Surgical options for metastatic spine tumors: WFNS spine committee recommendations.

Surgical treatments for metastatic spine tumors have evolved tremendously over the last decade. Improvements in immunotherapies and other medical treatments have led to longer life expectancy in cancer patients. This, in turn, has led to an increase in the incidence of metastatic spine tumors. Spine metastases remain the most common type of spine tumor. In this study, we systematically reviewed all available literature on metastatic spine tumors and spinal instability within the last decade. We also performed further systematic reviews on cervical metastatic tumors, thoracolumbar metastatic tumors, and minimally invasive surgery in metastatic spine tumors. Lastly, the results from the systematic reviews were presented to an expert panel at the World Federation of Neurosurgical Societies (WFNS) meeting, and their consensus was also presented.

Protective Effect of Thymosin ß4 against Abdominal Aortic Ischemia-Reperfusion-Induced Acute Lung Injury in Rats.

Background and objectives: Ischemia-reperfusion (IR) caused by infrarenal abdominal aorta cross-clamping is an important factor in the development of ischemia-reperfusion injury in various distant organs. Materials and Methods: We investigated potential antioxidant/anti-inflammatory effects of thymosin beta 4 (Tß4) in a rat model of abdominal aortic surgery-induced IR. Tß4 (10 mg/kg, intravenous (i.v.)) was administered to rats with IR (90-min ischemia, 180-min reperfusion) at two different periods. One group received Tß4 1 h before ischemia, and the other received 15 min before the reperfusion period. Results: Results were compared to control and non-Tß4-treated rats with IR. Serum, bronchoalveolar lavage fluid and lung tissue levels of oxidant parameters were higher, while antioxidant levels were lower in the IR group compared to control. IR also increased inflammatory cytokine levels. Tß4 reverted these parameters in both Tß4-treated groups compared to the untreated IR group. Conclusions: Since there is no statistical difference between the prescribed results of both Tß4-treated groups, our study demonstrates that Tß4 reduced lung oxidative stress and inflammation following IR and prevented lung tissue injury regardless of timing of administration.

Remote myocardial injury: the protective role of fluoxetine.

Aortic cross-clamping-induced ischemia-reperfusion (IR) is an important factor in the development of postoperative acute cardiac injury following abdominal aortic surgery. We investigated the possible anti-oxidant/anti-inflammatory effects of fluoxetine (FLX), which is used widely as a preoperative anxiolytic on cardiac injury induced by IR of the infrarenal abdominal aorta. FLX was administered to IR-performed (60 min of ischemia and 120 min of reperfusion) rats for 3 days, once daily at 20 mg/kg i.p. dosage. Results were compared to control and non-FLX-treated IR-performed rats. Serum creatine kinase (CK) and CK-MB levels, lipid hydroperoxide, thiobarbituric acid reactive substances, and pro-oxidant/anti-oxidant balance levels in the IR group were significantly higher whereas superoxide dismutase activity, glutathione, and ferric reducing/anti-oxidant power levels were lower than for the control. IR also increased myeloperoxidase activity, tumor necrosis factor-α, interleukin-1ß, and interleukin-6 and decreased interleukin-10 levels. FLX decreased CK, CK-MB, lipid hydroperoxide, thiobarbituric acid reactive substances, and pro-oxidant/anti-oxidant balance levels while increasing superoxide dismutase activity, glutathione, and ferric reducing/anti-oxidant power levels. FLX also decreased myeloperoxidase activity, tumor necrosis factor-α, interleukin-1ß, and interleukin-6 levels and increased interleukin-10 levels compared to IR. FLX attenuated the morphological changes associated with cardiac injury. Our study clearly demonstrates that FLX confers protection against aortic IR-induced cardiac injury, tissue leucocyte infiltration, and cellular integrity via its anti-oxidant/anti-inflammatory effects.

Sacropelvic fixation in adult spinal deformity (ASD); a very high rate of mechanical failure.

BACKGROUND: Sacropelvic fixation (SPF) is an integral part of ASD surgery. Literature suggests that combination of S1 and iliac screws may be associated with lowest rate of complications. AIM: To analyze the rate and potential factors of mechanical failure associated with SPF in adult spinal deformity surgery. MATERIALS AND METHODS: Of 504 patients enrolled in a prospective multicentric database, 239 were treated conservatively and 265 were treated surgically. Forty-five of those who had sacroiliac fixations and with >6 months (or to failure) f/up constitute the population. Type of iliac fixation was S2 alar/iliac (S2AI) screws in 20 (44.4%) and iliac screws with lateral connectors (IwL) in 25 (55.6%). Diagnoses were degenerative in 20, failed back in 11 and other in 14. Average instrumentation length was 11.6 ± 4.0 levels. Cases with failure were compared to those without using Fisher's Exact and Mann-Whitney U tests. RESULTS: A total of 16 implant related complications were identified (35.6%). Failures were identified on an average of 224.1 days (8-709) following index surgery. Failure rate of S2AI screws was 35 vs. 12% for IwL screws (p > 0.05). All broken screws were associated with S2AI technique with polyaxial screws. Comparison of failed cases to others revealed that failed cases had inadequate restoration of Lumbar Lordosis but this was not statistically insignificant. Only age was a significantly different, patient with failure being older. DISCUSSION: Pelvic fixation is still associated with a very high rate of mechanical failure. Major risk factors appear to be age and type of fixation. Although could not be shown to be statistically significant, failure to restore the optimal sagittal balance may be a contributing factor as well. So in conclusion, in cases with suboptimal sagittal plane correction, S2AI with polyaxial screws seem to have higher risk of short-term acute failure compared to IwL.

Intracranial repair of posttraumatic cerebrospinal fluid rhinorrhea associated with recurrent meningitis.

OBJECTIVE: The purposes of this study are to assess the efficacy of our intracranial surgery and evaluate the association between failure after first surgical repair and the risk factors that have been applied on a group of 13 patients affected by posttraumatic cerebrospinal fluid rhinorrhea associated with recurrent meningitis. METHODS: We retrospectively collected data on 13 patients referred to our institution. All patients had history of head trauma and experienced 2 or more episodes of meningitis. RESULTS: Three of the 13 patients had craniectomy defect due to previous trauma and surgery, 9 patients had linear fracture, and 1 patient had no apparent fracture line on preoperative radiologic evaluation. Ten of the 13 patients had identified frontal bone fracture involving the frontal sinus during surgery. Dural tear was identified intradurally and was repaired using a fascia lata graft with or without fibrin glue. Fibrin glue was applied over the suture in 7 patients. Three of the 13 patients had large dural defects. CONCLUSIONS: The size of bone and dural defect seems to be an important prognostic factor of episodes of meningitis. The use of fibrin glue to fixate fascia lata graft did not benefit the outcome.

Comparison of Wiltse and classical methods in surgery of lumbar spinal stenosis and spondylolisthesis.

AIM: Minimally invasive approaches to posterior lumbar surgery are available today that can enhance patient comfort by greatly reducing tissue damage and offer better clinical results. However, such methods have not yet gained widespread popularity despite their significant advantages. This study compares the Wiltse method and the classical method of lumbar surgery based a cohort, clinical study of 57 patients. The patients all had degenerative lumbar spinal stenosis and/or spondylolisthesis and had developed multifidus muscular atrophy. MATERIALS AND METHODS: We enrolled 57 patients admitted to our clinic between April 2012 and September 2013 with a diagnosis of degenerative lumbar spinal stenosis and/or spondylolisthesis. These were treated with the classic posterior approach (n=26) or the Wiltse method (n=31). FINDINGS: In the classical method group, the ratio of female to male patients was 20/6 and the mean age was 58.19±10.17 years. A comparison of preoperative and postoperative multifidus muscle cross-sectional measurements (average of right and left) revealed a 36.09% atrophy level in the classical method group and a 26.34% atrophy level in the Wiltse group (p<0.01). However, atrophy development was 18.82% higher in the classical method group (p<0.05) relative to the Wiltse group. CONCLUSION: The Wiltse method is less invasive and causes less tissue damage. It reduces the change of hemorrhage and multifidus muscles and offers a shorter duration of hospitalization with less pain.

Extraosseous, epidural cavernous hemangioma with back pain.

BACKGROUND: Cavernous malformations are characterized by enlarged vascular structures located in benign neural tissues within the cerebellum and spinal cord of the central nervous system. Cavernous hemangiomas (CHs) account for 5% to 12% of all spinal vascular malformations. CASE REPORT: We removed a hemorrhagic thoracic mass in a 40-year-old male patient who presented with progressive neurological deficits. CONCLUSIONS: We found it appropriate to present this case due to its rarity.

Isolated Transverse Clivus Fracture without Neurodeficit: Case Report and Review of Literature.

BACKGROUND: Clivus is a bony surface in the posterior cranial fossa, serving as the support of the brainstem and thus neighboring important structures because of its location. Skull base fractures that cannot be shown by conventional radiography can be clearly imaged by high-resolution bone window computed tomography. CASE REPORT: A 44 years-old male referred to the emergency department because of a traffic accident in the car. His only complaint was a severe neckache. His X-ray examination showed no pathology. The computed tomographic examination showed no parenchymal pathology, but a isolated transverse fracture in the clivus. CONCLUSIONS: The computed tomographic examination showed isolated transverse fracture in the clivus our case presented in this paper is the first case of transverse clivus fracture without additional cranial bone fracture and neurologic deficit in the literature.

A coinsidence, a chance or a misfortune? Hangman's fracture.

William R. Francis and Bassam El-Effendi shared a common ground: they were the first individuals to classify Hangman's Fractures. Interestingly, although they were unaware of each other, they classified and published their findings in the same year, published in the same edition of the same journal (but on different pages). This new classification system was a chance for notoriety for El-Effendi, yet it was a misfortune for Francis. Both physicians graduated in 1973 (from different universities). Also fellows at different universities in 1981, they were also both unaware they studied the same topic. Coincidentally, their paths crossed in the same edition of a journal where their studies were published in the same year, which was unprecedented in the literature. One classification scheme is well-known while the other is almost completely unheard of for no apparent reason other than chance for one and misfortune for the other.

Finite Element Analysis of Bilateral Double Rod Constructs in Thoracolumbar Fractures.

AIM: To evaluate bilateral double rod contructs in thoracolumbar fractures in a Finite Element model MATERIAL and METHODS: A computed tomography of a 35-year old male have been chosen to create a vertebra model and 1/3 of the T12 was removed to create the burst fracture model. In model A, transpedicular polyaxial screws were inserted two levels above and two levels below the burst fracture. On each side the screws were connected with a single rod. In model B, the screws were connected with two rods on each side attached to two lateral connectors. A uniform 150 N axial load and 10 N/m torque was applied on the superior T10. RESULTS: ROM and von Mises stress nephrograms revealed that the bilateral double-rod construct is being the most rigid and that the force on the pedicle screws were significantly lower compared to model A. CONCLUSION: We believe that bilateral double-rod constructs for the stabilization of thoracolumbar fractures have a decreased load on pedicle screws and rods compared to the classic bilateral single rod stabilization system and can lower the risk of implant failure and the risk for secondary complications and revision surgery.

Selective Apical Convex Rod Derotation: A Fast and Secure Technique for the Correction of Adolescent Idiopathic Scoliosis-A Case Series of 38 Patients.

BACKGROUND AND OBJECTIVES: We present a novel technique of selective apical convex rod derotation as an effective and safe maneuver for the correction of adolescent idiopathic scoliosis and give the clinical results of our patients. Adolescent idiopathic scoliosis is the three-dimensional deformity of the spine of more than 10° affecting children from 10 to 18 years. The gold standard for the correction of larger curves is posterior fusion. With the help of osteotomies, the spine becomes mobile and the ideal alignment can be achieved with correction maneuvers. Derotations from the concave side harvest numerous complications such as exacerbation of apical rotation, screw pullout, and implant failure. METHODS: After the transpedicular screws are placed, a short titanium rod is put on the convex-side screws just covering the apex and the screw nuts are loosely tightened. The convex apical rod is held with 2 rod holders and derotation is applied to the rod and the convex spine is pulled toward the midline. After the desired correction is reached, a permanent rod is placed to the concave side and screw nuts are tightened. RESULTS: A total of 38 patients have been included in this study. Preoperative median Cobb angle was 47.19°, postoperative Cobb angle was measured as 18.45°, and 1 year follow-up was 17.25°. Thoracic kyphosis values were 19.07°, 30.52°, and 33.05°, respectively. Lumbar lordosis were measured as 42.63°, 43°, and 45.75°, respectively. CONCLUSION: Selective apical convex rod derotation is an effective treatment of adolescent idiopathic scoliosis with minimal risk for screw pullout, pedicular bursting, or hypokyphosis. Correction results are similar to classic correction maneuvers.

The role of conservative treatment in lumbar disc herniations: WFNS spine committee recommendations.

Objective: To formulate the most current, evidence-based recommendations for the conservative management of lumbar disc herniations (LDH). Methods: A systematic literatüre search was performed 2012-2022 in PubMed/Medline and Cochrane using the keywords ''lumbar disc herniation'' and ''conservative treatment,'' yielding 342 total manuscripts. Screening criteria resulted in 12 final manuscripts which were summarized and presented at two international consensus meetings of the World Federation of Neurosurgical Societies (WFNS) Spine Committee. The Delphi method was utilized to arrive at three final consensus statements. Results and conclusion: s: In the absence of cauda equina syndrome, motor, or other serious neurologic deficits, conservative treatment should be the first line of treatment for LDH. NSAIDs may significantly improve acute low back and sciatic pain caused by LDH. A combination of activity modification, pharmacotherapy, and physical therapy provides good outcomes in most LDH patients.

The New Alternative Technique Outcomes: Atlas Lateral Mass Screw and C2-3 Transfacet Screw Fixation for Complex Atlantoaxial Instability in Patients with Thin C2 Pedicle or High-Riding Vertebral Artery.

OBJECTIVE: The study aimed to evaluate the safety, feasibility, effect on fusion, and clinical efficacy of atlas lateral mass and C2-3 transfacet screw fixation technique, serves as an alternative method to traditional posterior atlantoaxial fixation. METHODS: Patients with atlantoaxial instability who underwent atlas lateral mass and C2-3 transfacet fixation surgery were included. The duration of the surgery and the quantity of blood lost during the operation were recorded. Patients were monitored via X-ray and computed tomography scans to evaluate the degree of fusion at the 1-month and 12-month follow-up. The Neck Visual Analog Scale and Neck Disability Index were evaluated preoperatively, in the postoperative first week, and at the 12-month follow-up for clinical follow-up. RESULTS: A total of 8 patients with atlantoaxial instability due to odontoid fracture or Arnold- Chiari malformation accompanied by bony or vascular abnormalities were included in the study between 2017 and 2024. All 8 patients underwent successful atlas lateral mass and C2-3 transfacet screw fixation, with no neurovascular injury noted during surgery. All patients with fracture exhibited fusion at the 12-month mark, and both the Neck Visual Analog Scale and Neck Disability Index scores demonstrated significant improvement at both the 1-week and 12-month postoperative periods (P < 0.05). CONCLUSIONS: The atlas lateral mass and C2-3 transfacet screw fixation technique, an alternative to conventional posterior fixation, has been demonstrated to be an efficacious method for providing adequate stabilization and fusion in patients with atlantoaxial instability, even in the cases of thin C2 pedicle, high-riding vertebral artery, previous failed surgeries, or reoperation.

Can lumbar paraspinal muscle/fat ratio and spinopelvic parameters predict short-term outcomes after decompressive surgeries in lumbar disc herniation and lumbar spinal stenosis?

Background and Objectives: We aimed to investigate whether the lumbar paraspinal muscle/fat ratio influences the outcomes of patients who had simple decompressive surgeries for lumbar disc herniation (LDH) or lumbar spinal stenosis. We also wanted to see if the spinopelvic parameters change with surgery and whether this change influences the outcomes. Materials and Methods: This was a prospective study on patients with lumbar spinal stenosis (20 patients) and LDH (20 patients) who underwent simple discectomy or decompressive surgery between November 2021 and May 2022. Visual Analog Scale (VAS) for back and leg pain, Oswestry Disability Index, and Japanese Orthopedic Association (JOA) score were performed before and 3 months after surgery. Spinopelvic parameters were measured on whole spine radiographs before and 3 months after surgery. On axial magnetic resonance images, paraspinal muscle volume and muscle/fat ratios were calculated. All data were statistically analyzed with SPSS program. Results: There was a significant improvement in VAS, Oswestry, and JOA scores after surgery. We observed that more preoperative paraspinal muscle mass was positively correlated with lumbar lordosis (LL) and negatively correlated with sagittal vertical axis (SVA), VAS leg scores, and Oswestry scores. Furthermore, we observed a positive correlation between preoperative SVA and VAS leg scores. Conclusion: Despite limited number of patients, and shorter follow-ups, this prospective study demonstrates a correlation among the lumbar paraspinal muscle/fat ratio, preoperative/postoperative spinopelvic parameters, and surgical outcomes. Increased paraspinal muscle ratio was correlated with lower SVA values and increased LL; lower VAS leg scores; higher Oswestry scores which reflects better surgical outcomes.

Temporary 6TH cranial nerve paralysis after accidental durotomy in endoscopic disc surgery.

We present a unique case of 6th nerve palsy following accidental durotomy in endoscopic lumbar spine surgery, which has not been reported in the literature before. A 72- year-old female patient was admitted to our outpatient clinic complaining of right leg pain for 6 months. A 4/5 motor paresis was observed on her right toe with a positive Lasegue test at 45°. On her magnetic resonance imaging (MRI), a L5-S1 disc herniation was detected. The patient was planned for percutaneous endoscopic interlaminar disc surgery. The extruded disc was adherent to the dura. During removal, a dural tear was observed. She was relieved of her right leg pain immediately after surgery, but after 30 min postoperatively, she complained of double vision with left abducens nerve paralysis. On cranial MRI, no abnormality could be observed. Intravenous fluids were administered and the paralysis resolved on the postoperative 24th hour. The patient was discharged from the hospital and did not show any complaints on her follow-ups. A 6th nerve palsy can be caused due to alterations of intracranial pressure or mechanic injury. We believe that the durotomy following removing of the disc fragment caused a rapid drainage of CSF, leading to intracranial hypotension and injury of the abducens nerve. Intracranial pressure should be monitored perioperatively and brisk deteriorations has to result in immediate finishing of the surgery to avoid further secondary damage.

Complications of adult spinal deformity surgery: A literature review.

Purpose: Adult spinal deformity incidence increases accordingly as the population ages. Even though surgery is the best option for the treatment, the complications due to surgery are pretty challenging. This study aims to review the complication rates of adult spinal deformity surgery. Methods: A literature review of the last decade was performed searching for the query "Adult spine deformity and complication." This search yielded 2781 results, where 79 articles were chosen to investigate the complications of adult spinal deformity surgery. In addition, the demographic data, surgical interventions, and complications were extracted from the publications. Results: A total of 26,207 patients were analyzed, and 9138 complications were found (34.5%). Implant failure, including screw loosening, breakage, distal and proximal junctional kyphosis, were the most common complications. The neurologic complications were about 10.8%, and the infection rate was 3.6%. Cardiac and pulmonary complications were about 4.8%. Discussion: Age, body mass index, smoking, osteoporosis, and other comorbidities are the significant risk factors affecting adult spinal deformity surgery. Presurgical planning and preoperative risk factor assessment must be done to avoid complications. Furthermore, intra and postoperative complications affect the patients' quality of life and length of stay, and hospital readmissions. Revision surgery also increases the risk of complications. Conclusion: Good patient evaluation before surgery and careful planning of the surgery are essential in avoiding complications of adult spinal deformity.

Decompression and fusion surgery for osteoporotic vertebral fractures: WFNS spine committee recommendations.

Osteoporotic vertebral fractures (OVF) are common due to aging populations. Their clinical management remains controversial. Although conservative approaches are sufficient in most cases, there are certain conditions where decompression or fusion surgery are necessary. This manuscript aimed to clarify the indications and types of surgeries for OVF. A Medline and Pubmed search spanning the period between 2010 and 2020 was performed using the key words "osteoporotic vertebral fractures and decompression surgery" and "osteoporotic vertebral fractures and fusion surgery." In addition, we reviewed up-to-date information on decompression and fusion in osteoporotic vertebral fracture (OVF) to reach an agreement in two consensus meetings of the World Federation of Neurosurgical Societies (WFNS) Spine Committee that was held in January and February 2021. The Delphi Method was utilized to improve the validity of the questionnaire. A total of 19 studies examining decompression and fusion surgery in OVF were reviewed. Literature supports the statement that decompression and fusion surgery are necessary for progressive neurological deficits after OVF. The Spine Section of the German Society for Orthopedics and Trauma (DGOU) Classification revealed that it might help make surgical decisions. We also noted that in patients planning to undergo surgery to correct significant kyphosis after OVF, several techniques, including multilevel fixation, cement augmentation, preservation of sagittal balance, and avoiding termination at the apex of kyphosis are necessary to prevent complications. Additionally, it became clear that there is no consensus to choose the type of open surgery (anterior, posterior, combined, using cement or bone or vertebral body cage, the levels, and kind of instrumentation). The current literature indicated that implant failure in the osteoporotic spine is a common complication, and many techniques have been described to prevent implant failure in the osteoporotic spine. However, the superiority of one method over another is unclear. Open surgery for osteoporotic vertebral fractures should be considered if neurologic deficits and significant painful kyphosis. The apparent indications of surgery and most ideal surgical technique for OVF remain unclear in the literature; therefore, the decision must be individualized.

Modified Kickstand Rod Technique for the Correction of Adult Idiopathic Scoliosis.

Adult idiopathic scoliosis (ADIS) is the delayed form of adolescent idiopathic scoliosis (AIS) which is defined as a three-dimensional deformity with a lateral curvature of more than 10° in adults with prior history of AIS. Surgery is necessary for patients with symptoms of chronic pain, neuromotor deficits and cardiopulmonary problems with a Cobb angle exceeding 45°. In untreated patients, AIS may lead to ADIS which can cause serious problems like osteoarthritis, progressive deformity and spinal stenosis. In recent years, the kickstand rod technique has been introduced in addition to posterior transpedicular stabilization. A kickstand rod is an additional rod which is placed on a supporting iliac screw which is placed on the superior lateral edge of the ilium on the concave side of the deformity (or in other words on the ipsilateral side of the trunk shift) and is connected with a domino connector to the thoracolumbar junction. The rod is then distracted with the screw nuts locked on the contralateral side to achieve coronal correction. The classic kickstand works as a an additional aid to keep the spine in place during maneuvering. We established a modified kickstand rod technique where we put the rod on the concave side and apply compression between the rod on the screw heads and the kickstand to bring the concavity to the midline. The kickstand was used as a temporary tool like a lever to push the spine medially with compression. We believe that our technique can be a useful alternative for correction of coronal imbalance besides the classic one.

The effects of chronic long-term intermittent hypobaric hypoxia on blood rheology parameters.

The effect of chronic long-term intermittent hypobaric hypoxia (CLTIHH) on blood rheology is not completely investigated. We designed this study to determine the effect of CLTIHH on blood rheology parameters. Present study was performed in 16 male Spraque-Dawley rats that divided into CLTIHH and Control groups. To obtain CLTIHH, rats were placed in a hypobaric chamber (430 mmHg; 5 hours/day, 5 days/week, 5 weeks). The control rats stayed in the same environment as the CLTIHH rats but they breathed room air. In the blood samples aspirated from the heart, hematocrit, whole blood viscosity, plasma viscosity, plasma fibrinogen concentration, erythrocyte rigidity index and oxygen delivery index were determined. The whole blood viscosity, plasma viscosity, hematocrit and fibrinogen concentration values in the CLTIHH group were found to be higher than those of the control group. However, no significant difference was found in erythrocyte rigidity index and oxygen delivery index between the groups. Our results suggested that CLTIHH elevated whole blood viscosity by increasing plasma viscosity, fibrinogen concentration and hematocrit value without effecting the erythrocyte deformability. Hence, CLTIHH that may occur in intermittent high altitude exposure and some severe obstructive sleep apnea (OSA) patients may be responsible for hemorheologic changes in those subjects.

Alterations of central hypercapnic respiratory response induced by acute central administration of serotonin re-uptake inhibitor, fluoxetine.

Long-term neurochemical changes are responsible for therapeutic actions of fluoxetine. The role of increased central concentration of serotonin by inhibiting its re-uptake via fluoxetine on the central hypercapnic ventilatory response is complex and little is known. We aimed to research the effect of acute intracerebroventricular (ICV) injection of fluoxetine on hypercapnic ventilatory response in the absence of peripheral chemoreceptor impulses and the role of 5-HT2 receptors on responses. Eighteen anesthetized albino rabbits were divided as Fluoxetine and Ketanserin groups. For ICV administration of fluoxetine and ketanserin, a cannula was placed in the left lateral ventricle by the stereotaxic method. Respiratory frequency (fR), tidal volume (V(T)) and ventilation minute volume (V(E)) were recorded in both groups. ICV fluoxetine (10.12 mmol/kg) injection during normoxia caused significant increases in V(T) and V(E) (both P < 0.01) in the fluoxetine group. When the animals were switched to hypercapnia f/min, V(T) and V(E) increased significantly. The increases in percentage values in V(T) and V(E) in Fluoxetine + Hypercapnia phase were higher than those during hypercapnia alone (P < 0.01 and P < 0.05, respectively). On blocking of 5-HT2 receptors by ketanserin (0.25 mmol/kg), the ventilatory response to Fluoxetine was abolished and the degree of increases in V(T) and V(E) in the Ketanserin + Hypercapnia phase were lower than those during hypercapnia alone (P < 0.01 and P < 0.001, respectively). We concluded that acute central fluoxetine increases normoxic ventilation and also augments the stimulatory effect of hypercapnia on respiratory neuronal network by 5-HT2 receptors in the absence of peripheral chemoreceptor impulses.