Right ventricular stroke volume variation: a tool to assess right ventricular volume responsiveness.

BACKGROUND: So far, only left ventricular functional preload indices are used as a routine to assess volume responsiveness. Right ventricular (RV) functional preload indices have been described, but offer no continuous monitoring. METHODS: Following ethical approval, a pressure-induced right ventricular failure (RVF) was induced with continuous infusion of a thromboxane-A2-analogue (U46619) in 15 anesthetized and ventilated pigs. Before and after increasing mean pulmonary artery pressure (MPAP) by 50%, right ventricular stroke volume variation (RVSVV) was assessed with an ultrasonic pulmonary artery flow probe. Measurements were repeated following volume depletion (- 300 mL) and stepwise retransfusion (200 mL of whole blood and 200 mL of a colloid solution). RESULTS: A significant and systematic increase in RVSVV during induction of RVF was observed. Volume depletion led to an increase in RVSVV and re-transfusion led to a decrease in RVSVV. RVSVV was higher and a significant decrease in RVSVV was present in all animals experiencing an increase in CO by more than 5% during retransfusion. CONCLUSION: RVSVV seems to reflect volume requirement of the right ventricle and it might prove a reliable parameter to assess volume responsiveness in RVF.

[Development of epidural spinal cord stimulation. Fortieth anniversary of the first implantation in Germany]. / Entwicklung der epiduralen Rückenmarkstimulation. 40 Jahre seit der Erstimplantation in Deutschland.

Spinal cord stimulation is nowadays an established therapy for various neuropathic and vasculopathic pain syndromes after more conservative measures have failed. However, 40 years ago, only 5 years after the first worldwide implantation in the US, this therapy was promoted in Germany. In 1972, the first devices were implanted in the Departments of Neurosurgery at the Universities Hannover and Freiburg. These pioneering efforts and the establishment of the therapy are intimately associated with three names: Jörg-Ulrich Krainick, Uwe Thoden, and Wolfhard Winkelmüller. Nowadays about 1700 spinal cord stimulation systems are implanted annually in Germany. The development of spinal cord stimulation from the beginnings up to now taking into special consideration the early years in Germany are presented.

[Immunonutrition after trauma]. / Immunonutrition nach Trauma.

Immunonutrition may be superior to standard clinical nutrition in specific clinical situations. After severe trauma, an enteral immuno-enhancing diet, enriched with arginine, omega-3 fatty acids, and nucleotides, decreases infectious complications. During acute respiratory distress syndrome, a continuous enteral diet with high-dose omega-3 fatty acids, gamma-linolenic acid, and antioxidants improved clinical outcome. Glutamine should be administered enterally or parenterally whenever total parenteral nutrition is indicated.

Respiratory systolic variation test in acutely impaired cardiac function for predicting volume responsiveness in pigs.

BACKGROUND: Predicting the response of cardiac output (CO) to volume administration remains difficult, in particular in patients with acutely compromised cardiac function, where, even small amounts of i.v. fluids can lead to volume overload. We compared the ability to predict volume responsiveness of different functional haemodynamic parameters, such as pulse pressure variation (PPV), stroke volume variation (SVV), the static preload parameter right atrial pressure (RAP), and global end-diastolic volume (GEDV) with the recently proposed respiratory systolic variation test (RSVT) in acutely impaired cardiac function. METHODS: In 13 mechanically ventilated pigs, cardiac function was acutely reduced by continuous application of verapamil to reach a decrease in peak change of left ventricular pressure over time (dP/dt) of 50%. After withdrawal of 20 ml kg(-1) BW blood to establish hypovolaemia, four volume loading steps of 7 ml kg(-1) BW using the shed blood and 6% hydroxyethylstarch 130/0.4 were performed. Volume responsiveness was considered as positive, if CO increased more than 10%. RESULTS: Receiver operating characteristic curve analysis revealed an area under the curve (AUC) of 0.88 for the RSVT, 0.84 for PPV, 0.82 for SVV, 0.78 for RAP, and 0.77 for GEDV. CONCLUSIONS: Functional parameters of cardiac preload, including the RSVT, allow prediction of fluid responsiveness in an experimental model of acutely impaired cardiac function.

[The endoscopic management of the cubital tunnel syndrome--an anatomical study and first clinical results]. / Die endoskopische Dekompression des Kubitaltunnelsyndroms--Anatomische Grundlagen und erste klinische Ergebnisse.

Besides the carpal tunnel syndrome, the cubital tunnel syndrome (CuTS) represents the second most frequent nerve entrapment syndrome. The current gold standard for surgical therapy consists of simple open decompression. Recently, an endoscopic procedure involving long-distance decompression of the ulnar nerve has been developed and this is the topic of the present study. The first part of this paper describes preliminary anatomic investigations on 22 cadaver arms. In every sample we observed a thickening of the submuscular membrane between the heads of the flexor carpi ulnaris (FCU) which surrounds the ulnar nerve. This was especially the case for the first 10 cm from the medial epicondyle In the second part we report our experiences with this endoscopic decompression procedure in 36 patients. With this endoscopic decompression we achieved good to very good results according to the Bishop classification in 28 patients (78%). On the basis of anatomic considerations and our current experience, the endoscopic procedure seems to represent a promising alternative to simple decompression.

Foramen magnum meningiomas--experience with the posterior suboccipital approach.

The aim of this study is to analyse short- and long-term results after surgical treatment of foramen magnum meningiomas and to identify the possible advantages of the posterior suboccipital approach over lateral and anterior approaches. Between 1992 and 2006, 16 patients with foramen magnum meningiomas were operated on in our institution, and in all cases a posterior suboccipital approach was utilised with lateral extension of the bone opening according to the position of the tumour. In 14 patients, intraoperative monitoring of the lower cranial nerves was performed. Localisation of the tumours was ventral (3), ventrolateral (10), dorsal (1) and dorsolateral (2). Mean age of the patients was 61 years (ranging from 40 to 85 years). Preoperative and postoperative function was classified according to the McCormick scale. We found in eight patients a postoperative upgrading of at least one grade, in five patients an unchanged status and a deterioration in only two patients. Complete removal of the tumour was possible in 14 cases (Simpson 1-2). The follow-up period varied from 24 to 119 months (mean 43.5 months), during this time there were no recurrences. Removal of foramen magnum meningiomas can be performed safely today with the use of microsurgical techniques and intraoperative monitoring. In our experience, the posterior suboccipital approach is suitable for the majority of these tumours.

Intraneural perineuriomas; a rare entity. Clinical, surgical and neuropathological details in the management of these lesions.

OBJECTIVE: Perineuriomas are rare benign peripheral nerve sheath tumors, which have only been included in the WHO classification system since 2000. They are divided into intraneural perineuriomas and soft tissue tumors. Intraneural perineuriomas were previously known as localized hypertrophic neuropathies. Because of their rarity there are only case reports in the literature. METHODS: Between 1992 and 2006 surgery was performed on four patients suffering from intraneural perineuriomas in our hospital. All patients were males, aged five, ten, twenty and twenty-nine years old. One of the tumors occurred in the ulnar nerve, one in the common peroneal part of the sciatic nerve and two of them in the radial nerve. In a retrospective study the clinical, electrophysiological and imaging data of the patients was analyzed. Two of these patients had previously been treated with decompression and neurolysis of the nerve for the suspicion of a nerve compression syndrome. Revisions were necessary following progressive neurological deterioration postoperatively. Explorations of the nerves showed nerve tumors. The tumors were resected and nerve grafting was performed. CONCLUSIONS: These tumors tend to affect the nerves of the upper extremities in children or young adults. The predominant symptom is a slow-progressive paralysis. Two of the four patients showed a partial improvement of their motor and sensorial nerve deficits in the long-term follow-up following complete tumor resection and interpositional autologous nerve grafts. No relapse could be observed. In cases of slow-progressive neurological deficits of a peripheral nerve in young patients the differential diagnosis should include the intraneural perineuriomas.

Neurosurgical management of previously coiled recurrent intracranial aneurysms.

OBJECTIVE: Endovascular treatment of cerebral aneurysms with detachable coils has proven to be a save and effective treatment. But long-term recurrence due to aneurysm regrowth or coil compaction has been reported in up to thirty percent of cases. Therefore a growing number of previously coiled aneurysms have to be retreated by coiling or, in some circumstances, by clipping. We present a consecutive series of ten patients who underwent surgical clipping for recurrent aneurysms after primary coil embolization. METHODS: During a 4-year period ten patients with intracranial aneurysms previously treated by coil embolization underwent surgery for clipping of recanalized aneurysms. All aneurysms were located in the anterior circulation (internal carotid artery [ICA], 2; middle cerebral artery [MCA], 3; anterior communicating artery [AcomA], 5). Clinical data and imaging studies of the patients were analyzed retrospectively. RESULTS: All recurrences were detected by routine control angiograms within a median period of 14 months after primary treatment. In three aneurysms treated for SAH dense arachnoid scarring around the aneurysm sac was noted. In four cases, coils were found intraoperatively to be extruding through the aneurysm sac into the subarachnoid space. Each aneurysm could be clipped without affecting the perfusion of the parent vessel. In one patient the aneurysm sac including the coil package was resected. In one patient one of the central anteromedial arteries was injured during dissection due to dense arachnoid scarring because of prior SAH. As a consequence infarction of the head of the caudate nucleus without neurological compromise was observed on follow-up CT scans. Another patient developed transient aphasia due to vasospasm in the early postoperative period with complete restitution. In the end all patients had an uneventful recovery. Removal of the coil package was not necessary in most cases. Clipping of the aneurysm neck was possible even in cases with coil dislocation into the parent vessel. CONCLUSION: Clipping of previously coiled aneurysms is a unique problem for vascular neurosurgeons. In most cases clipping is feasible. Clipping should still be considered as a definite treatment option in previously coiled recurrent aneurysms. Results in this small series were good.

[Subcranial resection of malignant tumors infiltrating the anterior skull base]. / Subkranialer Zugang bei Malignomen mit Beteiligung der Frontobasis.

BACKGROUND: Survival and quality of life after subcranial resection of malignant tumors infiltrating the anterior skull base should be evaluated. METHODS: Data were acquired retrospectively from patient charts and by telephone interview. Quality of life was assessed with the EORTC QLQ30 and H&N35 modules. RESULTS: From 1996 to 2004, 19 patients (mean age 52 years, 4 woman, 15 men) were surgically treated via a subcranial approach. Fifteen patients suffered from advanced carcinoma, 3 from advanced esthesioneuroblastoma, and 1 patient had a fibrosarcoma. Fifteen patients received adjuvant radiotherapy. During the mean follow-up period of 44 months (12-109 months), 6 patients died, 1 unrelated to the tumor. The probability to survive 5 years was 50 %, the mean survival time was 72 months. Anosmia was reported by 18 of 19 patients. A tension pneumocephalus was observed in 2 patients, one with lethal outcome, decreased vision in 1 patient, loss of vision in 1, persisting diplopia in 1, deep wound infections in 2, and CSF leak in 2 patients. Quality of life was assessed on the average 36 months following end of therapy and did not differ substantially from other patients with head-neck malignancies. CONCLUSION: Most, malignant tumors infiltrating the anterior skull base can be treated curatively. The treatment outcome is well comparable to other head and neck tumors of corresponding stage.

Complications of transpedicular screw fixation in the cervical spine.

Today, posterior stabilization of the cervical spine is most frequently performed by lateral mass screws or spinous process wiring. These techniques do not always provide sufficient stability, and anterior fusion procedures are added secondarily. Recently, transpedicular screw fixation of the cervical spine has been introduced to provide a one-stage stable posterior fixation. The aim of the present prospective study is to examine if cervical pedicle screw fixation can be done by low risk and to identify potential risk factors associated with this technique. All patients stabilized by cervical transpedicular screw fixation between 1999 and 2002 were included. Cervical disorders included multisegmental degenerative instability with cervical myelopathy in 16 patients, segmental instability caused by rheumatoid arthritis in three, trauma in five and instability caused by infection in two patients. In most cases additional decompression of the spinal cord and bone graft placement were performed. Pre-operative and post-operative CT-scans (2-mm cuts) and plain X-rays served to determine changes in alignment and the position of the screws. Clinical outcome was assessed in all cases. Ninety-four cervical pedicle screws were implanted in 26 patients, most frequently at the C3 (26 screws) and C4 levels (19 screws). Radiologically 66 screws (70%) were placed correctly (maximal breach 1 mm) whereas 20 screws (21%) were misplaced with reduction of mechanical strength, slight narrowing of the vertebral artery canal (<25%) or the lateral recess without compression of neural structures. However, these misplacements were asymptomatic in all cases. Another eight screws (9%) had a critical breach. Four of them showed a narrowing of the vertebral artery canal of more then 25%, in all cases without vascular problems. Three screws passed through the intervertebral foramen, causing temporary paresis in one case and a new sensory loss in another. In the latter patient revision surgery was performed. The screw was loosened and had to be corrected. The only statistically significant risk factor was the level of surgery: all critical breaches were seen from C3 to C5. Percutaneous application of the screws reduced the risk for misplacement, although this finding was not statistically significant. There was also a remarkable learning curve. Instrumentation with cervical transpedicular screws results in very stable fixation. However, with the use of new techniques like percutaneous screw application or computerized image guidance there remains a risk for damaging nerve roots or the vertebral artery. This technique should be reserved for highly selected patients with clear indications and to highly experienced spine surgeons.

[Is surgery likely to be successful as a treatment for traumatic lesions of the superficial radial nerve?]. / Ist ein chirurgisches Vorgehen bei traumatischen Läsionen des Ramus superficialis N. radialis Erfolg versprechend?

In the last 10 years 22 patients with lesions of the superficial branch of the radial nerve have been treated surgically in our neurosurgical department. The patients' main complaints were burning pain and paraesthesia in the region supplied by the superficial branch of the radial nerve. In most cases the lesion was due to tendolysis performed earlier to treat de Quervain tendovaginitis stenosans. In 8 cases external neurolysis was done with conservation of continuity; in 4 cases the nerve was reconstructed after resection of the neuroma (end-to-end-suture or implantation of a vicryl conduit); and in 10 cases the neuroma was resected and transposition of the proximal nerve end was performed. Nineteen patients were available for evaluation of the postoperative results, after an average follow-up of 51 months. Surprisingly, only 5 reported good subjective improvement of pain after surgery. Seven patients reported an unchanged status postoperatively, and in 1 case the pain was even worse after the surgical intervention. Satisfactory results (complete or partial pain relief in 75% of cases) was found to have been achieved in the subgroup of patients treated by resection of the neuroma of the superficial branch of the radial nerve and transposition of the nerve stump. In conclusion, we recommend caution when surgical interventions are considered for traumatic lesions of the superficial radial nerve, because the prospects of success are limited. In addition, we do not consider nerve reconstruction desirable in these circumstances.

Brain tumour surgery in the vicinity of short-term memory representation--results of neuronavigation using fMRI images.

OBJECTIVE: Functional information concerning the surrounding brain is mandatory for a good clinical outcome in brain tumour surgery. The value of fMRI to detect the motorcortex and Broca's area is widely accepted today. If an appropriate paradigm is used, short-term memory areas can be visualized as well. Obviously this information must be integrated into cranial neuronavigation for an appropriate intra-operative use. We report our first experiences with the direct integration of short-term memory fMRI into cranial neuronavigation. METHOD: From January 2001 to March 2002 14 patients were operated on for intracranial tumours with short-term memory fMRI imaging, using the "two-back-paradigm". Both pre- and postoperatively, the short-term memory of all patients was tested additionally by a standardized test battery including 16 different verbal and visuo-spatial items. RESULTS: In all 14 patients the general level of working memory capacity was preserved after surgery. The visuo-spatial performance was kept unchanged or deteriorated slightly, the alertness slightly worsened as well, but we found an improvement in verbal test items. CONCLUSION: The two-back paradigm is able to visualize verbal memory tasks in fMRI. For visuo-spatial items, a new paradigm has to be designed. In contrast to deep seated brain lesions, focal cortical impairments do not lead to obvious and serious memory deficits. Therefore, the aim of gross total tumour removal has to be balanced against the aim of preservation of short-term memory fields. Nevertheless, the knowledge of the localization of cortical short-term memory fields may combine both aims during navigated brain tumour surgery, thus preserving the patient with a better quality of life.

[Neurogenic thoracic outlet syndrome. Long-term results of supraclavicular decompression]. / Neurogenes Thoracic-outlet-Syndrom. Langzeitergebnisse der supraklavikulären Dekompression.

OBJECTIVES: Neurogenic thoracic outlet syndrome (TOS) is one of the most controversial entrapment syndromes of the upper extremity. There are two different surgical approaches for its primary surgical treatment: supraclavicular decompression and transaxillary first rib resection. The aim of this study was to evaluate long-term results and surgical risks of the former. METHODS: This retrospective long-term study examines a series of 50 supraclavicular decompressions in 45 patients. Follow-up was for at least 24 months. All patients were reexamined regularly in nonstandardized fashion. Finally, each patient underwent a telephone interview with a standardized questionnaire. RESULTS: There was a significant deterioration of primary results during follow-up. About 30.0% of cases worsened within 24 months after operation. In the long run, about 80.0% of cases showed improvement of symptoms (26.0% excellent, 36.0% good, 18.0% moderate). The complication rate was 4.0%. CONCLUSION: Due to secondary deterioration of treatment during follow-up, only long-term studies are suited for the examination of neurogenic TOS. Results after supraclavicular decompression are satisfactory, and the complication rate is low.

[Results of simple fragment excision in lumbar disc surgery]. / Ergebnisse der alleinigen Sequestrektomie bei lumbaler Bandscheibenoperation.

BACKGROUND: While performing microsurgical disc excision, usually the sequestrated disc fragments as well as loosened or degenerated parts of the nucleus pulposus are removed. It is controversial whether this strategy is always necessary. The aim of this study was to examine this question based on clinical results. MATERIAL AND METHODS: Prospectively all relevant data from 149 consecutive patients after sequestrectomy were collected including the clinical course of the patients with a mean follow-up of 2.3 years. A detailed analysis of the actual pain status, the functional capacity and possible additional spinal operations was performed. RESULTS: During early follow-up, there was one superficial wound infection, which was treated conservatively. The success rate, as measured by patient self-assessment, was 62% for excellent and good and 25% for fair results; 13% of the patients treated declared a poor result having no benefits from surgery. The average FFbH score during follow-up was 74% (100% means no functional restriction). Radicular pain and low back pain had the same intensity on the average, in contrast to some other investigations, where low back pain was lower than radicular pain [14]. Of the 149 patients, 4 underwent a second spine surgery at the same level, 2 of which were recurrent disc herniations (=1.3%). CONCLUSION: Simple fragment excision revealed similar results compared to standard microdiscectomy. There was an especially low number of recurrences in contrast to former reports [16]. This was probably caused by the conscientious selection of patients for sequestrectomy according to well-defined criteria. Whether simple sequestrectomy can effectively treat an additional low back pain component must be clarified by further prospective studies.

[Management of iatrogenic lesions of the spinal accessory nerve]. / Management iatrogener N.-accessorius-Läsionen.

Lesions of the spinal accessory nerve are usually iatrogenic, especially after lymph node extirpation on the neck. Between 1994 and 2003, 31 patients were operated on in the Neurosurgical Department of the University of Ulm for iatrogenic lesions of the XIth cranial nerve. Of 31 patients, 22 had undergone a previous lymph node extirpation, 2 had been injured during a selective peripheral denervation for spasmodic torticollis, and the other 7 patients by different causes. The neurosurgical intervention was performed 0-19 months after trauma (mean 7.2 months). All patients showed paresis/atrophy of the trapezius muscle, and the abduction of the shoulder was markedly reduced. Additional neck and/or shoulder pain was present in 29 of 31 cases. In seven cases, the nerve was compressed by scar tissue and subsequently treated by external neurolysis. Ten patients underwent an end-to-end anastomosis; autologous sural nerve grafting was necessary in 13 cases. After a mean follow-up of 12.6 months, 7 of 31 patients completely recovered. Of 31 patients, 19 experienced partial relief of pain and weakness. Only five patients remained unchanged. The clinical findings after autologous nerve grafting, end-to-end reconstruction, or external neurolysis did not show any significant differences. Microsurgical reconstruction of iatrogenic injury of the spinal accessory nerve is very promising if the interval between trauma and surgical revision is less than 6 months. Up to 12 months, partial recovery can be achieved. Outcome after longer delay is unsatisfactory.

[Spinal intramedullary tumors. When is surgical treatment indicated?]. / Spinale intramedulläre Tumoren Wann ist die operative Behandlung angezeigt?

OBJECTIVE: Timing of surgery in patients with intramedullary tumors is the subject of controversy. The aim of this retrospective study is to evaluate whether patients with intramedullary ependymomas and astrocytomas have a better postoperative prognosis without or with slight preoperative deficits than those with severe preoperative neurological disturbances. PATIENTS AND METHODS: During a period of 8.5 years (January 1992-August 2000), 34 patients with intramedullary tumors underwent surgery in our Neurosurgical Department. Among them there were five astrocytomas WHO grade II and ten ependymomas WHO grade II. Recurrences were observed in two patients with astrocytomas and one patient with ependymoma. Pre- and postoperative functional performance was classified according to the McCormick scale in grade I-IV (grade I: neurologically normal or mild focal deficit and grade IV: severe neurological deficits and without functional independence). The follow-up period varied from 4 to 76 months (mean: 27.9 months). RESULTS: All seven grade I patients remained unchanged after surgery. Two of four grade II patients improved to grade I; two deteriorated to grade III. Two of three grade III and IV patients remained unchanged and another one deteriorated from grade III to IV. CONCLUSION: At the best, intramedullary astrocytomas and ependymomas should be operated when symptoms are mild. Early surgery can achieve good functional outcome.

[Iatrogenic nerve injuries. Part 1: Frequency distribution, new aspects, and timing of microsurgical treatment]. / Iatrogene Nervenverletzungen. Teil 1: Häufigkeitsverteilung, neue Aspekte und Zeitraster der mikrochirurgischen Versorgung.

OBJECTIVE: The aim of this study was to analyze the number and types of iatrogenic nerve injuries operated on during a 13-year period at a relatively busy nerve center. METHOD: Retrospective analysis was done of 191 cases surgically treated because of iatrogenic nerve injuries. RESULTS: Most iatrogenic nerve injuries occurred after surgical procedures. As a rule, symptoms and signs appeared immediately after the procedure. Single nerves most often involved were the spinal accessory nerve at the neck ( n=27), most frequently after lymph node biopsy, and the median nerve in the carpal tunnel ( n=25), usually after carpal tunnel release and most frequently after endoscopic technique. Following in frequency are the common peroneal nerve ( n=16), superficial sensory radial nerve ( n=13), genitofemoral ( n=12), and superficial peroneal and tibial nerves ( n=9 each). Clinical improvement after neurosurgical intervention appeared in 70% of cases. Frequently iatrogenic nerve lesions are referred with significant delay, that is, not during a time interval deemed appropriate for surgical intervention. CONCLUSION: Iatrogenic nerve lesions must be recognized in a timely manner and should be operated upon as early as other traumatic nerve injuries to ensure best chances for successful recovery.

Surgical therapy of symptomatic arachnoid cysts - an outcome analysis.

BACKGROUND: Arachnoid cysts may present with various symptoms and in different locations. Optimal treatment is still controversial, although cyst fenestration or shunt insertion are recognized as standard procedures. In this retrospective analysis the authors sought to determine which factors influence the outcome after surgery of symptomatic arachnoid cysts. METHODS: 37 patients (24 male, 13 female, mean age 40.2 years) were treated within a ten year period in our institution. Mean follow-up was 39 months; follow-up was done on an ambulatory basis. For analysis patient charts were reviewed and cranial CT scans or MR investigations were examined to determine pre- and postoperative cyst volumes. Clinical outcome was graded into four subgroups using a scale based on the patients self-rating of success. Different factors were studied concerning their influence on outcome. FINDINGS: Fenestration was performed in 28 cases, cysto-peritoneal or cysto-atrial shunting in 9 cases. A favourable outcome (subgroups 3 and 4) was achieved in 19 of 28 patients (fenestration) and in 6 of 9 patients (shunting), respectively. Mean reduction of the cyst volumes was 58% after fenestration and 74% after shunting revealing both methods to be effective. Degree of cyst volume reduction correlated significantly with clinical outcome. Patients with infratentorial cysts had more often a favourable outcome. Headache as the only symptom did not influence outcome. CONCLUSIONS: Surgery of symptomatic arachnoid cysts resulted in favourable outcome in two thirds of the patients. Both standard procedures, fenestration and shunting, are equally effective for treatment. Factors that influence outcome are the rate of volume reduction and cyst location.

Percutaneous transarticular atlantoaxial screw fixation using a cannulated screw system and image guidance.

In 2000 a cannulated screw stabilization system for posterior cervical instrumentation was introduced in our department for use in complex cervical fixation procedures. A special feature of the system is the use of thin Kirschner wires for drilling the screw paths and then placing the self-drilling, cannulated screws securely over the wires. Percutaneous application of C1-C2 transarticular screws is possible through tubes. An optional "atlas-claw" provides additional stability in cases of C1-C2 stabilization. 17 patients (10 female, 7 male, mean age 60 years) with complex cervical disorders and instability of different origin were stabilized using the Neon System (Ulrich Co., Ulm, Germany). Pathology included atlantoaxial instability based on rheumatoid arthritis (n = 12), odontoid fracture (n = 4) and os odontoideum mobile (n = 1). Computed navigation (STN 4.0, Zeiss or vector vision spine, brain lab) was used in 14 cases. Transarticular C1-C2 screw fixation was performed in 14 cases (4 patients with direct C1 massa lateralis screw fixation), craniocervical fixation (C0-C2/C3) was done in 3 patients. Percutaneous application of the C1-C2 screws was used in 7 patients. Atlas claws were applied in 8 patients. There was one medial perforation of a C2 pedicle wall and one malposition of the screw in C2 without reaching the lateral mass of C1. After a mean follow-up of 9 months there were no hardware failures and stable fusion in those cases followed after 12 months or more. Clinical results were excellent or good in 14/16 patients. Cannulated screws are an effective alternative in complex stabilization procedures of the cervical spine. The presented system is technically comfortable and allows safe percutaneous screw application as well as inclusion of computed navigation with high accuracy.