Fully endoscopic interlaminar and transforaminal lumbar discectomy: clinical results of 857 surgically treated patients.

Minimally invasive surgical techniques are becoming increasingly common in spinal surgery in an attempt to decrease tissue trauma during surgery, which in turn decreases post-operative pain and opioid use. The aim of this study was to investigate the clinical outcomes of a large group of patients with lumbar disc disease who underwent full endoscopic surgery. 857 patients who underwent fully endoscopic lumbar discectomy were investigated retrospectively. General demographics were evaluated in terms of mean operating time, mean length of hospital stay, mean time to return to work, complications and recurrences. Clinical outcomes were evaluated using visual analogue scale (VAS) for low back and leg pain, and Oswestry Disability Index (ODI) for functional assessment. The mean follow-up time was 36 months. The operation time ranged from 20 to 65 minutes (39 min on average), and there was no measurable intraoperative blood loss. Patients were mobilised on average 3.5 hours after the surgery. The length of hospital stay after the operation was 12-24 hours (18 hours on average). During postoperative follow-up, 19 patients required revision surgery due to recurrence (2.2%). There was one case of nerve root injury in which the patient recovered well following physical therapy, and 11 cases of paresthesia that gradually improved following 2-6 weeks of rehabilitation and treatment with pregabalin. All types of lumbar disc herniations are accessible via the full-endoscopic technique. Full-endoscopic discectomy, as a minimally invasive procedure, has the technical advantages of less paraspinal muscle dissection, less tissue trauma, less risk of spinal instability, and minimal blood loss.

Exogenous Cushing syndrome due to misuse of potent topical steroid.

We report an infant with exogenous Cushing syndrome after being treated for 2 months with a potent topical corticosteroid via the mother's application of topical clobetasol for diaper rash without a prescription. We emphasize that potent topical steroids should be used with great caution, especially when used under occlusion (e.g., diaper area) and that parents should be warned about potential side effects of these medications, particularly when used in infants.

The comparison of edema and ecchymosis after piezoelectric and conventional osteotomy in rhinoplasty.

The basic aim of our study is to compare the results of the conventional and piezoelectric osteotomy in rhinoplasty by complete subperiosteal degloving of nasal bone to minimize soft-tissue injury. The study was designed as a prospective, double-blind, randomized, and controlled study. Setting is a tertiary referral hospital in Turkey. Ninety patients who underwent primary open rhinoplasty with osteotomy, performed by either the conventional instruments or the piezoelectric device. The complete subperiosteal degloving of the entire nasal bone was done up to the nasal maxillary sulcus, medial canthus, and nasion in all patients, independent of the type of osteotomy device used. Patients subsequently underwent median-oblique and lateral osteotomy, either with an ultrasonic device or a conventional 2-mm guarded, straight osteotome. The postoperative edema and ecchymosis were evaluated by another surgeon who was blinded to the osteotomy procedure on postoperative days 2 and 7. The edema scores were significantly increased on the second day compared with the seventh day in both groups 1 and 2. However, there was no significant difference between groups. The ecchymosis scores were slightly higher in postoperative day 2, compared with day 7, in both groups 1 and 2, but statistically not significant. This study showed that the main reason edema and ecchymosis are seen post-rhinoplasty is related to soft-tissue injury during osteotomy.

Extended lateral thoracic fasciocutaneous biosynthetic flap for reconstruction of full-thickness partial external ear defects: an experimental study.

External ear reconstruction is a controversial topic in reconstructive plastic surgery. Here, we prepared a pedicled biosynthetic flap for full-thickness, partial ear defects in rabbits. We operated on six adult female New Zealand rabbits weighing 3-4 kg. The dimensions of the lateral thoracic fasciocutaneous flap were 7 × 6 cm. The flap was elevated based on one of the bilaterally located internal thoracic arteries, which were dissected proximally. The pedicled flap was folded in two, and polypropylene mesh was sandwiched in the middle. The flap was adapted to a defect of 3.5 × 3 cm in diameter. In fact, the defect was created before elevation of the flap. Rabbits were followed up for 4 weeks, at the end of which they were killed and their ears were evaluated histopathologically. The survival rate of the rabbits was 100 %. All pedicled biosynthetic flaps were viable, but one showed partial (20 %) necrosis (1/6) and one was partially detached (1/6). Macroscopic (color, thickness, texture) and histological (polymorphonuclear leukocyte invasion in the skin, subcutaneous tissue, and at the junction between the polypropylene mesh and the flap) features of the flap were compared to the ipsilateral ear. A new technique was developed for partial external ear reconstruction with sufficient inner skeletal support and outer skin lining. Level of evidence Level NA.

Effects of ozone (O3) therapy on cisplatin-induced ototoxicity in rats.

The aim of this study is to investigate the effect of rectal ozone and intratympanic ozone therapy on cisplatin-induced ototoxicity in rats. Eighteen female Wistar albino rats were included in our study. External auditory canal and tympanic membrane examinations were normal in all rats. The rats were randomly divided into three groups. Initially, all the rats were tested with distortion product otoacoustic emissions (DPOAE), and emissions were measured normally. All rats were injected with 5-mg/kg/day cisplatin for 3 days intraperitoneally. Ototoxicy had developed in all rats, as confirmed with DPOAE after 1 week. Rectal and intratympanic ozone therapy group was Group 1. No treatment was administered for the rats in Group 2 as the control group. The rats in Group 3 were treated with rectal ozone. All the rats were tested with DPOAE under general anesthesia, and all were sacrificed for pathological examination 1 week after ozone administration. Their cochleas were removed. The outer hair cell damage and stria vascularis damage were examined. In the statistical analysis conducted, a statistically significant difference between Group 1 and Group 2 was observed in all frequencies according to the DPOAE test. In addition, between Group 2 and Group 3, a statistically significant difference was observed in the DPOAE test. However, a statistically significant difference was not observed between Group 1 and Group 3 according to the DPOAE test. According to histopathological scoring, the outer hair cell damage score was statistically significantly high in Group 2 compared with Group 1. In addition, the outer hair cell damage score was also statistically significantly high in Group 2 compared with Group 3. Outer hair cell damage scores were low in Group 1 and Group 3, but there was no statistically significant difference between these groups. There was no statistically significant difference between the groups in terms of stria vascularis damage score examinations. Systemic ozone gas therapy is effective in the treatment of cell damage in cisplatin-induced ototoxicity. The intratympanic administration of ozone gas does not have any additional advantage over the rectal administration.

Indirect laryngoscopic assessment for the diagnosis of difficult intubation in patients undergoing microlaryngeal surgery.

BACKGROUND: The aim of this study is to investigate the feasibility of using indirect laryngoscopy for the diagnosis of difficult intubations in patients who are undergoing microlaryngeal surgery. METHODS: In the pre-anesthetic examination the thyromental distance, sternomental distance, interincisor distance, neck circumference, modified Mallampati scores, and Wilson risk scores were measured. An otolaryngologist conducted an indirect laryngoscopic assessment. Direct laryngoscopic profiles were classified according to their Cormack-Lehane scores. RESULTS: Forty patients underwent microlaryngeal surgery. Their mean ages, neck circumferences, Cormack-Lehane scores of the patients who had intubation difficulties were statistically significantly higher than those who did not have intubation difficulties (p < 0.05). The significant differences between the indirect laryngoscopic assessment distributions of patients who either had or did not have intubation difficulty were assessed (p < 0.05). CONCLUSIONS: Indirect laryngoscopic assessment is a simple and valuable technique that can be used for the diagnosis of difficult intubation in patients who are undergoing microlaryngeal surgery.

The analysis of the maxillary sinus volumes and the nasal septal deviation in patients with antrochoanal polyps.

The aim of this study was to evaluate the relationship between the maxillary sinus volumes and the nasal septal deviation angles in patients with antrochoanal polyps (ACP). 76 patients who underwent ACP surgery were included in the study. Of those 36 patients who had multislice computed tomography (MSCT) were evaluated to calculate maxillary sinus volume. The records of paranasal MSCT of 36 healthy people without any paranasal sinus diseases or surgery constituted age- and gender-matched healthy controls. Maxillary sinüs volumes and septal deviation angles were calculated using the paranasal MSCT volume-rendering technique. Thirty-six patients in the ACP group were compared with 36 polyp side-matched healthy people. The mean age was 16.6 ± 6.7 years in both groups. Statistically, the mean value of the maxillary sinus volume was significantly higher in the ACP group compared with the ACP side-matched control group (15.1 ± 4.6 versus 12.0 ± 3.5 mm(3)) (p = 0.002). Furthermore, the mean value of the maxillary sinus volume in the non-polyp side (14.2 ± 4.7 mm(3)) was statistically higher in the ACP group compared with the side-matched control group volume (11.9 ± 3.8 mm(3)) (p = 0.024). In addition, Fifty-three of 76 ACP patients had septal deviation. While the septal deviation was on the same side with the ACP in 17 patients, it was on the opposite side in 36 patients. In conclusion, the maxillary sinus volumes increased in ACP patients compared with the healthy control group. Many patients had nasal septal deviation on the opposite side of the ACP.

Metastatic follicular thyroid carcinoma masquerading as olfactory neuroblastoma: with skull-base, cranium, paranasal sinus, lung, and diffuse bone metastases.

Skull-base metastasis is rarely reported in thyroid carcinoma. We are presenting an unusual interesting case mimicking metastatic renal cell carcinoma with intense clear cell morphology, the thyroid origin of which was detected via positron emission tomography/computerized tomography scan proposed by the oncology council, while we were monitoring the subject with the initial diagnosis of paranasal sinus tumor. A mass was detected in the left nasal cavity in the endoscopic examination of the 68-year-old female patient referred by the ophthalmology clinic with the preliminary diagnosis of retro-orbital tumor upon being admitted with proptosis. A soft tissue lesion at a size of 68 × 39 × 53 mm located intracranially was detected by the brain computerized tomography. The biopsy taken and the immunohistochemical results were not satisfactory. Intense fluorodeoxyglucose involvement was observed in both lobes of the thyroid gland at positron emission tomography/computerized tomography taken with the recommendation of the council. Moreover, hypermetabolic nodules were seen in both lung parenchyma areas, whereas intense hypermetabolic lytic lesions were observed in the skeletal system. Thyroglobulin and thyroid transcription factor 1 stains displayed a strong staining on paraffin block. On the basis of these characteristics, the case was regarded as compatible metastatic follicular thyroid carcinoma, with skull-base, cranial, retro-orbital, paranasal sinus, lung, and bone metastases. This case showed us that multidisciplinary work and assessment of the oncology council play a highly critical role in making the diagnosis and guiding the treatment.

The effects of air pollutants on nasal functions of outdoor runners.

Nowadays road running is becoming more and more popular in our country. Road running is mostly done under improper conditions. The aim of this study was to investigate the effects of running on nasal response combined with the effects of air pollutants. Twenty road runners were enrolled in the study. All subjects were male and between 20 and 41 years of age. They ran for 60 min on the right side of an avenue in the center of the city. It is in a residential area but has heavy traffic. One week later they were invited to run for 60 min through a running course away from traffic that is located outside the city center. Nasal resistances were measured by active anterior rhinomanometry. Nasal transport time was also measured by saccharin transport method. There was a reduction in nasal resistance, which was statistically significant in city center runners but was not statistically significant in those running outside of the city center after the exercise. Although nasal transport times were statistically shorter in both groups, there were no differences between two groups. Nowadays, everyone is advised to do sports. Due to increase in the number of breaths, the depth of breathing, and the reduction in nasal resistance in outdoor runners during exercise, harmful air pollution particles can easily reach the lower respiratory tract. Exercise is important for our health, but it should be noted that the environment in which we run is as important as doing sports for our health, especially in outdoor runners.

Morphometric analysis of the maxillary sinus in patients with nasal septum deviation.

The aim of this study was to evaluate the relationship between nasal septum deviation, which is common in the general population, and maxillary sinus volume. A retrospective assessment was made for 96 patients with nasal septum deviation without coexisting sinonasal morbidity and compared to 60 healthy individuals. A three-dimensional reconstruction of computed tomography images was used to assess a total of 312 maxillary sinus volumes. Septal deviation angles and volumes were also measured to standardize and determine the severity of the septal deviations. Septal deviations were right-sided in 36.5% of the cases (n = 35) and left-sided in 63.5% (n = 61). Deviation angles varied between 5° and 24.4°, with a mean value of 12.9 ± 5.0. The mean value for the deviation volume was 4.6 ± 1.5 cm(3) (range 1.7-9.4). The right and left maxillary sinus volumes were 11.8 ± 4.7 cm(3) and 11.5 ± 4.4 cm(3), respectively, in control group. Statistically significant discrepancy was observed between the ipsilateral and contralateral maxillary sinus volumes, in regard to the side of the septal deviation in study group. Maxillary sinus volumes were found to be significantly smaller on the ipsilateral side of septal deviation compared with the contralateral side.

Tympanometric changes and eustachian tube function in patients with hypothyroidism.

OBJECTIVE: The aim of this study was to investigate the tympanometric changes and eustachian tube function (ETF) in patients with hypothyroidism. METHODS: Automatic ETF tests were performed and tympanometric measurements were evaluated to assess ETF in 40 patients diagnosed with hypothyroidism and a 40-patient euthyroid control group. Levothyroxine sodium tablet treatment was started in patients with hypothyroidism. After achieving a euthyroid state in these patients, the tympanometric measurements and automatic ETF tests were repeated. RESULTS: When the patient groups (hypothyroid and control) were compared in terms of ETF, a statistically significant ET dysfunction was observed in the hypothyroid patient group (P < 0.01).When hypothyroid patients were evaluated in terms of ETF before and after treatment, whereas 61.3% of cases had ET function before treatment, this ratio increased to 78.8% after treatment. Furthermore, according to pressure and compliance measurements, statistically significant increases were found in the after treatment measurements (P < 0.05). CONCLUSIONS: As a result of this study, we have come to the opinion that hypothyroidism can change tympanometric measurements and also cause ET dysfunction. However, more comprehensive and detailed studies researching the effects of hypothyroidism on tympanometric measurements are needed.

The impact of pharyngeal repair time and suture frequency on the development of pharyngocutaneous fistula after total laryngectomy.

OBJECTIVE: Pharyngocutaneous fistula (PCF) is the most common postoperative complication after total laryngectomy. The aim of this study was to determine the relationship between PCF with pharyngeal repair time and the number of mucosal sutures. METHODS: The medical records of 47 patients who underwent total laryngectomy were assessed prospectively. The pharyngeal repair time and the number of horizontal, vertical, and cricopharyngeal muscle sutures were recorded. We observed the occurrence of PCF in 14 patients (29.8%). The mean time for pharyngeal repair in the PCF group was 22 minutes 59 seconds ± 5 minutes, and the mean number of vertical, horizontal, and cricopharyngeal muscle sutures was 8.57 ± 2.6, 11.14 ± 2.1, and 8.45 ± 1.9, respectively. The mean time for pharyngeal repair in the non-PCF group was 22 minutes 21 seconds ± 5 minutes, and the mean number of vertical, horizontal, and cricopharyngeal muscle sutures was 9.54 ± 2.6, 10.84 ± 2.3, and 7.36 ± 2.7, respectively. The differences in the pharyngeal repair time and the number of vertical, horizontal, and cricopharyngeal sutures between the 2 groups were not statistically significant (P > 0.05). Besides, there was no statistically significant difference between the mean suture counts per centimeter in horizontal plane (1.46 ± 0.35) and vertical plane (0.98 ± 0.25) in the PCF group and the mean suture counts per centimeter in horizontal plane (1.42 ± 0.37) and vertical plane (1.13 ± 0.3) in the non-PCF group (P > 0.05). CONCLUSIONS: There was no relation between PCF development with pharyngeal repair time, mucosal suture count, and suture frequency after total laryngectomy.

[An efficacy comparison of betahistin, trimetazidine and ginkgo biloba extract in patients with tinnitus]. / Tinnituslu hastalarda trimetazidin, betahistin ve ginkgo biloba ekstresi etkinliginin karsilastirilmasi

OBJECTIVES: This study aims to investigate the efficacy of trimetazidine, betahistine and ginkgo biloba extract in the treatment of tinnitus. PATIENTS AND METHODS: Complete clinical data of 90 patients (48 males, 42 females; mean age 52.3±15.1 years; range 20 to 61 years) who received betahistine, trimetazidine and ginkgo biloba extract for three months were retrospectively analyzed. The patients were divided into three groups including 30 in each group according to treatments received. Pre-treatment and post-treatment scores of tinnitus disability questionnaire were compared statistically. RESULTS: There was no statistically significant difference between pre-treatment scores of tinnitus disability questionnaire among all three groups (p>0.05), while there was a statistically significant difference among the groups following treatment (p=0.019, p<0.05). After a-three-month treatment, a decrease of 19.7±15.5 units in trimetazidine group, 12.2±12.7 units in betahistine group, and 3.80±5.9 units in ginkgo biloba extract group were found to be statistically significant, compared to the mean pretreatment tinnitus disability questionnaire scores (p=0.002, p<0.01). CONCLUSION: Our study results suggest that trimetazidine, betahistin and ginkgo biloba extract reduce tinnitus symptoms. However, symptomatic relief can be mostly achieved with trimetazidine treatment.

Enhanced nerve growth factor expression by mast cells does not differ significantly between idiopathic and allergic rhinitis.

BACKGROUND: The role of neurotrophins in allergic rhinitis (AR) has been well studied, but it has not been evaluated in idiopathic rhinitis (IR). OBJECTIVE: We aimed to evaluate the nasal ß-nerve growth factor (ß-NGF) expressions of mast cells in patients with AR and IR. METHODS: Seventeen patients with house dust mites-induced persistent moderate/severe allergic rhinitis (mean age: 29.7 ± 11.96), 14 patients with idiopathic rhinitis (mean age, 29.3 ± 10.62), and 16 healthy controls (29.9 ± 11.57) were included in the study. Nasal biopsy specimens were taken from the posterior part of the inferior turbinate from all of the study subjects. Nasal ß-nerve growth factor and its receptors, pan-neurotrophin receptor p75, and tyrosine kinase A (trkA) were assessed with an immunofluorescence assay. Mast cells were determined by both an immunofluorescence assay and immunohistochemistry as tryptase-positive cells. RESULTS: The ß-NGF, trkA, and p75 receptor counts were significantly higher in AR and IR patients than in the control group (P < .001, for each), but they were not different between AR and IR patients. Similarly, the ratio of ß-NGF+ mast cells/total mast cells and the ratio of ß-NGF+ mast cells/total ß-NGF+ cells in AR and IR patients was found to be elevated when compared with the control group (P < .001, P < .001, P < .001, and P = .046, respectively); furthermore, the 2 ratios were not statistically different between the 2 patient groups. CONCLUSION: The increase in ß-NGF-expressing mast cells does not differ between idiopathic and allergic rhinitis. Therefore, we propose that mast cells do play a role in the pathogenesis of IR as important as in that of AR.

Co-occurrence of diaphragmatic and serratus anterior muscle hydatidosis: an unusual localization.

BACKGROUND: With hydatid cyst, the skeletal muscles and diaphragm are rarely affected, and hepatic and pulmonary hydatid cysts are far more common. We report a case with an unusual localization of diaphragmatic and serratus muscle anterior hydatidosis that occurred simultaneously. CASE REPORT: A 37-year-old developmentally disabled woman presented to the Emergency Department (ED) of Harran University with tachycardia, tachypnea, and dyspnea. On pulmonary auscultation, breath sounds were decreased on the right side. A chest X-ray study revealed a radiopaque right hemithorax with a mediastinal shift and tracheal displacement. Thoracic computed tomography scan revealed a hydatid cyst in the serratus muscle anterior and cystic vesicles in the pleural cavity. The patient underwent chest drainage. During drainage, daughter vesicles within the pus were detected macroscopically. An elective thoracotomy was performed after hemodynamic stabilization of the patient. Postoperative chest X-ray study demonstrated that the lungs had re-expanded. The patient had no postoperative complications and was discharged with relief of all symptoms. CONCLUSION: Hydatid cyst should be considered, especially in endemic regions, in the differential diagnosis in the presence of a rare localization or unexpected clinical presentation. Surgical intervention is the appropriate approach for the treatment of hydatid cyst when there is concomitant intrathoracic involvement.

Atypical presentation of primary giant nasal septal mucopyocele.

Mucoceles are expansile, encapsulated, benign cystic lesions with the potential for adjacent bony remodeling and resorption. Previous nasal surgery, recurrent infections, allergies, and facial traumas are all possible causes of mucoceles involving mainly paranasal sinuses. When the mucocele is infected, it is referred to as mucopyocele. Nasal septal mucoceles seen in only very seldom cases might develop from pneumatized and infected nasal septa. In the current article, we present an interesting primary giant septal mucopyocele that destroys all paranasal cells as a tumoral lesion. The perpendicular plate of ethmoidal bone, vomer, and bilateral anterior and posterior ethmoidal cells were destroyed by mucopyocele. The nasal cavity was totally obstructed by lesions on both sides. On the left side, the lesion also eroded the left lateral nasal wall causing external swelling at the medial canthal region. This is the first case of a giant septal mucopyocele of its kind in the literature. Although nasal septal mucocele is very rare, it should be considered in differential diagnosis of intranasal masses.

The oxidant/antioxidant status and cell death mode in oral squamous cell carcinoma.

OBJECTIVE: Oxidative stress and imbalance in the oxidant/antioxidant system have a critical role in carcinogenesis by affecting necrosis and apoptosis. The aim of this study is to evaluate the oxidant/antioxidant status and cell death modes in patients with oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: Twenty-nine patients with OSCC and 29 control subjects were included in the study. The levels of malondialdehyde (MDA), advanced oxidation protein products (AOPP) and ferric reducing antioxidant power (FRAP) were determined in plasma samples of all subjects. The necrotic and apoptotic cell death modes were evaluated with M65 ELISA and M30 ELISA, respectively. RESULTS: MDA and AOPP values as oxidative stress markers were higher in patients with OSCC than in the control group. FRAP values evaluating plasma antioxidant status increased in OSCC patients. M65 and M30 levels indicating necrosis and apoptosis were significantly higher in OSCC patients compared to controls. There were significant correlations between MDA, AOPP and FRAP; M65 and M30 values. CONCLUSIONS: The elevated levels of oxidative stress markers together with the increase of antioxidant capacity and the presence of a strong correlation between MDA, AOPP and FRAP suggest an activation of antioxidant defense against accentuated oxidative stress determined in OSCC. Enhanced oxidation of lipids and proteins may cause decomposition of cell membranes with subsequent leakage of cytoskeletal cytokeratins as CK18 and caspase-cleaved CK18 (evaluated as M65 and M30, respectively) in the circulation, suggesting that both cell death modes are affected in OSCC.

Application of multifrequency bioelectrical impedance analysis method for the detection of dehydration status in professional divers.

BACKGROUND AND OBJECTIVE: The level of dehydration has been known to be a predisposing factor for the development of decompression sickness in divers. The aim of this study was to determine the level of dehydration in divers who dove with heliox and to determine whether the source of this dehydration was intracellular and/or extracellular by means of multifrequency bioelectrical impedance analysis (MF-BIA). MATERIAL AND METHODS: Eleven male professional divers were enrolled in the study. In order to determine the level of dehydration, MF-BIA was carried out (at 5, 50, and 100 kHz) and capillary hematocrit (Hct) was measured two times: one before diving and the other after leaving the pressure room. RESULTS: When prediving and postdiving parameters were compared, significant increases in the resistance at 5 kHz (P<0.001), 50 kHz, (P<0.001), and 100 kHz (P<0.01) and Hct (P<0.01) were observed after the diving. Similarly, a statistically significant fluid shift was found: total body water, -1.30 L (P<0.001), extracellular water, -0.85 L (P<0.001); and intracellular water, -0.45 L (P=0.011). CONCLUSIONS: Our results showed that mild dehydration occurred both in the intracellular and extracellular compartments in divers after deep diving. This study also indicates that MF-BIA could be a reliable new method for determining the dehydration status in divers.

Effects of Hyperbaric Nitrogen Narcosis on Cognitive Performance in Recreational air SCUBA Divers: An Auditory Event-related Brain Potentials Study.

BACKGROUND: The narcotic effect of hyperbaric nitrogen is most pronounced in air-breathing divers because it impairs diver's cognitive and behavioral performance, and limits the depth of dive profiles. We aimed to investigate the cognitive effects of simulated (500 kPa) air environments in recreational SCUBA divers, revealed by auditory event-related potentials (AERPs). METHODS: A total of 18 healthy volunteer recreational air SCUBA divers participated in the study. AERPs were recorded in pre-dive, deep-dive, and post-dive sessions. RESULTS: False-positive score variables were found with significantly higher differences and longer reaction times of hits during deep-dive and post-dive than pre-dive sessions. Also, P3 amplitudes were significantly reduced and peak latencies were prolonged during both deep-dive and post-dive compared with pre-dive sessions. CONCLUSION: We observed that nitrogen narcosis at 500 kPa pressure in the dry hyperbaric chamber has a mild-to-moderate negative effect on the cognitive performance of recreational air SCUBA divers, which threatened the safety of diving. Although relatively decreased, this effect also continued in the post-dive sessions. These negative effects are especially important for divers engaged in open-sea diving. Our results show crucial implications for the kinds of control measures that can help to prevent nitrogen narcosis and diving accidents at depths up to 40 msw.

Decompression illness medically reported by hyperbaric treatment facilities: cluster analysis of 1929 cases.

INTRODUCTION: The term decompression illness (DCI) describes maladies resulting from inadequate decompression, but there is little consensus concerning clinically useful DCI subclasses. Our aim was to explore an objective DCI classification using multivariate statistics to assess naturally associated clusters of DCI manifestations. We also evaluated their mapping onto other DCI classifications and investigated the association with therapeutic outcome. METHODS: We defined the optimal number of clusters using "two-step" cluster analysis and Bayesian information criterion with confirmation by hierarchical clustering with squared Euclidian distances and Ward's method. The data were 1929 DCI cases reported by hyperbaric chambers to the Divers Alert Network (DAN America) from 1999-2003. RESULTS: Four robust and highly significant clusters of DCI manifestations were demonstrated containing 300, 741, 333, and 555 patients. Each cluster had characteristic manifestations. Cluster 1 was effectively pain only. For Cluster 2, characteristic manifestations included numbness, paresthesia, and decreased skin sensitivity; for Cluster 3, malaise, paralysis, muscular weakness, and bladder-bowel dysfunction; and for Cluster 4, hearing loss, localized skin swelling, tinnitus, skin rash and mottling, confusion, dyspnea/chokes, muscular problems, vision problems, altered consciousness, headache, vertigo, nausea, fatigue, dizziness, and abnormal sensations. DISCUSSION: Internal reliability was confirmed by arbitrarily dividing the dataset into two parts and repeating the analysis. The clusters mapped poorly onto traditional DCI categories (AGE, Type I DCS, Type II DCS), but more specifically onto the Perceived Severity Index (PSI). All three classification methods (DCI, Cluster, PSI) predicted complete relief of manifestations equally well. We conclude that cluster analysis is an objective method for classifying DCI manifestations independent of clinical judgment.