[Three-Dimensional Nonlinear Finite Element Modeling and Analysis of Concomitant Atlanto-Occipital Fusion and Atlantoaxial Joint Dislocation].

OBJECTIVE: To establish, with finite element technology, a three-dimensional nonlinear finite element model of the normal occipital bone, atlas and axis and a three-dimensional nonlinear finite element model of concomitant atlanto-occipital fusion and atlantoaxial dislocation, providing a biomechanical method for clinical research on the upper cervical spine. METHODS: Finite element analysis was conducted with the CT data of a 27-year-old male volunteer, and a three-dimensional nonlinear finite element model, i.e., the normal model, of the normal occipital bone, atlas and axis was established accordingly. Finite element analysis was conducted with the CT data of a 35-year-old male patient with concomitant atlanto-occipital fusion and atlantoaxial dislocation. Then, the ideal state of a simple ligament rupture under high load was generated by computer simulation, and a three-dimensional nonlinear finite element model of concomitant atlanto-occipital fusion and atlantoaxial dislocation was established, i.e., the atlanto-occipital fusion with atlantoaxial dislocation model. For both models, a vertical upward torque of 1.5 N·m was applied on the upper surface of the occipital bone. Through comparative analysis of the two models under stress, the data of the range of motion (ROM) for flexion, extension, lateral bending, and rotation were examined. In addition, stress and deformation analysis with 1.5 N·m torque load was conducted to validate the effectiveness of the two three-dimensional nonlinear finite element models established in the study. RESULTS: When the normal model established in the study was under 1.5 N·m torque load, it exhibited a maximum ROM for each unit of flexion, extension, and the ROM approximated the experimental measurement results of human mechanics, confirming the validity of the simulation. The stress and deformation results of the model were consistent with the basic principles of mechanics. The moment-angular displacement of the model showed obvious nonlinear characteristics. Compared with the normal model, the atlanto-occipital fusion with atlantoaxial dislocation model showed reduced ROM of the atlanto-occipital joint under a torque of 1.5 N·m, while the ROM of the C1-C2 joint for the four conditions of flexion, posterior extention, lateral bending, and rotation under load, with the exception of rotating motion, was greatly increased compared with that of the normal model, which was in line with the actual clinical performance of the patient. CONCLUSION: The atlanto-occipital fusion with atlantoaxial dislocation model and the three-dimensional nonlinear finite element model of the normal occipital bone, atlas and axis were successfully established by finite element technology. The models had valid simulation and reliable kinematic characteristics, and could be used as a reliable tool to simulate clinical diseases.

[A Case Report of Ectopic Sweat Duct Ectasia of Conus Medullaris].

A healthy 52-year-old woman presented with 10-days history of back pain. Neurologic testing failed to detect any functional deficits in the upper and lower extremities, and the patient had a full range of cervical spine motion without associated pain. Spinal CT and MRI revealed a well-circumscribed intradural mass located at conus medullaris. The operation of L1 hemilaminectomy was performed, and pathological examination discovered dilatation of sweat ducts and suggested the diagnosis of ectopic sweat duct ectasia. IHC staining in epithelia immunophenotype showed: pan-cytokeratin (PCK)(+), epithelia membrane antigen (EMA)(+), P63(+), cytokeratin 5/6 (CK5/6)(+), gross cystic disease fluid protein 15 (GCDFP15)(-). Intraspinal ectopic sweat duct ectasia is extremely rare, which has not been reported in the literature to date.

One-stage removal of a giant thoracic paraspinal shamrock-shaped schwannoma via modified hemilaminectomy and posterolateral thoracotomy.

BACKGROUND CONTEXT: Paraspinal neurogenic tumors in the thoracic region are not a rare clinical entity in neurosurgical practice. They usually consist of intrathoracic and intraspinal parts, namely dumb-bell type. However, in some rare cases, they might display a bidirectional extraspinal growing pattern, compromising three components with intraspinal, intrathoracic, and subcutaneous parts, thus appearing to be shamrock-like. Despite its benign nature, the removal of this type of tumor could be challenging for both neurosurgeons and thoracic surgeons, especially when the tumor has grown to an enormous size. PURPOSE: We present a case of a giant paraspinal shamrock-shaped schwannoma in the T9-T12 level resected completely by one-stage combined surgery of hemilaminectomy and posterolateral thoracotomy performed by an interdisciplinary team of neurosurgeons and thoracic surgeons. STUDY DESIGN/SETTING: Operating room of a large tertiary medical center where expertise and equipment of neurosurgery, thoracic surgery, and neuroanesthesia are readily available. METHODS: Under generalized anesthesia, the patient was intubated with a double-lumen endotracheal tube to allow one-lung ventilation during the thoracotomy, and he was then placed in the left lateral position. Because of the giant subcutaneous mass, the normal hemilaminectomy could not be carried out like it usually would be. Thus, we did slight modification to the standard hemilaminectomy; first, by elevation of a skin flap to allow in situ excision of the subcutaneous portion of the tumor, then followed by a standard unilateral laminectomy to remove the intraspinal portion, done by neurosurgeons, and finally, posterolateral thoracotomy to remove the intrathoracic part, performed by a thoracic team. RESULTS: The postoperative magnetic resonance imaging scan showed complete removal of the tumor, and the patient experienced an improvement in lower extremity muscle weakness with no new neurological deficits. CONCLUSIONS: This is the first case to demonstrate the removal of giant paraspinal shamrock-shaped schwannoma in the thoracic level. The combined approach of modified hemilaminectomy and posterolateral thoracotomy was proven to be appropriate in managing such cases, making this procedure a potential addition to present methods.

Minimally-invasive treatment of communicating hydrocephalus using a percutaneous lumboperitoneal shunt.

OBJECTIVE: To investigate the clinical value of a minimally-invasive treatment of communicating hydrocephalus using a percutaneous lumboperitoneal (LP) shunt. METHOD: The clinical and long-term follow-up data of 256 patients suffering from communicating hydrocephalus and undergoing percutaneous LP shunt during 1998 to 2008 were retrospectively analyzed. RESULTS: After the follow-up, which lasted 6 months to 10 years, 219 cases of communicating hydrocephalus recovered well (ventricular size returned to normal and symptoms completely disappeared), 25 cases were brought under control (ventricle size reduced by 50% and symptoms partially abated), and 12 cases showed no obvious changes. Fifteen obese subjects needed modifications of the shunt due to the obstruction of the abdominal end following wrapping, and one subject underwent extubation as the subject was unable to tolerate stimulation of the cauda equina. The effectiveness of shunting was 91.40% and the probability of shunt-tube obstruction, which occurs predominantly in the abdominal end, was only 5.85%, far lower than that of ventriculoperitoneal (VP) shunt. Three subjects had a history of infection following VP shunting. CONCLUSION: LP shunting is minimally invasive and effective in treating communicating hydrocephalus, with fewer complications.

[Clinical analysis of 542 intraspinal tumors microsurgically resected by hemilaminectomy].

OBJECTIVE: To investigate the advantages, disadvantages and indications of hemilaminectomy for microsurgical resection of intraspinal tumors. METHODS: We retrospectively reviewed and analyzed the clinical data of 542 cases of intraspinal tumors microsurgically resected by hemilaminectomy during the period from January 2005 to December 2008. RESULTS: The tumors were totally removed in 501 cases (92%). The average postoperative stay was 5.2 days. Postoperative follow-ups ranged from 6 months to 3 years (mean 9 months). The clinical symptoms of 495 cases (91%) improved. No tumor recurrence was reported in the totally removed cases. The stability of vertebral column was excellent and there was no spinal deformity in these patients. CONCLUSION: With many advantages of minimal trauma, milder postoperative reaction, shorter length of recovery and better spinal stabilization, hemilaminectomy can be used for microsurgical resection of all lateralized epidural, subdural-extramedullary and some benign intramedullary tumors.

The epidemiology and clinical management of craniocerebral injury caused by the Sichuan earthquake.

BACKGROUND: Earthquake is one of the most devastating natural disasters that threaten human lives. Worldwide more than 3 million deaths have been caused by earthquakes in recent 20 years. AIM: To analyze clinical features of head injuries after Sichuan earthquake. MATERIALS AND METHODS: From May 12 to June 12, 2008, Departments of Neurosurgery in major Hospitals in Sichuan Province admitted 1368 patients with head injuries caused by the Sichuan earthquake; the epidemiology, mechanism, severity, complications, treatments and outcome of head injury were retrospectively analyzed. RESULTS: Of the 1,368 patients, 755 were men and 613 women. Collapsing building was the most important cause of head injury. Most of the patients, 85% had mild to moderate head injury. The type of injury was open scalp injury in 65% of patients. About 47% of the head-injured patients were admitted within 72 h after earthquake. Skeletal bone fracture was the most common associated injury (9%). Only 98 patients received surgery. Glasgow Outcome Scale on discharge or transfer was: 5 in 1,121 (82%) patients, 4 in 173 (13%) patients, and 3 or less in 74 (5%) patients. Overall 33 (2%) patients died. CONCLUSIONS: The characteristics of Sichuan earthquake-related head injury are quite distinct. Early standardized treatment is important to have better outcomes.

[Efficacy of total removal or subtotal removal combined gamma knife radiation on giant pituitary adenoma: a report of 160 cases].

BACKGROUND & OBJECTIVE: Pituitary adenoma, a kind of familiar benign intracranial tumor, is mainly treated with surgical operation, medication, and radiation. However, the outcome, especially for giant pituitary adenoma, is not very satisfactory. This study was to explore the efficacy of total tumor removal or subtotal tumor removal combined gamma knife radiation on giant pituitary adenoma. METHODS: Clinical data of 160 giant pituitary adenoma patients were analyzed. Of the 160 patients, 90 received total tumor removal, 70 received subtotal tumor removal combined gamma knife radiation. The symptom improvement, tumor size change, serum hormone concentration, complications after treatment, and so on, of the 2 groups were compared. RESULTS: At 12 months after treatment, the efficiency rate, recurrence rate, and mortality were 74.4%, 31.1%, and 3.3%, respectively, in total tumor removal group; however, the efficiency rate reached 91.4%, the recurrence rate decreased to 11.4%, and no patients died in combined therapy group. The follow-up results at 24 months after treatment and at present (over 5 years) showed that though the efficiency rate had descended and recurrence rate or mortality had ascended in both groups, the efficacy of combined therapy was obviously better than that of total tumor removal. The decrease of serum hormone concentration was more obvious in combined therapy group than in total tumor removal group at 12 months after treatment. Moreover, total tumor removal group had more serious complications than combined therapy group after treatment. CONCLUSION: Subtotal tumor removal combined gamma knife radiation is better than total tumor removal for giant pituitary adenoma.