Mach bands, a visual phenomenon resulting from lateral inhibitory impulsess in the retina, are recognized aslucent or dense lines at the borders of different radiographic densities. A number of clinical situations have been described in which Mach bands may cause difficulty in radiographic diagnosis. Photodensitometric measurement of the film can differentiate the true change in film density from the Mach band which is an optical illusion. Authors present several examples of photodensitometric tracings of Mach bands, with the brief review of themechanism of their production.
Diagnosis ; Optical Illusions ; Retina

No abstract available.
Codon ; Hallucinations ; Illusions

The issue of cold damage is one of the major topics of orthodox medicine in East Asia. From the historical view of point, most of the medical practitioners have turned The Theory of Cold Damage to account as their grounds for justifying their own argument. However, it is rare to find a book related to The Theory of Cold Damage in Korea's traditional medicine. Therefore, people have perceived the research status of cold damage is unsatisfactory. This problem could be analyzed by dividing it into a medicinal herb problems and theory problem. First, the medicinal herbs needed for the prescription based on The Theory of Cold Damage don't grow in the Korean Peninsula. Accordingly, there were a lot of restrictions on the free use of these prescriptions. Nevertheless, Chinese medicinal herbs were essential to even the use of the prescriptions besides The Theory of Cold Damage. Accordingly, such aspects do little explain the point that there were few medicine books about The Theory of Cold Damage in Korea. On the other hand, it is hard to exclude the guess that the medical practitioners in the period of the Joseon Dynasty might have presented a theoretically different opinion about cold damage. This study did intensive research on this. As a result of examining the medical practitioners in the latter period of the Joseon Dynasty perceived 'the cold damage to positive and negative meridians' as the case where a patient got attacked by cold as a pathogenic factor in a state of the kidney deficiency. They presented the verdict that kidney deficiency was mostly incurred by sexual relations, and the cold damage to positive and negative meridians broke out when a patient got attacked by cold as a pathogenic factor after having sex. it is an original standpoint shedding light on the relationship between cold damage and the kidney deficiency. The medical practitioners in the latter period of the Joseon Dynasty used Donguibogam as a major text for study on cold damage. In other words, Donguibogam includes the well-organized theory of Yeoksu school who regarded the comparison between internal damage and external damage as important. The medical practitioners in the latter period of the Joseon Dynasty managed to form the theory of the cold damage to positive and negative meridians by deepening the relationship between internal damage and external damage, which was highlighted in Donguibogam. The medical practitioners in the Joseon Dynasty didn't show a big interest in the literature itself, or the so-called The Theory of Cold Damage, which was mainly due to not only the realistic problem of the lack of medicinal herbs needed for applying the prescription to cold damage but also the difference between their positions on cold damage. Therefore, the idea of insufficient research on The Theory of Cold Damage is no more than a kind of optical illusion. On the contrary, we may assume that the medical practitioners in the Joseon Dynasty understood and developed The Theory of Cold Damage in their own way.
Asian Continental Ancestry Group ; Cold Temperature ; Far East ; Hand ; Humans ; Kidney ; Korea ; Light ; Medicine, Traditional ; Meridians ; Optical Illusions ; Plants, Medicinal ; Prescriptions

Total auricular reconstruction with autogenous tissue remains one of the greatest technical challenges for reconstructive plastic surgeons because of the ear's complex morphology with delicately convoluted cartilages and very thin skin. In a successfully created ear, a natural three-dimensional illusion visualized from the patient's profile, frontal, and posterior views is crucial. Accordingly ear framework should have adequate lateral aspect as well as suitable frontal aspect even before being lifted to this purpose. For this goal, rib cartilage should be harvested from three-dimensionally adequate area. It is the most essential point in framework fabrication that the baseblock should have semi-cup curvature via multiple parallel cuts made on its medial surface. Between January 1999 and May 2003, we performed 29 cases of total ear reconstruction with autogenous rib cartilage graft using this scoring technique and obtained satisfactory results, which showed more natural appearance visualized from the patient's profile, frontal, and posterior views.
Cartilage ; Ear* ; Illusions ; Ribs ; Skin ; Transplants

PURPOSE: The aim of the present study was to evaluate the different features of such instruments and how they cause ocular fatigability. METHODS: Under the same settings and circumstances, 75 participants were asked to read the novel, "You without me?" in different formats including paper book, E-book (biscuit(R), Interpark Inc., LG INNOTECK LTD, Korea) and LCD reader (iPad(R), Apple Inc., United States). For every 10 minutes of reading, 10 minutes of rest was provided. After finishing the novel, the participants were asked to complete a questionnaire, and the data obtained were statistically analyzed using univariate analysis. RESULTS: Compared to paper book readers (1.93), LCD readers (2.40) complained of insufficient lubrication in the eye (p = 0.038), and experience more letter-floating illusions (1.92) than did paper book readers (1.49) (p = 0.043). Moreover, compared to the other formats including the E-book (20%) and paper book (8%), LCD readers (72%) experienced more significant glare symptoms (n = 23) and could read at a faster rate than the other groups of readers (n = 26). CONCLUSIONS: In the present study, the I-Pad caused ocular fatigability more easily than the other formats examined. No statistical significance of ocular discomfort or fatigability was observed among the different format groups. Further investigation with a greater number of age-controlled participants should be conducted prior to designing a study to determine the best format for reading.
Dry Eye Syndromes ; Eye ; Glare ; Illusions ; Lubrication ; Multimedia ; Surveys and Questionnaires

PURPOSE: We hypothesized that the central dislocation of the femoral head does generally not occur in transverse acetabular fractures, although it does usually occur in both column fractures. MATERIALS AND METHODS: Fifty-two transverse and both column acetabular fracture cases were evaluated retrospectively. The distances between (a) the sciatic notch on the fracture side and the vertical axis of the pelvis (VA line) and (b) the contralateral intact sciatic notch and the VA line were measured. The a/b ratio corresponded to the superior iliac segment displacement or rotation. The ratio of the distance between the fracture side femoral head and the VA line (c) and the distance between the contralateral intact femoral head and the VA line (d) corresponded to the femoral head displacement. The width of ischium (e) on fractured side and (f) contralateral side were measured. The e/f ratio increment reflected ischiadic fragment mobility. RESULTS: The median value of femoral head displacement (c/d) of the transverse fracture group (n=25) was 1.02 (1.000-1.07). Ischiadic fragment rotation (e/f ratio) of the transverse fracture group was 1.000. The median value of femoral head displacement (c/d) of the both column fractures (n=27) was 0.78 (0.64-0.85). Ischiadic fragment rotation (e/f ratio) of the both-column group was 1.15 (1.06-1.23). The differences between groups according to measurements were statistically significant. CONCLUSION: In contrary to Letournel description, our findings showed no medialization of femoral head in transverse acetabular fractures in general. This might be an illusion resulting from external rotation of the superior iliac segment.
Acetabulum* ; Dislocations* ; Head* ; Hip Dislocation ; Illusions ; Ischium ; Pelvis ; Retrospective Studies

PURPOSE: We hypothesized that the central dislocation of the femoral head does generally not occur in transverse acetabular fractures, although it does usually occur in both column fractures. MATERIALS AND METHODS: Fifty-two transverse and both column acetabular fracture cases were evaluated retrospectively. The distances between (a) the sciatic notch on the fracture side and the vertical axis of the pelvis (VA line) and (b) the contralateral intact sciatic notch and the VA line were measured. The a/b ratio corresponded to the superior iliac segment displacement or rotation. The ratio of the distance between the fracture side femoral head and the VA line (c) and the distance between the contralateral intact femoral head and the VA line (d) corresponded to the femoral head displacement. The width of ischium (e) on fractured side and (f) contralateral side were measured. The e/f ratio increment reflected ischiadic fragment mobility. RESULTS: The median value of femoral head displacement (c/d) of the transverse fracture group (n=25) was 1.02 (1.000-1.07). Ischiadic fragment rotation (e/f ratio) of the transverse fracture group was 1.000. The median value of femoral head displacement (c/d) of the both column fractures (n=27) was 0.78 (0.64-0.85). Ischiadic fragment rotation (e/f ratio) of the both-column group was 1.15 (1.06-1.23). The differences between groups according to measurements were statistically significant. CONCLUSION: In contrary to Letournel description, our findings showed no medialization of femoral head in transverse acetabular fractures in general. This might be an illusion resulting from external rotation of the superior iliac segment.
Acetabulum* ; Dislocations* ; Head* ; Hip Dislocation ; Illusions ; Ischium ; Pelvis ; Retrospective Studies

OBJECTIVES: The course of Alzheimer's disease is often complicated by psychiatric symptoms including depression, delusion and hallucination. And these psychiatric symptoms may be due to neuropathological changes of the disease itself. This study examined whether psychiatric symptoms in Alzheimer's disease are associated with cerebral perfusion using single photon emission computed tomography (SPECT). METHODS: Supratentorial transaxial perfusion measurements were obtained in frontal, anterior temporal, posterior temporoparietal and occipital cortical areas in both hemispheres, in a baseline population of 29 mild to moderately impaired AD patients. We interviewed all the patients and their primary caregivers to assess their current and past psychiatric functioning. To compare the SPECT findings, all the patients were divided into two groups by presence of depression, delusion, hallucination and illusion, of which symptoms were explored separately. RESULTS: The patients with hallucination had hypoperfusion of both the posterior temporoparietal and the occipital regions of interest, compared with scans of the patients without hallucination. And in other symptom profiles, there was no difference in SPECT findings between the patients with symptoms and without symptoms. CONCLUSION: Psychotic patients with Alzheimer's disease had a pattern of cerebral perfusion deficits, which is different from that of nonpsychotic patients. This finding suggests that specific patterns of cerebral dysfunction probably be related to the specific psychiatric symptoms in Alzheimer's disease.
Alzheimer Disease* ; Caregivers ; Delusions ; Depression ; Hallucinations ; Humans ; Illusions ; Perfusion ; Tomography, Emission-Computed, Single-Photon*

We describe a patient who suffered an infarct of the right medial temporal lobe, and developed visual illusions for body images, referred to as Alice in wonderland syndrome (AIWS). Although, these phenomena are usually seen in settings of migraine with aura or epilepsy, an association with strokes has not previously been described. The occurrence of AIWS in our patient, following an infarct of the right medial temporal lobe, provides support for this symptom having a biological and anatomical substrate.
Alice in Wonderland Syndrome* ; Body Image ; Epilepsy ; Humans ; Illusions ; Migraine with Aura ; Stroke ; Temporal Lobe*

BACKGROUND AND OBJECTIVES: Dizziness is an illusion of environmental movement due to various causes. It is difficult to confirm the diagnosis of dizziness according to history and physical examination in restricted situation such as emergency room. The aim of this study is to find another clue for diagnosis in patients of dizziness who visited emergency room. SUBJECTS AND METHOD: Author retrospectively reviewed the charts of 1,060 patients of dizziness who visited emergency room at Chonnam University Hospital from July 2004 to June 2005 and accumulated the various information such as final diagnosis, clinical feature, physical examination, present illness and past history etc. RESULTS: Average age of patients was 57. The most frequently consulted department for evaluation of dizziness was the department of otolaryngology, head and neck surgery (> 29.8%). Benign paroxysmal positional vertigo (BPPV) was the most frequent final diagnosis (14.4%) in all patients. But, cerebrovascular disease was the more frequent cause for dizziness in male and old age group. Whirling type dizziness was frequent in BPPV (36.8%) and spontaneous nystagmus was detected frequently in peripheral type vertigo such as vestibular neuritis (65.1%). Average age of central vertigo patients was 61.4 and other vertigo patients was 55. Patients of central vertigo visited the emergency room more frequently in the months of Dec, Jan, Feb and patient of other vertigo visited more frequently in June, July, Aug. CONCLUSION: Various specialized departments should be involved in effective and exact diagnosis of dizziness. The organized questionnaire in addition to prevalence, incidence and characteristics of dizziness may be used in finding another clue for diagnosis and managing dizzy patients helpfully.
Dizziness ; Emergencies ; Head ; Humans ; Illusions ; Incidence ; Male ; Neck ; Otolaryngology ; Physical Examination ; Prevalence ; Surveys and Questionnaires ; Retrospective Studies ; Vertigo ; Vestibular Neuronitis