Essential components of the directed physical examination include a neurological evaluation emphasizing the cranial nerves and orbital contents (to direct attention to lesions of the skull base) as well as a general evaluation of the ears, upper respiratory tract, and head and neck. Although much can be gained by evaluating the nose using anterior rhinoscopy, nasal endoscopy allows a more thorough assessment. With this procedure, the rhinologist can often directly visualize the olfactory neuroepithelium and establish whether airflow access to the epithelium is blocked. In the nasal examination, the nasal mucosa is evaluated for color, surface texture, swelling, inflammation, exudate, ulceration, epithelial metaplasia, erosion, and atrophy. Discovery of purulent rhinorrhea, especially its site of origin, is considered significant; if it is present throughout the nasal cavity, rhinitis is suggested. If rhinorrhea is present in the middle meatus, maxillary or anterior ethmoid sinusitis is possible, whereas if the frontal recess is involved, frontal sinusitis is implicated. Finally, if rhinorrhea originates from the superior meatus or sphenoethmoidal recess, posterior ethmoid or sphenoid sinusitis is likely. The presence of polyps, masses, adhesions of the turbinates to the septum, and marked septal deviations all have the potential to decrease airflow to the olfactory epithelium. Allergy is suggested if the mucous membrane is pale, usually as a result of edema within the lamina propria. Chronic or acute exposure to environmental or industrial pollutants is suggested by metaplasia within the epithelium as well as by swelling, inflammation, exudate, erosion, or ulceration. Atrophy of the lamina propria is suggested by unusual spaciousness, dryness, and crusting, as seen in atrophic rhinitis or rhinitis medicamentosa.
Quantitative testing of olfactory function is essential to (1) establish the validity of a patient's complaint, (2) characterize the specific nature of the problem, (3) reliably monitor changes in function over time, including those resulting from medical interventions or treatments, (4) detect malingering, and (5) establish compensation for permanent disability. It should be noted that some patients who present with complaints of anosmia or hyposmia actually have normal function relative to their peers. Others can be unaware of their deficits. For example, approximately 90 percent of patients with idiopathic Parkinson's disease have a demonstrable olfactory loss, yet less than 15 percent are aware of the problem until they are tested objectively.
Historically, a popular means of assessing the ability to smell has been to ask a patient to sniff a few small vials containing odorants such as coffee or cinnamon and then report whether or not an odor is perceived. Unfortunately, this procedure is akin to testing vision by shining an intense light into the eye and asking whether or not it can be seen. This problem is not corrected by asking the patient to attempt to identify an odor, since, without cues, even normal subjects have difficulty in identifying some odors. Although most olfactory disorders can be detected by administering a wide variety of nominally distinct olfactory tests, including tests of odor detection, discrimination, identification, and memory, interpretation of the findings of such tests must be done conservatively. All such tests are influenced by damage to the olfactory membrane, making it dangerous to assume, in any given case, that poor performance on a specific type of test (e.g., odor memory) has anything to do with damage to the neural circuits underlying the name of the test (e.g., odor memory circuits). The
fact that the reliability (and hence sensitivity) of a number of such tests is low or unknown adds further difficulty to attempts to establish differential function.
Since assessment of olfactory function often has both medical and legal consequences, accuracy in olfactory testing is essential. Anosmia or hyposmia is a common consequence of head injury and is frequently the only residual neurological impairment of a fall or motor vehicle accident. In the United States, disability compensation is provided under the 1963 amendment to the Workman's Compensation Law when a diminution of future earning power is apparent, and the Veterans Administration awards a 10 percent whole body disability for total anosmia. The Guides to the Evaluation of Permanent Impairment published by the American Medical Association provide another authoritative basis for disability compensation. y However, this document equates total anosmia and total ageusia (a condition that exists rarely, if ever) with a 3 percent impairment of the whole person, a figure that is far below the amount given in most legal settlements for anosmia alone and that many view as insufficient. In Great Britain, disability benefits for anosmia resulting from an injury are available under the National Insurance Act as well under private accident insurance policies. Occupation must be taken into account in disability issues because loss or decreased smell function is quite a different matter for persons in some occupations (e.g., chefs, plumbers, wine tasters, municipal gas workers) than in others (e.g., sanitation workers).
Five practical clinical quantitative tests of olfactory function of known reliability are now commercially available. The most widely used of these tests is the University of Pennsylvania Smell Identification Test (UPSIT), also known as the Smell Identification Test (Sensonics, Inc., Haddonfield, NJ). y , y The UPSIT, which can be self-administered in 10 to 15 minutes by most patients in the waiting room and scored in less than a minute by nonmedical personnel, consists of four booklets containing 10 odorants apiece. The stimuli are embedded in 10- to 50-pm diameter microencapsulated crystals located on "scratch and sniff" strips near the bottom of each page. Above each strip is a multiple choice question with four response alternatives. The patient is required to choose an answer, even if none seems appropriate or no odor is perceived (i.e., the test is forced-choice). This helps to encourage the patient to carefully sample each stimulus and provides a means of detecting malingering; since chance performance is 10 out of 40, very low scores reflect avoidance, and hence recognition, of the correct answer. Norms based on the administration of this test to nearly 4000 people are provided, and an individual's percentile rank is established relative to persons of the same age and gender. y This test makes it possible to classify an individual's function, on an absolute basis, into one of six categories: normosmia, mild microsmia, moderate microsmia, severe microsmia, anosmia, and probable malingering. The reliability of this test is high (test-retest Pearson rs >0.90).
The four other commercially available olfactory tests are the three-item forced-choice microencapsulated Pocket Smell Test (which is only a brief screening test), the 12-item Cross-Cultural Smell Identification Test (CC-SIT), y the five-odorant T&T olfactometer threshold test, y and a squeeze bottle odor threshold test kit. y With the exception of the Pocket Smell Test, the test-retest reliability coefficients of these tests are around 0.70. Norms that take into account both age and gender are available only for the UPSIT and CC-SIT, although the small number of items in the latter test allows neither differentation between degrees of olfactory loss nor a means for determining malingering.
Although most cases of olfactory dysfunction are bilateral, in some instances unilateral testing is needed. To accurately assess olfaction unilaterally, the naris contralateral to the tested side should be occluded to prevent or minimize crossing of inhaled or exhaled air at the rear of the nasopharynx to the opposite side (so-called retronasal stimulation). An easy way of doing this is to seal the contralateral naris using a piece of Microfoam tape (3M Corporation, Minneapolis, MN) cut to fit its borders. The patient is instructed to sniff the stimulus normally and to exhale through the mouth.
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