Motion sickness (MS) can be problematic for many military operations. Some pharmaceutical counter... more Motion sickness (MS) can be problematic for many military operations. Some pharmaceutical countermeasures are effective but can lead to side effects. Non-pharmaceutical countermeasures vary in effectiveness and can require time to be beneficial (e.g., desensitization). Previous research suggests that visual fixation can alleviate MS symptoms. In the current experiment we tested the effectiveness of a user-worn device that provides a visual fixation point that moves with the user. Fourteen subjects viewed the interior of a rotating optokinetic drum (60°/s) through a visor that displayed either a clear view of the scene (control) or the scene with a fixation point (experimental). After 5 minutes of viewing, symptoms were assessed using (1) the Simulator Sickness Questionnaire that yields four scores (total, nausea, oculomotor, and disorientation) and (2) a 0 to 10 MS overall scale. Viewing the fixation point resulted in significantly lower scores for all measures. Control condition sc...
Research during the past two decades has demonstrated an important role of the vestibular system ... more Research during the past two decades has demonstrated an important role of the vestibular system in topographical orientation and memory and the network of neural structures associated with them. Almost all of the supporting data have come from animal or human clinical studies, however. The purpose of the present study was to investigate the link between vestibular function and topographical memory in normal elderly humans. Twenty-five participants aged 70 to 85 years who scored from mildly impaired to normal on the Montreal Cognitive Assessment (MoCA) received three topographical memory tests: the Camden Topographical Recognition Memory Test (CTMRT), a computerized topographical mental rotation test (TMRT), and a virtual pond maze (VPM). They also received six vestibular or oculomotor tests: optokinetic nystagmus (OKN), visual pursuit (VP), actively generated vestibulo-ocular reflex (VOR), the sensory orientation test (SOT) for posture, and two measures of rotational memory (error in degrees, or RM • , and correct directional recognition, or RM→). The only significant bivariate correlations were among the three vestibular measures primarily assessing horizontal canal function (VOR, RM • , and RM→). A multiple regression analysis showed significant relationships between vestibular and demographic predictors and both the TMRT (R = 0.78) and VPM (R = 0.66) measures. The significant relationship between the vestibular and topographical memory measures supports the theory that vestibular loss may contribute to topographical memory impairment in the elderly.
Motion sickness and complaints of dizziness caused by provocative vestibular stimulating environm... more Motion sickness and complaints of dizziness caused by provocative vestibular stimulating environments have been a widespread problem, affecting a significant portion of the world's population to varying degrees. The research objective was to determine if symptoms of motion sickness and associated nystagmus could be mitigated using an eye worn device which displayed an artificial horizon with a vertex point in the center for visual fixation, while experiencing vestibular stimulation. Assessment methods included an eye tracker, to measure velocity and duration of nystagmus, while patients underwent vestibular stimulation. This was followed by SSQ scoring to evaluate motion sickness symptoms. Users were tested with and without a visual display of specific symbology, while undergoing vestibular stimulation. Results demonstrated the associated nystagmus was significantly reduced in velocity and duration. With caloric stimulation testing, the duration of nystagmus was greater than 60seconds in the group without the visual display but decreased to 3.3seconds when using the displayed symbology and instructing the user to focus on the vertex point between the artificial horizon and centered vertical line. Eye speed of nystagmus was diminished from 13.6degrees/second, to 0.4degrees/second while using the visual display. Similar finding were noted with Barany Chair stimulation. The duration of nystagmus, which persisted for 25.8seconds without the visual display, was decreased to 7.4seconds when using display and focusing on the vertex point. The eye speed of nystagmus was also decreased from 26.3 degrees/second to 5.7degrees/second when using the visual display with vertex fixation. Objective SSQ scores were compared with and without visualization of the displayed symbology. When symbology was visualized, nausea, oculomotor symptoms, and disorientation were less apparent. In conclusion, using an eye worn device which displays specific user orientation symbology can mitigate the symptoms of motion sickness and related nystagmus when experiencing vestibular stimulation.
International Journal of Otolaryngology and Head & Neck Surgery, 2013
Electrocochleography (ECoG) has been an important tool in the diagnosis of Meniere's disease or e... more Electrocochleography (ECoG) has been an important tool in the diagnosis of Meniere's disease or endolymphatic hydrops. There are two methods employed, transtympanic and extratympanic. Many have regarded the results of these methods as being equally reliable. The purpose of this study is to determine any differences in sensitivity between the two methods. In this study patients with known endolymphatic hydrops or Meniere's disease underwent ECoG testing with both the extratympanic method and the transtympanic method on the same day in the same ear. The results show a significant difference between the two methods, with the transtympanic wave values being smaller and therefore more sensitive than the extratympanic method. In addition, transtympanic ECoG resulted in better waveform morphology and better correlation with the audiometric findings in endolymphatic hydrops and Meniere's disease. The results emphasize the superior role of transtympanic ECoG over extratympanic ECoG as a valuable component in the confirmation of Meniere's disease or endolymphatic hydrops along with history and audiometric findings characteristic of the disease. Implications of the study promote the use of transtympanic ECoG rather than extratympanic ECoG in patients with symptoms suggestive of Meniere's disease or endolymphatic hydrops.
Ten patients with plexiform neurofibroma of the head and neck were observed at M.D. Anderson Hosp... more Ten patients with plexiform neurofibroma of the head and neck were observed at M.D. Anderson Hospital between 1956 and 1978. The clinical presentation and the long-term follow-up of the most interesting cases are presented. This is a chronic disease that causes cosmetic and functional deformity because of the size or the position of the tumor, or both. No patient exhibited malignant transformation. Because all of the disease cannot be removed, the surgical procedures should not be radical but should be designed to relieve symptoms or improve cosmesis.
Interest in electrocochleography has increased in recent years because of the discovery of an ele... more Interest in electrocochleography has increased in recent years because of the discovery of an elevated summating potential to action potential amplitude ratio (SP/AP ratio) in patients with endolymphatic hydrops caused by Menière's disease or perilymph fistula. It was the purpose of this investigation to determine whether the intraoperative SP/AP ratio will decrease after vestibular nerve section in patients with intractable Meniere's disease. Fourteen patients with medically intractable classic Menière's disease underwent retrosigmoid vestibular nerve section. Intraoperative transtympanic electrocochleography was performed with alternating click stimuli presented at 95 dB HL. In all patients the SP/AP ratio was recorded before the skin incision ("baseline" condition) and after the dura was closed ("closing" condition). Statistical analysis was applied to the recorded data. In 11 (79%) patients, the SP/AP ratio was found to be elevated above 0.30 in the baseline state. In 13 (93%) patients, the SP/AP ratio decreased more than 25% after the nerve was sectioned. These results were highly statistically significant (p < 0.001). We conclude that the SP/AP ratio does decrease in patients with Menière's disease after undergoing retrosigmoid vestibular nerve section and offer a possible explanation.
Otolaryngology-head and Neck Surgery - OTOLARYNGOL HEAD NECK SURG, 2002
Objective: We sought to compare the findings of 3 different hearing screening methods in school-a... more Objective: We sought to compare the findings of 3 different hearing screening methods in school-aged children. Study Design and Setting: Prospective testing of second- and third-grade students in their schools was carried out. Methods: Three hundred children (599 ears) were screened by using 3 test modalities, pure-tone audiometry, distortion product otoacoustic emissions (DPOAE), and tympanometry. Results: All of the tests were normal in 532 ears (89%), and all were abnormal in 12 ears (2%). Tympanometry yielded the most abnormalities (8.3%), and pure-tone testing demonstrated the fewest (3.3%), with a positive rate of 6.3% for DPOAE testing. False-positive rates were 1.2%, 4.2%, and 6.4% for pure tones, DPOAE, and tympanometry, respectively, when normal results on pure-tones or DPOAE were taken to represent true hearing. Conclusion/Significance: We continue to recommend pure-tone testing as an effective screening method, with follow-up by using otoacoustic emissions in those who f...
With the continued concern over the possible transmission of viral infections through homologous ... more With the continued concern over the possible transmission of viral infections through homologous middle ear implants, there is increasing pressure to develop a truly biocompatible alloplastic middle ear prosthesis. The polymaleinate ionomer, which has been used in dentistry as a filling and luting material for more than 15 years, has recently been used to construct total and partial ossicular replacement
Motion sickness (MS) can be problematic for many military operations. Some pharmaceutical counter... more Motion sickness (MS) can be problematic for many military operations. Some pharmaceutical countermeasures are effective but can lead to side effects. Non-pharmaceutical countermeasures vary in effectiveness and can require time to be beneficial (e.g., desensitization). Previous research suggests that visual fixation can alleviate MS symptoms. In the current experiment we tested the effectiveness of a user-worn device that provides a visual fixation point that moves with the user. Fourteen subjects viewed the interior of a rotating optokinetic drum (60°/s) through a visor that displayed either a clear view of the scene (control) or the scene with a fixation point (experimental). After 5 minutes of viewing, symptoms were assessed using (1) the Simulator Sickness Questionnaire that yields four scores (total, nausea, oculomotor, and disorientation) and (2) a 0 to 10 MS overall scale. Viewing the fixation point resulted in significantly lower scores for all measures. Control condition sc...
Research during the past two decades has demonstrated an important role of the vestibular system ... more Research during the past two decades has demonstrated an important role of the vestibular system in topographical orientation and memory and the network of neural structures associated with them. Almost all of the supporting data have come from animal or human clinical studies, however. The purpose of the present study was to investigate the link between vestibular function and topographical memory in normal elderly humans. Twenty-five participants aged 70 to 85 years who scored from mildly impaired to normal on the Montreal Cognitive Assessment (MoCA) received three topographical memory tests: the Camden Topographical Recognition Memory Test (CTMRT), a computerized topographical mental rotation test (TMRT), and a virtual pond maze (VPM). They also received six vestibular or oculomotor tests: optokinetic nystagmus (OKN), visual pursuit (VP), actively generated vestibulo-ocular reflex (VOR), the sensory orientation test (SOT) for posture, and two measures of rotational memory (error in degrees, or RM • , and correct directional recognition, or RM→). The only significant bivariate correlations were among the three vestibular measures primarily assessing horizontal canal function (VOR, RM • , and RM→). A multiple regression analysis showed significant relationships between vestibular and demographic predictors and both the TMRT (R = 0.78) and VPM (R = 0.66) measures. The significant relationship between the vestibular and topographical memory measures supports the theory that vestibular loss may contribute to topographical memory impairment in the elderly.
Motion sickness and complaints of dizziness caused by provocative vestibular stimulating environm... more Motion sickness and complaints of dizziness caused by provocative vestibular stimulating environments have been a widespread problem, affecting a significant portion of the world's population to varying degrees. The research objective was to determine if symptoms of motion sickness and associated nystagmus could be mitigated using an eye worn device which displayed an artificial horizon with a vertex point in the center for visual fixation, while experiencing vestibular stimulation. Assessment methods included an eye tracker, to measure velocity and duration of nystagmus, while patients underwent vestibular stimulation. This was followed by SSQ scoring to evaluate motion sickness symptoms. Users were tested with and without a visual display of specific symbology, while undergoing vestibular stimulation. Results demonstrated the associated nystagmus was significantly reduced in velocity and duration. With caloric stimulation testing, the duration of nystagmus was greater than 60seconds in the group without the visual display but decreased to 3.3seconds when using the displayed symbology and instructing the user to focus on the vertex point between the artificial horizon and centered vertical line. Eye speed of nystagmus was diminished from 13.6degrees/second, to 0.4degrees/second while using the visual display. Similar finding were noted with Barany Chair stimulation. The duration of nystagmus, which persisted for 25.8seconds without the visual display, was decreased to 7.4seconds when using display and focusing on the vertex point. The eye speed of nystagmus was also decreased from 26.3 degrees/second to 5.7degrees/second when using the visual display with vertex fixation. Objective SSQ scores were compared with and without visualization of the displayed symbology. When symbology was visualized, nausea, oculomotor symptoms, and disorientation were less apparent. In conclusion, using an eye worn device which displays specific user orientation symbology can mitigate the symptoms of motion sickness and related nystagmus when experiencing vestibular stimulation.
International Journal of Otolaryngology and Head & Neck Surgery, 2013
Electrocochleography (ECoG) has been an important tool in the diagnosis of Meniere's disease or e... more Electrocochleography (ECoG) has been an important tool in the diagnosis of Meniere's disease or endolymphatic hydrops. There are two methods employed, transtympanic and extratympanic. Many have regarded the results of these methods as being equally reliable. The purpose of this study is to determine any differences in sensitivity between the two methods. In this study patients with known endolymphatic hydrops or Meniere's disease underwent ECoG testing with both the extratympanic method and the transtympanic method on the same day in the same ear. The results show a significant difference between the two methods, with the transtympanic wave values being smaller and therefore more sensitive than the extratympanic method. In addition, transtympanic ECoG resulted in better waveform morphology and better correlation with the audiometric findings in endolymphatic hydrops and Meniere's disease. The results emphasize the superior role of transtympanic ECoG over extratympanic ECoG as a valuable component in the confirmation of Meniere's disease or endolymphatic hydrops along with history and audiometric findings characteristic of the disease. Implications of the study promote the use of transtympanic ECoG rather than extratympanic ECoG in patients with symptoms suggestive of Meniere's disease or endolymphatic hydrops.
Ten patients with plexiform neurofibroma of the head and neck were observed at M.D. Anderson Hosp... more Ten patients with plexiform neurofibroma of the head and neck were observed at M.D. Anderson Hospital between 1956 and 1978. The clinical presentation and the long-term follow-up of the most interesting cases are presented. This is a chronic disease that causes cosmetic and functional deformity because of the size or the position of the tumor, or both. No patient exhibited malignant transformation. Because all of the disease cannot be removed, the surgical procedures should not be radical but should be designed to relieve symptoms or improve cosmesis.
Interest in electrocochleography has increased in recent years because of the discovery of an ele... more Interest in electrocochleography has increased in recent years because of the discovery of an elevated summating potential to action potential amplitude ratio (SP/AP ratio) in patients with endolymphatic hydrops caused by Menière's disease or perilymph fistula. It was the purpose of this investigation to determine whether the intraoperative SP/AP ratio will decrease after vestibular nerve section in patients with intractable Meniere's disease. Fourteen patients with medically intractable classic Menière's disease underwent retrosigmoid vestibular nerve section. Intraoperative transtympanic electrocochleography was performed with alternating click stimuli presented at 95 dB HL. In all patients the SP/AP ratio was recorded before the skin incision ("baseline" condition) and after the dura was closed ("closing" condition). Statistical analysis was applied to the recorded data. In 11 (79%) patients, the SP/AP ratio was found to be elevated above 0.30 in the baseline state. In 13 (93%) patients, the SP/AP ratio decreased more than 25% after the nerve was sectioned. These results were highly statistically significant (p < 0.001). We conclude that the SP/AP ratio does decrease in patients with Menière's disease after undergoing retrosigmoid vestibular nerve section and offer a possible explanation.
Otolaryngology-head and Neck Surgery - OTOLARYNGOL HEAD NECK SURG, 2002
Objective: We sought to compare the findings of 3 different hearing screening methods in school-a... more Objective: We sought to compare the findings of 3 different hearing screening methods in school-aged children. Study Design and Setting: Prospective testing of second- and third-grade students in their schools was carried out. Methods: Three hundred children (599 ears) were screened by using 3 test modalities, pure-tone audiometry, distortion product otoacoustic emissions (DPOAE), and tympanometry. Results: All of the tests were normal in 532 ears (89%), and all were abnormal in 12 ears (2%). Tympanometry yielded the most abnormalities (8.3%), and pure-tone testing demonstrated the fewest (3.3%), with a positive rate of 6.3% for DPOAE testing. False-positive rates were 1.2%, 4.2%, and 6.4% for pure tones, DPOAE, and tympanometry, respectively, when normal results on pure-tones or DPOAE were taken to represent true hearing. Conclusion/Significance: We continue to recommend pure-tone testing as an effective screening method, with follow-up by using otoacoustic emissions in those who f...
With the continued concern over the possible transmission of viral infections through homologous ... more With the continued concern over the possible transmission of viral infections through homologous middle ear implants, there is increasing pressure to develop a truly biocompatible alloplastic middle ear prosthesis. The polymaleinate ionomer, which has been used in dentistry as a filling and luting material for more than 15 years, has recently been used to construct total and partial ossicular replacement
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Papers by WESLEY Krueger