCP lesion may exist; the greater the TD and the number of frequencies involved the low frequencies, there is greater possibility of serious pathology. The index of suspicion should be raised if the rate of decay does not diminish with increased stimulus intensity.
Patients with acoustic tumor exhibit extreme an complete TD. However, tumor size appears to be related to the severity of symptoms. Partial or complete TD was found in 60% of tumors classified as large, while, 40% of tumor is classified as small. Fowler noted that equal loudness between the recruiting impaired ear with normal ear can be achieved only with larger sensation levels to the normal ear. E.g. A tone at SL of 60 dB in normal ear and 30 dB in impaired ear may sound loud; this result suggests that the growth of loudness requiring an intensity increase of 60 dB in normal ear is achieved with an intensity increase of 30 dB in impaired ear. This indicates; this is due to abnormality in cochlea such as hypersensitivity of haircells due to damage. Recruitment is a landmark feature of SNHL of cochlear origin. Reverse Recruitment / Decruitment is a hallmark feature of SNHL of Retro Cochlear region; when recruitment is found to be associated with presence of cochlear pathology the recruitment is known as complete recruitment.
When the recruitment is associated with cochlea the concept is known as Partial Recruitment. Low cost and general accessibility Pathophysiologic essence of tone decay is not well known; the actual value of any tone decay procedure in identifying 8 cranial nerve pathology has not been extensively investigated Further reading Carhart, Raymond. "Clinical Determination of Abnormal Auditory Adaptation". A. M. A. archives of otolaryngology, 65, pp. 32–39. Rieber, R. W.. Communication Disorders, p. 66. Springer. ISBN 1475797605 Stach, Brad. Clinical Audiology: An Introduction, p. 304. Cengage Learning. ISBN 0766862887
Hearing, or auditory perception, is the ability to perceive sounds by detecting vibrations, changes in the pressure of the surrounding medium through time, through an organ such as the ear. The academic field concerned with hearing is auditory science. Sound may be heard through liquid, or gaseous matter, it is one of the traditional five senses. In humans and other vertebrates, hearing is performed by the auditory system: mechanical waves, known as vibrations are detected by the ear and transduced into nerve impulses that are perceived by the brain. Like touch, audition requires sensitivity to the movement of molecules in the world outside the organism. Both hearing and touch are types of mechanosensation. There are three main components of the human ear: the outer ear, the middle ear, the inner ear; the outer ear includes the pinna, the visible part of the ear, as well as the ear canal which terminates at the eardrum called the tympanic membrane. The pinna serves to focus sound waves through the ear canal toward the eardrum.
Because of the asymmetrical character of the outer ear of most mammals, sound is filtered differently on its way into the ear depending on what vertical location it is coming from. This gives these animals the ability to localize sound vertically; the eardrum is an airtight membrane, when sound waves arrive there, they cause it to vibrate following the waveform of the sound. The middle ear consists of a small air-filled chamber, located medial to the eardrum. Within this chamber are the three smallest bones in the body, known collectively as the ossicles which include the malleus and stapes, they aid in the transmission of the vibrations from the eardrum into the cochlea. The purpose of the middle ear ossicles is to overcome the impedance mismatch between air waves and cochlear waves, by providing impedance matching. Located in the middle ear are the stapedius muscle and tensor tympani muscle, which protect the hearing mechanism through a stiffening reflex; the stapes transmits sound waves to the inner ear through the oval window, a flexible membrane separating the air-filled middle ear from the fluid-filled inner ear.
The round window, another flexible membrane, allows for the smooth displacement of the inner ear fluid caused by the entering sound waves. The inner ear consists of the cochlea, a spiral-shaped, fluid-filled tube, it is divided lengthwise by the organ of Corti, the main organ of mechanical to neural transduction. Inside the organ of Corti is the basilar membrane, a structure that vibrates when waves from the middle ear propagate through the cochlear fluid – endolymph; the basilar membrane is tonotopic, so that each frequency has a characteristic place of resonance along it. Characteristic frequencies are high at the basal entrance to the cochlea, low at the apex. Basilar membrane motion causes depolarization of the hair cells, specialized auditory receptors located within the organ of Corti. While the hair cells do not produce action potentials themselves, they release neurotransmitter at synapses with the fibers of the auditory nerve, which does produce action potentials. In this way, the patterns of oscillations on the basilar membrane are converted to spatiotemporal patterns of firings which transmit information about the sound to the brainstem.
The sound information from the cochlea travels via the auditory nerve to the cochlear nucleus in the brainstem. From there, the signals are projected to the inferior colliculus in the midbrain tectum; the inferior colliculus integrates auditory input with limited input from other parts of the brain and is involved in subconscious reflexes such as the auditory startle response. The inferior colliculus in turn projects to the medial geniculate nucleus, a part of the thalamus where sound information is relayed to the primary auditory cortex in the temporal lobe. Sound is believed to first become consciously experienced at the primary auditory cortex. Around the primary auditory cortex lies Wernickes area, a cortical area involved in interpreting sounds, necessary to understand spoken words. Disturbances at any of these levels can cause hearing problems if the disturbance is bilateral. In some instances it can lead to auditory hallucinations or more complex difficulties in perceiving sound. Hearing can be measured by behavioral tests using an audiometer.
Electrophysiological tests of hearing can provide accurate measurements of hearing thresholds in unconscious subjects. Such tests include auditory brainstem evoked potentials, otoacoustic emissions and electrocochleography. Technical advances in these tests have allowed hearing screening for infants to become widespread; the hearing structures of many species have defense mechanisms against injury. For example, the muscles of the middle ear in many mammals contract reflexively in reaction to loud sounds which may otherwise injure the hearing ability of the organism. There are several different types of hearing loss: Conductive hearing loss, sensorineural hearing loss and mixed types. Conductive hearing loss Sensorineural hearing loss Mixed hearing lossThere are defined degrees of hearing loss: Mild hearing loss - People with mild hearing loss have difficulties keeping up with conversations in noisy surroundings; the most quiet sounds that people with mild hearing loss can hear with their better ear are between 25 and 40 dB HL.
Moderate hearing loss - People with moderate hearing loss have difficulty keeping up with conversations when they are not using a hearing aid. On average, the most quiet sounds heard by
Medical diagnosis is the process of determining which disease or condition explains a person's symptoms and signs. It is most referred to as diagnosis with the medical context being implicit; the information required for diagnosis is collected from a history and physical examination of the person seeking medical care. One or more diagnostic procedures, such as diagnostic tests, are done during the process. Sometimes posthumous diagnosis is considered a kind of medical diagnosis. Diagnosis is challenging, because many signs and symptoms are nonspecific. For example, redness of the skin, by itself, is a sign of many disorders and thus does not tell the healthcare professional what is wrong, thus differential diagnosis, in which several possible explanations are compared and contrasted, must be performed. This involves the correlation of various pieces of information followed by the recognition and differentiation of patterns; the process is made easy by a sign or symptom, pathognomonic. Diagnosis is a major component of the procedure of a doctor's visit.
From the point of view of statistics, the diagnostic procedure involves classification tests. The first recorded examples of medical diagnosis are found in the writings of Imhotep in ancient Egypt. A Babylonian medical textbook, the Diagnostic Handbook written by Esagil-kin-apli, introduced the use of empiricism and rationality in the diagnosis of an illness or disease. Traditional Chinese Medicine, as described in the Yellow Emperor's Inner Canon or Huangdi Neijing, specified four diagnostic methods: inspection, auscultation-olfaction and palpation. Hippocrates was known to make diagnoses by smelling their sweat. A diagnosis, in the sense of diagnostic procedure, can be regarded as an attempt at classification of an individual's condition into separate and distinct categories that allow medical decisions about treatment and prognosis to be made. Subsequently, a diagnostic opinion is described in terms of a disease or other condition, but in the case of a wrong diagnosis, the individual's actual disease or condition is not the same as the individual's diagnosis.
A diagnostic procedure may be performed by various health care professionals such as a physician, physical therapist, healthcare scientist, dentist, nurse practitioner, or physician assistant. This article uses diagnostician as any of these person categories. A diagnostic procedure does not involve elucidation of the etiology of the diseases or conditions of interest, that is, what caused the disease or condition; such elucidation can be useful to optimize treatment, further specify the prognosis or prevent recurrence of the disease or condition in the future. The initial task is to detect a medical indication to perform a diagnostic procedure. Indications include: Detection of any deviation from what is known to be normal, such as can be described in terms of, for example, physiology, pathology and human homeostasis. Knowledge of what is normal and measuring of the patient's current condition against those norms can assist in determining the patient's particular departure from homeostasis and the degree of departure, which in turn can assist in quantifying the indication for further diagnostic processing.
A complaint expressed by a patient. The fact that a patient has sought a diagnostician can itself be an indication to perform a diagnostic procedure. For example, in a doctor's visit, the physician may start performing a diagnostic procedure by watching the gait of the patient from the waiting room to the doctor's office before she or he has started to present any complaints. During an ongoing diagnostic procedure, there can be an indication to perform another, diagnostic procedure for another concomitant, disease or condition; this may occur as a result of an incidental finding of a sign unrelated to the parameter of interest, such as can occur in comprehensive tests such as radiological studies like magnetic resonance imaging or blood test panels that include blood tests that are not relevant for the ongoing diagnosis. General components which are present in a diagnostic procedure in most of the various available methods include: Complementing the given information with further data gathering, which may include questions of the medical history, physical examination and various diagnostic tests.
A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease. Diagnostic tests can be used to provide prognostic information on people with established disease. Processing of the answers, findings or other results. Consultations with other providers and specialists in the field may be sought. There are a number of methods or techniques that can be used in a diagnostic procedure, including performing a differential diagnosis or following medical algorithms. In reality, a diagnostic procedure may involve components of multiple methods; the method of differential diagnosis is based on finding as many candidate diseases or conditions as possible that can cause the signs or symptoms, followed by a process of elimination or at least of rendering the entries more or less probable by further medical tests and other processing until, aiming to reach the point where only one candidate disease or condit