Diagnostic Usefulness of Computed Tomography Compared to Conventional Chest X-Ray for Chest Trauma Patients

PURPOSE: Early diagnosis and management of therapeutic interventions are very important in chest trauma. Conventional chest X-rays (CXR) and computed tomography (CT) are the diagnostic tools that can be quickly implemented for chest trauma patients in the emergency department. In this study, the usefulness of the CT as a diagnostic measurement was examined by analyzing the ability to detect thoracic injuries in trauma patients who had visited the emergency department and undergone CXR and CT. METHODS: This study involved 84 patients who had visited the emergency department due to chest trauma and who had undergone both CXR and CT during their diagnostic process. The patients' characteristics and early vital signs were examined through a retrospective analysis of their medical records, and the CXR and the CT saved in the Picture Archiving Communication System (PACS) were examined by a radiologist and an emergency physician to verify whether or not a lesion was present. RESULTS: Pneumothoraxes, hemothoraxes, pneumomediastina, pulmonary lacerations, rib fractures, vertebral fractures, chest wall contusions, and subcutaneous emphysema were prevalently found in a statistically meaningful way (p<0.05) on the CT. Even though their statistical significance couldn't be verified, other disorders, including aortic injury, were more prevalently found by CT than by CXR. CONCLUSION: CT implemented for chest trauma patients visiting the emergency department allowed disorders that couldn't be found on CXR to be verified, which helped us to could accurately evaluate patients.

Effects of Gaze Positions on Ocular Vestibular Evoked Myogenic Potentials / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Recent works have demonstrated the existence of ocular vestibular evoked myogenic potentials (OVEMPs), which reflects otolith-ocular reflex. The purpose of this study was to identify an appropriate gaze position to detect OVEMPs produced by air-conducted sound stimulation in healthy subjects. SUBJECTS AND METHOD: Twenty four healthy subjects (35 ears) were included in this study. Surface electromyographic activity was recorded from active electrodes placed inferior to each eye. Stimulation with 500 Hz short tone bursts was used to activate the vestibular end-organs. RESULTS: Sound stimulation evoked negative-positive biphasic responses on both ipsilateral and contralateral eyes, while responses were contralateral eye-dominant. Contralateral eye responses had higher response incidence and larger amplitudes. Altering the direction of gaze generally changed the incidence and size of the inter-peak amplitudes. The higher incidence and larger amplitudes were recorded when the eyes are directed to the superior and ipsilateral side to the sound stimulation. In that gaze position, the amplitude was 5.3 micronV, the first negative peak latency was 10.5 ms and the following positive peak latency was 15.4 ms on the average. CONCLUSION: OVEMPs can be evoked using an air-conducted 500 Hz tone burst and are best recorded contralaterally with a upward gaze towards the source of sound stimulation. Further changes of the test parameters are needed for higher and consistent responses.

Clinical Analysis of the Etiology of Korean Olfactory Disorders / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: This study examined the causes and epidemiologic factors of smell loss in Koreans using the Korean Version of the Sniffin' Sticks Test and compared the results with cases of foreign countries. SUBJECTS AND METHOD: The data of 386 patients who visited clinics complaining of smell loss were retrospectively analyzed with medical charts. RESULTS: Idiopathic, upper respiratory tract infection, trauma, nasal and paranasal sinus disease were the major causes of smell loss in this study. The distribution of gender and age, severity of smell loss, association of smell loss with allergies and nasal polyps were discussed in detail. CONCLUSION: The proportion of each cause observed in this study was different compared with the results of other domestic reports of nasal and paranasal sinus disease, but came out similar to the results of foreign studies.

Tympanometry and CT Measurement of Middle Ear Volumes in Patients with Unilateral Chronic Otitis Media

OBJECTIVES: The goals of the study were to compare the middle ear (ME) volumes from both normal and lesioned ears, and these ME volumes were measured by a digital image processing computed tomography (CT) program in patients with unilateral chronic otitis media, and we wanted to compare the ME volumes of the lesioned ears by comparing the ME volumes obtained by tympanometry with those ME volumes measured by the digital image processing CT program. METHODS: Forty-four patients who had unilateral chronic otitis media (COM) and contralateral normal tympanic membranes (TM) and 100 subjects with normal TMs were included in the study. The normal volumes of the external auditory canal (EAC) were measured in the normal group. The tympanometric ME volumes in the ears with a perforated TM were calculated as the difference of the tympanometric volumes measured from the both ears in patients with unilateral COM. The CT ME volumes were measured by a digital image processing program. RESULTS: The tympanometric volumes of the EACs in the ears with normal TMs were 1.4+/-0.3 mL. There were no significant differences according to gender, age and the side of the face the ear was on. The tympanometric volumes of the EAC in the normal-side ear of the patients with unilateral COM showed no significant differences when compared with those from the normal group. The ME volumes of the intact ears, as measured by CT, showed significantly higher values than those ME volumes of the lesioned ears. The ME volumes of the lesioned ears, as measured by tympanometry, showed a strong, significant linear correlation with those ME volumes calculated by CT; however, the ME volumes of the lesioned ears, as measured by tympanometry (1.5+/-1.4 mL), were significantly larger than those ME volumes measured by CT (1.1+/-0.8 mL). CONCLUSION: Our results show that chronic otitis media causes reduced ME volumes compared to those ME volumes of the contralateral normal ears. Tympanometry can provide a valuable estimation of the ME volumes in chronic ears, although it tends to overestimate the ME volumes, and especially for the ears with a larger ME volume.

Otolith Function Tests in Patient with Meniere's Disease

BACKGROUND AND OBJECTIVES: The aims of this study were to measure otolith function using subjective visual vertical (SVV) test and vestibular evoked myogenic potential (VEMP) test in patients with unilateral Meniere's disease, and to see the relationship of the otolithic impairment with caloric and audiologic results. MATERIALS AND METHODS:Twenty two patients with unilateral Meniere's disease who received treatment and also had been tested for pure tone, caloric, SVV and VEMP tests were enrolled. All the tests were done simultaneously. RESULTS: Five of 22 (23%) patients showed abnormal tilt to the lesion side in SVV test, and 13 of 22 (59%) patients showed abnormal VEMP results on the affected side. There was no correlation between SVV tilts and unilateral weakness (UW) in caloric tests or pure-tone average. There was also no difference of UW in patients with or without VEMP abnormalities. Two patients showed abnormal finding in both SVV & VEMP tests. One patient showed UW (47%) and SVV tilt (3.08degrees) to the lesion side, and the other showed normal UW and SVV tilt (3.22degrees) to the lesion side. CONCLUSION: Our results demonstrate that the otolith system was implicated in 16 out of 22 (73%) patients with Meniere's disease. However, there was no correlation between the abnormal results of the three tests and these findings suggest that impairment of the otolithic function is depending on the extent and/or the localization of Meniere's disease, suggesting vestibular rehabilitation for the specific lesion might be helpful.

Comparison of Air Caloric Test and Vibration-Induced Nystagmus Test in Patients with Unilateral Chronic Otitis Media without Vertigo

BACKGROUND AND OBJECTIVES: The aims of the study were to characterize the vibration-induced nystagmus (VIN) and air caloric test in patients with unilateral chronic otitis media, and to clarify the clinical availability of VIN by comparing the results of VIN test with those of air caloric test. MATERIALS AND METHODS: Nineteen patients with unilateral chronic otitis media who had had no vestibular symptoms in past history were investigated. Pure tone audiometry (PTA), air caloric, VIN and subjective visual vertical (SVV) tests were done and the results were analyzed to estimate the utility for investigating vestibular imbalance. RESULTS: If we consider a patient with abnormal results from two or more tests as a patient with latent vestibular imbalance, because they had no previous vestibular symptoms, 3 patients was considered to have latent asymmetric vestibular function. False positive rate were 32% in air caloric test, 5% in VIN test and 0% in SVV test. CONCLUSION: Our findings show that vestibular imbalance in patients with chronic otitis media should be determined through various tests and vibration-induced nystagmus test can be more useful than air caloric test in estimating the vestibular imbalance.

Follow-up Examination of Vibration-Induced Nystagmus in Patients with Unilateral Vestibular Neuritis

BACKGROUND AND OBJECTIVES: The aim of this study was to verify if vibration-induced nystagmus in patients with vestibular neuritis changed over time and to compare the results of vibration-induced nystagmus (VIN) test to those of caloric test. MATERIALS AND METHOD: We compared VIN results with those of caloric testing in 23 patients (M:F = 11:12, 15~67 years old) with unilateral vestibular neuritis seen at onset and in follow-up for around 2 months. The eye movement recordings were made and the maximum slow-phase eye velocities (SPV) were calculated during vibration. If spontaneous nystagmus was present, it was subtracted from the slow-phase eye velocities of VIN. RESULTS: In acute stage, VIN of which SPV was directed towards the lesioned side was observed in 21 (91%). In follow-up, VIN of which SPV was directed towards the lesioned side was observed in 19 (83%). There was a significant decrease of the SPV of VIN over time. Significant correlations were observed in between canal paresis & SPV of VIN in both acute and follow-up stages. CONCLUSION: Our findings show that VIN test can predict the severity of vestibular asymmetry not only in acute stage but also in follow-up stage. Our results suggest that vibration-induced nystagmus might represent the peripheral vestibular asymmetry in patients with vestibular neuritis.

Changes of Vibration-Induced Nystagmus by Age in Normal Subjects

BACKGROUND AND OBJECTIVES: It has been reported that vibration applied either on the mastoid or on the sternocleidomastoid (SCM) muscles induces nystagmus in normal subjects. The aims of the study were to characterize the direction and velocity of slow-phase eye movement which is induced by vibration in normal subjects and to propose the mechanism of vibration-induced nystagmus (VIN) in normal subjects. MATERIALS AND METHOD: We recorded eye movements during unilateral 100-Hz vibration on the mastoid bone and SCM muscles in 56 normal subjects. The subjects were divided into 4 groups in ages (20s, 30s, 40s, 50~60s). The directions of VIN, the degree of maximal slow-phase eye velocities were analyzed according to age. Positive value means slow-phase velocity (SPV) to the right side. RESULTS: In 20s, vibration on right/left mastoids induced SPV of 1.2+/-2.0degrees/sec, 0+/-2.1degrees/sec and on right/left SCM muscles, 1.1+/-1.9degrees/sec, -1.2+/-2.5degrees/sec. In 30s, vibration on right/left mastoids induced SPV of 3.3+/-3.8degrees/sec, -0.3+/-1.4degrees/sec and on right/left SCM muscles, 2.8+/-4.2degrees/sec, -1.0+/-1.5degrees/sec. In 40s, vibration on right/left mastoids induced SPV of 0+/-1.7degrees/sec, -0.2+/-1.2degrees/sec and on right/left SCM muscles, 0+/-1.8degrees/sec, 0+/-1.0degrees/sec. In 50~60s, vibration on the right/left mastoids induced SPV of -1.3+/-1.3degrees/sec, 1.2+/-1.3degrees/sec and on right/left SCM muscles, -0.6+/-0.9degrees/sec, 0.9 +/-1.5degrees/sec. The directional preponderance of the slow-phase eye movement to the vibrated side was statistically significant in 20s and 30s, however, the preponderance of the slow-phase eye movement changed into the non-vibrated side in 50~60s. CONCLUSION: The proprioceptive input, changing major rotator from the inferior oblique muscle to the sternocleidomastoid muscles might explain the change of the directional preponderance of the slow-phase eye movements in normal subjects according to ages. Although this directional preponderance is not consistent in all age groups, it is still important in discriminating normal responses from abnormal responses which can be induced by vibration.

Vibration-Induced Nystagmus in Patients with Vestibular Disorders

BACKGROUND AND OBJECTIVES: It has been reported that vibration applied either on the mastoid or the sternocleidomastoid (SCM) muscles induces nystagmus in patients after unilateral vestibular neuritis. The aims of the study were to characterize the vibration-induced nystagmus (VIN) in patients with various vestibular disorders and to compare the results of VIN to unilateral weakness in caloric test. MATERIALS AND METHODS:Fifthy-four patients with Meniere's disease, 58 patients with unilateral vestibular neuritis, 170 patients with migraine-associated dizziness, and 78 patients with chronic recurrent vestibulopathy were included. We recorded eye movements during unilateral 100-Hz vibration on the mastoids and SCM muscles. The bithermal caloric test was also performed. Abnormal criteria of VIN were slow-phase slow-phase velocity (SPV) at 4 all different conditions > or = 2degrees/s with the same directions or mean of SPV at vibration on both mastoids or both SCM muscles > or = 5degrees/s with the same directions. RESULTS: In Meniere's disease, 28 of 57 (49.1%) of patients show pathologic VIN, 21 of 57 (36.8%) show pathologic canal paresis. 14 of 57 (24.6%) show abnormalities in both tests, and 35 of 57 (61.4%) show any abnormalities in either test. In unilateral vestibular neuritis, 43 of 58 (77.6%) showed pathologic VIN, 58 of 58 (100%) show canal paresis. In migraine-associated dizziness, 48 of 170 (28.2%) showed pathologic VIN, 58 of 170 (18.8%) show canal paresis. 15 of 170 (8.8%) showed abnormalities in both tests, and 65 of 170 (38.2%) show any abnormalities in either test. In chronic recurrent vestibulopathy, 23 of 78 (29.5%) of patients show pathologic VIN and 17 of 78 (21.8%) show pathologic canal paresis. Seven of 78 (9.0%) showed abnormalities in both tests, and 33 of 78 (42.3%) show any abnormalities in either test. CONCLUSION: VIN test can increase the sensitivity in detecting vestibular imbalance in vestibular disorders when combined with caloric test.

Changes of VEMP Responses by the Strength of SCM Muscles Contraction and Stimulation Intensities / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The aim of this study was to investigate the effect of the strength of SCM muscle contraction and the intensity of the sound stimulation on the VEMP parameters (amplitude, latency and threshold). SUBJECTS AND METHOD: Twenty normal subjects were included. Subjects pushed with their jaw against the hand-held inflated cuff to generate cuff pressures of 20, 40 and 60 mmHg and sequential stimulation intensities were applied. Variances of each parameter were analyzed. RESULTS: There was no significant difference in terms of threshold according to the side and strength of SCM contraction. P1-N1 amplitude demonstrated no significant differences according to the side ; however, the amplitude increased significantly as the cuff pressure and stimulation intensity increased. Interaural amplitude difference ratios showed an increased difference at 20 mmHg when compared to those at 60 mmHg. There was neither a cuff pressure effect, nor stimulation intensity effect when considering the P1 latencies. As for the N1 values, there was no stimulation intensity effect but there was a delayed latency at 20 mmHg when compared to those at 40 or 60 mmHg. Interaural latency difference of N1 latencies did not differ significantly according to the cuff pressure ; however, there was an increased difference at 20 mmHg when compared to those at 40 or 60 mmHg. CONCLUSION: This study shows that VEMP response is influenced by the cuff pressure and stimulation intensity, and we recommend to get each VEMP parameter using this feedback method in the clinical setting.

Clinical Manifestations of Patients with Migraine-associated Vertigo / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The clinical association between migraine and vestibular symptoms has been indicated in many studies and it is believed that migraine-associated vertigo is one of the most common causes of spontaneous recurrent vertigo. SUBJECTS AND METHOD: We investigated the nature of vestibular and migrainous symptoms of 26 patients suffering vertigo associated with migraine and their responses to antimigrainous medications. Neurotologic tests such as oculomotor tests, calorictest, and audiometry were performed between attacks. RESULTS: A marked female predominance was found. The duration of rotational (77%) and/or to-and-fro vertigo (23%) lasted from a few seconds to several hours or, less frequently, even days. We found that patients showed vestibular abnormalities in central and peripheral types. In the symptom-free interval, 31% of the patients showed central oculomotor signs such as delayed saccadic latency and horizontal saccadic pursuit. On the other hand, 15% showed unilateral weakness in the caloric test and 15% showed positive results in the head thrust tests. Overall, 85% of patients experienced resolution or significant reduction of their attacks of vertigo with medication. CONCLUSION: Most patients with migraine-associated vertigo showed normal results on the vestibular tests and responded well to preventive medication. Migraine-associated vertigo caused various clinical manifestations and there should be relevant differential diagnosis for epiodic vertigo.

Otolith Function Tests in Patient with Vestibular Neuritis

BACKGROUND AND OBJECTIVES: Vestibular evoked myogenic potentials (VEMP) test provides a useful method for assessment of saccule function and the functional integrity of the inferior vestibular nerve, and subjective visual vertical (SVV) abnormalities are presumably related to a lesion of the utricle. The aim(s) of this study were to measure otolith function using SVV and VEMP tests, and to define the influence of the otolithic organs in patients suffering from vestibular neuritis. MATERIALS AND METHOD: From September 2005 to January 2006, twelve patients who received treatment in hospital and also had been tested for caloric test, subjective visual vertical (SVV) and vestibular evoked myogenic potential (VEMP) tests with unilateral vestibular neuritis were enrolled. All the tests were done within 8 days after the onset of their symptoms, simultaneously. The SVV was measured in 34 normal subjects as well as in patients. RESULTS: Eight of 12 patients showed abnormal tilt to the lesion side in SVV test, and five of 8 patients showed no VEMP on the affected side. There was no correlation between SVV tilts and unilateral weakness (UW) in caloric tests. Two patients with abnormal UW (54, 82%) showed normal finding in SVV & VEMP tests. One patient with abnormal UW (83%) and SVV tilts (18.04Degree) to the lesion side was normal in VEMP test. Two patients with abnormal UW (28, 37%) and no response in VEMP test were normal in SVV test. CONCLUSION: Our results demonstrate that the incidence of abnormal results were 62.5, 66.7% in VEMP and SVV tests in acute stage of vestibular neuritis, respectively. There was no correlation between the abnormal results of the tests and these findings suggest that impairment of the otolithic function is depending on the extent and/or the localization of vestibular neuritis.

Otolith Function Tests in Patient with Vestibular Neuritis

BACKGROUND AND OBJECTIVES: Vestibular evoked myogenic potentials (VEMP) test provides a useful method for assessment of saccule function and the functional integrity of the inferior vestibular nerve, and subjective visual vertical (SVV) abnormalities are presumably related to a lesion of the utricle. The aim(s) of this study were to measure otolith function using SVV and VEMP tests, and to define the influence of the otolithic organs in patients suffering from vestibular neuritis. MATERIALS AND METHOD: From September 2005 to January 2006, twelve patients who received treatment in hospital and also had been tested for caloric test, subjective visual vertical (SVV) and vestibular evoked myogenic potential (VEMP) tests with unilateral vestibular neuritis were enrolled. All the tests were done within 8 days after the onset of their symptoms, simultaneously. The SVV was measured in 34 normal subjects as well as in patients. RESULTS: Eight of 12 patients showed abnormal tilt to the lesion side in SVV test, and five of 8 patients showed no VEMP on the affected side. There was no correlation between SVV tilts and unilateral weakness (UW) in caloric tests. Two patients with abnormal UW (54, 82%) showed normal finding in SVV & VEMP tests. One patient with abnormal UW (83%) and SVV tilts (18.04Degree) to the lesion side was normal in VEMP test. Two patients with abnormal UW (28, 37%) and no response in VEMP test were normal in SVV test. CONCLUSION: Our results demonstrate that the incidence of abnormal results were 62.5, 66.7% in VEMP and SVV tests in acute stage of vestibular neuritis, respectively. There was no correlation between the abnormal results of the tests and these findings suggest that impairment of the otolithic function is depending on the extent and/or the localization of vestibular neuritis.

Occult Lymph Node Metastasis in Early Oral Tongue Squamous Cell Carcinoma / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The most significant prognosticator of survival for patients with squamous cell carcinoma of the oral tongue has been the association of neck nodal metastasis. However, no consensus exists as to whether an elective neck dissection should be performed in patients with early oral tongue squmous cell carcinoma with a clinically negative neck. SUBJECTS AND METHOD: A retrospective analysis was performed on 54 early oral tongue squamous cell carcinoma patients (T1=26 and T2=28) with clinically negative necks who were treated between 1992 to 2003. All patients had an ipsilateral neck dissection and 29 patients had a contralateral neck dissection. Surgical treatment was followed by postoperative radiotherapy in 20 patients. The follow-up period ranged from 3 to 110 months (mean, 56 months). Data were analyzed using the Kaplan-Meier method, log-rank test, and the chi-square test. RESULTS: Clinically occult, but pathologically positive ipsilateral lymph nodes were found in 26% (14/54) and contralateral lymph nodes in 3% (1/29). Based on the clinical staging of the tumor, 19% (5 of 26) of the cases showed lymph node metastases in T1 tumors, and 36% (10 of 28) in T2. All regional recurrences developed in the ipsilateral necks, there was no cases of contralateral neck recurrence. Patients with no evidence of occult nodal cancer have significantly improved disease-specific free survival rates over patients with any pathologically positive nodes (5 year disease specific survival rate, 90% vs 38%, p< or = 0.05). CONCLUSION: This study showed that ipsilateral elective neck dissection should be performed for early oral tongue cancers. On the other hand, our series suggests that it may not be harmful to observe the contralateral N0 neck in the treatment of early oral tongue cancer.

Interutricular and Intermastoid Distance Measured in the Koreans Using MRI / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The distance between the utricles is important in vestibular tests like the unilateral centrifugation test for examining the utricular function. In this test, the axis of rotation crosses precisely through one utricle, thus only the opposite utricle is stimulated. The interutricular distance needs to be known in order to stimulate one utricle maximally for this test, and it would be better if the distance could be estimated from surface landmarks like intermastoid distance. SUBJECTS AND METHOD: We investigated the correlation between the interutricular distance (IUD) and the intermastoid distance (IMD), measured on magnetic resonance images. Data were collected from 177 subjects (72 men and 105 women), who suffered from dizziness, sensorineural hearing loss and facial nerve disorders. RESULTS: We found that IUDs were 7.33+/-0.42 cm (6.03-8.75 cm) and the maximum difference of IUDs between the subjects was 2.73 cm. There was a significant correlation between IUD and IMD. The IUDs of men (7.57+/-0.38 cm) and women (7.17+/-0.38 cm) showed the similar correlation with those of IMD. The correlation was not different from that published for Caucasian subjects. CONCLUSION: These findings show that there is a significant correlation between IUD and IMD. IMD can be useful for estimating IUD, which enables exact stimulation to be given to the unilateral utricle in the unilateral centrifugation test. Moreover, individual assessment of IUD gives more precise stimulation than using a fixed IUD in the unilateral centrifugation test.

The Effect of Somatosensory Input on Subjective Visual Vertical in Normal Subjects

BACKGROUND AND OBJECTIVES: Aims of the study were to determine if the somatosensory input influences on vertical perception by comparing the results with the head or body tilted (15Degree to the right and to the left, and to examine the influence of tactile sensation in the perception of verticality in head lateral positions. MATERIALS AND METHOD: We tested 34 normal subjects in their ability to set a straight line to the perceived gravitational vertical. Measurements were taken in static conditions, sitting upright, head tilted (15Degree, body tilted (15Degree, and head lateral positions (90Degree on the right/left sides with or without physical support under the head. RESULTS: The normal range of the subjective visual vertical (SVV) was 0.65Degree/-.23Degreein upright position. The normal ranges of SVV in head-tilts 15Degreeto the left/right sides were -0.47Degree/-.76Degreeand 1.88Degree/-.94Degree which were significantly different from those in upright position (E-effect). But the normal ranges of SVV in body-tilts 15Degreeto the left/right were not different from those in upright position. And the normal ranges of SVV in head lateral positions maintained actively and passively were not different each other, but significantly larger than that in upright position (A-effect). CONCLUSION: Our results support that neck somatosensory input plays a part in the perception of verticality. In contrast, tactile sensation of the head had no effect on the settings of a visual line to visual vertical in head lateral positions.

Management of Contralateral N0 Neck in Tonsillar Squamous Cell Carcinomas / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: It is well established that tonsillar squamous cell carcinoma has high probability to be disseminated to the neck. An ipsilateral neck treatment is mandatory during initial treatment stages of II-IV tonsillar carcinomas. However, no consensus exists as to whether an elective contralateral neck management should be performed. SUBJECTS AND METHOD: A retrospective analysis was performed on 43 N1-3 tonsillar cancer patients with contralateral negative necks who were treated between 1992 to 2002. All patients had a contralateral elective neck dissection. Surgical treatment was followed by postoperative radiotherapy in 33 patients. The follow-up period ranged from 2 to 120 months (mean, 38 months). The Kaplan-Meier method and log-rank test were used to calculate the disease-specific survival rates and prognostic significance of contralateral occult lymph node metastasis. RESULTS: Clinically occult, but pathologically positive contralateral lymph nodes were found in 16% (7 of 43). In cases of ipsilateral N (+) neck, contralateral occult lymph node metastases developed in 21% (7 of 33) and there was no incidence of that in the cases of ipsilateral N0 necks. Based on the clinical stages of the tumor, 5% (1 of 22) of the cases metastatically involved ymph nodes in the T2 tumors, 36% (5 of 14) in the T3, and 25% (1 of 4) in the T4. T1 tumors (3 cases) had no pathologically positive lymph nodes (T1+T2 vs T3+T4, p<.05). Patients with no evidence of contralateral nodal cancer had significantly improved disease-specific free survival rates over patients with any pathologically positive nodes (5 year disease specific survival rate, 92% vs 28%, p=<.05). CONCLUSION: The risk of contralateral occult neck involvement in above T3 staged tonsillar squamous cell carcinomas with unilateral metastases was high and patients who presented with contralateral metastatic neck have worse prognosis than those who are staged as N0. Therefore, we advocate a routine bilateral neck dissection in tonsillar squamous cell carcinoma patients with unilateral node metastases.