Does granulocyte-colony stimulating factor stimulate peripheral nerve regeneration? An experimental study on traumatic lesion of the sciatic nerve in rats.

AIM OF THE STUDY: To analyse the therapeutic potential of granulocyte-colony stimulating factor (G-CSF) treatment using a rat model of traumatic sciatic nerve lesion. CLINICAL RATIONALE FOR THE STUDY: G-CSF has proven strong neurotrophic properties in various models of ischaemic and traumatic brain injury. Fewer studies exist regarding the influence of G-CSF on posttraumatic peripheral nerve regeneration. Currently, the possibilities of pharmacological prevention or treatment of mechanical nerve injury are limited, and there is an urgent need to find new treatment strategies applicable in clinical situations. MATERIAL AND METHODS: A controlled traumatic right sciatic nerve lesion was set using a waterjet device. Three treatment groups were created. In the first group, G-CSF was administered after sciatic nerve injury. The second group received G-CSF before and after trauma, while the third group was treated with glucose 5%-solution. Sciatic nerve function was assessed clinically and electrophysiologically at day 1, and after weeks 1, 2, 4 and 6. Additionally, α-motoneurons of the spinal cord and sciatic nerve fibres were counted at week 6. RESULTS: Clinically, rats in both G-CSF groups improved faster compared to the control group. Additionally, animals treated with G-CSF had a significantly better improvement of motor potential amplitude and motor nerve conduction velocity at week 6 (p < 0.05). Histologically, G-CSF treatment resulted in a significantly higher number of α-motoneurons and small myelinated nerve fibres compared to placebo treatment (p < 0.05). CONCLUSIONS AND CLINICAL IMPLICATIONS: Under G-CSF treatment, the recovery of motor nerve conduction velocity and amplitude was enhanced. Further, signs of nerve regeneration and preservation of α-motoneurons were observed. These results indicate that G-CSF might accelerate and intensify the recovery of injured nerves. Thus, treatment with G-CSF may be beneficial for patients with peripheral nerve damage, and should be explored in further clinical studies.

Resection of C6 gliomas in rats with the aid of the waterjet technique.

OBJECTIVES: While clinically the safety and efficacy of waterjet resection of brain tumors have been shown, evidence that waterjet dissection improves tumor resection radicality in comparison with conventional techniques is still missing. In the present study, resection radicality and tumor-free long-term survival of both techniques were evaluated in a C6-glioma model. MATERIAL AND METHODS: Fifty-thousand C6-glioma cells were stereotactically transplanted in the left frontal lobe of 100 male Sprague-Dawley rats. After MRI-scanning for evaluation of tumor extension, microsurgical tumor resection was performed with conventional techniques (n=50) or with the waterjet dissector at pressures of 6bar (n=50). Twenty-five animals of each group were sacrificed after surgery for histological analysis. For analysis of survival after tumor resection, twenty-five animals of each group were followed-up to analyze tumor-free survival using the Kaplan Meier method. RESULTS: In the waterjet group, the resection cavity was free of C6-tumor cells in 10/25 (40%) rats showing a trend (p=0.3) towards better resection radicality compared to the rats that were treated conventionally (7/10; 28%). R1-resection with up to 250C6 cells/object slice was found in 14/25 (56%) rats after waterjet dissection compared to 6/25 (24%) rats treated conventionally showing significance (p<0.01). Probability of survival was 38% after 2 weeks and 20% after 6 months in the waterjet group compared to 30% and 16% respectively in the conventional group. Diffuse tumor cell spreading with possible influence on survival was shown in 47/50 rats. CONCLUSION: In this experimental model, waterjet tumor resection did reveal significantly better resection radicality compared to the conventional technique. Although a direct transfer of these results to human glioma surgery is prohibited, the waterjet technique might contribute to the best possible resection radicality in human gliomas. Nevertheless, tumor cell spreading remains a major problem. Further studies have to address that the surgical results - in deed - improve the postoperative outcome.

Remarks upon the term stereotaxy: a linguistic and historical note.

The correct explanation of the term 'stereotaxy' is linguistically not self-evident because the Greek term stereon means not spatial but 'hard' or 'solid'. The aim of our study was to clarify the term stereotaxy historically and linguistically. We carried out our study by reviewing the neurosurgical and ancient Greek literature. The term stereotaxy is composed of two ancient Greek words: stereon and taxis. Stereon was used in particular as a technical term for geometrical solids in Greek mathematics. This term can be traced back to Platon and Euclid in the 4th and 3rd century BC, respectively. Only in this sense of the word does stereon in stereotaxy actually mean 'spatial' or '3-dimensional'. Taxis is derived from the verb tattein(τάττειν) with the meaning 'to position'. The terms 'stereotaxis' and 'stereotaxic apparatus' were introduced by Clarke and Horsley in 1908 to denote a method for the precise positioning of electrodes into the deep cerebellar nuclei of apes. The target in space was defined by 3 distances in relation to 3 orthogonal planes. Although this concept corresponded exactly to x-, y- and z-coordinates in a cartesian coordinate system, Clarke never used the concept of coordinates. The intuitive explanation of the term stereotaxy as spatial positioning is correct, but linguistically more complex than would be expected.

Towards a glioma model for surgical technique evaluation in the rat.

INTRODUCTION: Evaluation of new surgical techniques in animal models is frequently challenging. This article describes the pitfalls, peculiarities and the final best applicable model for evaluating surgical techniques for glioma resection. METHODS: The C6 glioma cell line and the Sprague-Dawley rat strain were selected. Fifty-thousand glioma cells were stereotactically transplanted in the left hemisphere of 137 male adult rats. Evaluation of solid tumour formation, tumour growth and scheduling of surgical resection was performed by MR scanning at 1, 2, and 4 weeks after transplantation and 3 and 6 months after tumour resection. Microsurgical tumour resection was performed with conventional techniques or with the waterjet dissector at a pressure of 6 bar. One subgroup of each surgical technique was sacrificed directly after surgery for histological analysis. The other subgroup was followed up for long-term analysis. RESULTS: The transplantation site was of great importance. After transplantation of tumour cells posterior to the bregma, intra-ventricular tumour growth with spreading occurred. Homogenous and reproducible tumour growth was achieved after grafting cells lateral - 3 mm, anterior + 1 mm, and - 2.5 mm ventral to the bregma. After development of solid tumours on MR imaging, animals were subjected to surgery. MR and intra-operative findings corresponded well. However, MRI and intra-operative none-detectable perivascular tumour spreading was histologically observed in the majority of cases. CONCLUSIONS: The presented glioma rat model consisting of the C6 cell line and Sprague-Dawley rats as recipients is a well-suited model to investigate surgical techniques and their impact on tumour therapy. However, the site of transplantation, the preparation of cell grafts and the technique of tumour growth evaluation is of utmost importance to achieve reliable results.

Endoscopic third ventriculostomy: preoperative considerations and intraoperative strategy based on 300 procedures.

PURPOSE: Although successful endoscopic third ventriculostomy (ETV) has been reported for many indications, peculiarities of the surgical technique in each separate indication require particular respect. METHODS: A detailed account of the authors' surgical technique, their presurgical considerations, and their intraoperative strategies to perform ETV is presented. Surgery of representative obstructive hydrocephalus cases in posterior fossa lesions (cerebellar infarction, posterior fossa tumor), in distortion of the ventricular system (intracranial hemorrhage, basilar artery aneurysm) and in membranous obstruction (aqueductal stenosis, posterior fossa malformation), is illustrated in detail. RESULTS: In posterior fossa lesions, careful evaluation of the prepontine space and localization of the basilar artery is mandatory. Recognition of mammillary bodies and infundibular recess is of particular importance since the third ventricle floor is rather thick and nontranslucent. In distortion of the ventricular system, careful analysis of the preoperative imaging allows the selection of the optimal approach. Sometimes, blood clot removal and vigorous irrigation is required. Frequently, the landmarks are difficult to identify. These are cases for experienced endoscopic neurosurgeons. In aqueductal stenosis and posterior fossa malformation, perforation of the often thin and translucent ventricular floor is easy because of clear anatomical landmarks. Those are ideal candidates for ETV. For experienced neuroendoscopists, the authors advocate inspection of the fourth ventricle with a flexible scope to ensure cerebrospinal fluid (CSF) circulation obstruction. CONCLUSIONS: ETV is a frequent and well-established endoscopic technique. Based on the underlying pathology, the technique has to be modified to obtain good results with minimal complications.

Anterior interosseous nerve compression syndrome: is there a role for endoscopy?

BACKGROUND: Anterior interosseous nerve syndrome is characterized by paralysis of the flexor digitorum profundus, the flexor pollicis longus and the pronator quadratus muscles without sensory loss. Extended exploration of the anterior interosseous nerve is the surgical treatment of choice. The present study evaluates the feasibility of an endoscopic approach for nerve decompression. METHODS: Preparation of the anterior interosseous nerve was performed in ten human cadaver arms. Subsequently, one female patient suffering from anterior interosseous nerve syndrome was endoscopically operated on. FINDINGS: A skin incision of 3-4 cm in the proximal direction was made at the forearm, and the median nerve was visualized between the pronator teres muscle and the flexor digitorum superficialis. Subsequently, the anterior interosseus nerve branch was identified, followed distally and decompressed under endoscopic view. The procedure could be accomplished in all cases under endoscopic view. Due to the very steep surgical angle, a branch of the anterior interosseus nerve was injured in one cadaver case. In all other cases, no adverse effects were observed. In the clinical case, the anterior interosseus nerve was endoscopically identified and decompressed, but a skin incision of 5 cm was required. CONCLUSIONS: The results demonstrate that an endoscopic decompression of the anterior interosseus nerve is possible. Several difficulties occurred: Due to the depth of the surgical approach, especially in case of bulky muscles and very small skin incisions, the view is limited, harboring a higher risk of nerve injury. With more experience and specially designed endoscopes, application of this technique in anterior interosseus nerve compression syndrome might become more feasible.

Water jet dissection in neurosurgery: an update after 208 procedures with special reference to surgical technique and complications.

BACKGROUND: Water jet dissection represents a promising technique for precise brain tissue dissection with preservation of blood vessels. In the past, the water jet dissector has been used for various pathologies. A detailed report of the surgical technique is lacking. OBJECTIVE: The authors present their results after 208 procedures with a special focus on surgical technique, intraoperative suitability, advantages, and disadvantages. METHODS: Between March 1997 and April 2009, 208 patients with various intracranial neurosurgical pathologies were operated on with the water jet dissector. Handling of the device and its usefulness and extent of application were assessed. The pressures encountered, potential risks, and complications were documented. The patients were followed 1 to 24 months postoperatively. RESULTS: A detailed presentation of the surgical technique is given. Differences and limitations of the water jet dissection device in the various pathologies were evaluated. The water jet dissector was intensively used in 127 procedures (61.1%), intermittently used in 56 procedures (26.9%), and scarcely used in 25 procedures (12%). The device was considered to be very helpful in 166 procedures (79.8%) and helpful to some extent in 33 procedures (15.9%). In 8 (3.8%) procedures, it was not helpful, and in 1 procedure (0.5%), the usefulness was not documented by the surgeon. CONCLUSION: The water jet dissector can be applied easily and very safely. Precise tissue dissection with preservation of blood vessels and no greater risk of complications are possible. However, the clinical consequences of the described qualities need to be demonstrated in a randomized clinical trial.

Waterjet dissection of peripheral nerves: an experimental study of the sciatic nerve of rats.

BACKGROUND: Although waterjet dissection has been well evaluated in intracranial pathologies, little is known of its qualities in peripheral nerve surgery. Theoretically, the precise dissection qualities could support the separation of nerves from adjacent tissues and improve the preservation of nerve integrity in peripheral nerve surgery. OBJECTIVE: To evaluate the potential of the new waterjet dissector in peripheral nerve surgery. METHODS: Waterjet dissection with pressures of 20 to 80 bar was applied on the sciatic nerves of 101 rats. The effect of waterjet dissection on the sciatic nerve was evaluated by clinical tests, neurophysiological examinations, and histopathological studies up to 12 weeks after surgery. RESULTS: With waterjet pressures up to 30 bar, the sciatic nerve was preserved in its integrity in all cases. Functional damaging was observed at pressures of 40 bar and higher. However, all but 1 rat in the 80 bar subgroup showed complete functional regeneration at 12 weeks after surgery. Histopathologically, small water bubbles were observed around the nerves. At 40 bar and higher, the sciatic nerves showed signs of direct nerve injury. However, all these animals showed nerve regeneration after 12 weeks, as demonstrated by histological studies. CONCLUSION: Sciatic nerves were preserved functionally and morphologically at pressures up to 30 bar. Between 40 and 80 bar, reliable functional and morphological nerve regeneration occurred. Waterjet pressures up to 30 bar might be applied safely under clinical conditions. This technique might be well suited to separate intact peripheral nerves from adjacent tumor or scar tissue. Further studies will have to show the clinical relevance of these dissection qualities.

Simple endoscopic decompression of cubital tunnel syndrome with the Agee system: anatomic study and first clinical results.

BACKGROUND: Simple decompression in ulnar nerve compression syndromes offers options for endoscopic applications. OBJECTIVE: The authors present their initial experience with the Agee device. PATIENTS AND METHODS: The monoportal endoscopic technique (Agee system) was evaluated on 10 cadaveric arms. Subsequently, 32 arms of 29 patients were operated on between January 2006 and March 2009. All patients presented with typical clinical signs and neurophysiologic studies. Long-term follow-up examinations were obtained in 27 of 32 arms. RESULTS: In the cadaver study, the ulnar nerve was always correctly identified. No nerve damage occurred, and sufficient decompression of the ulnar nerve was always achieved. In the clinical series, no intraoperative complications were observed. A change to open technique was not required, and no worsening of the cubital tunnel syndrome occurred. Two wound infections required surgical wound cleaning. Wound hematomas treated conservatively were found in 5 cases. On long-term follow-up, an improvement in the McGowan- Classification was achieved in 22 of 27 cases. One patient was operated on by open surgery after endoscopic surgery. CONCLUSION: The endoscopic technique for ulnar nerve entrapment syndrome using an Agee device appears to be safe and efficient. The results are comparable to those achieved with simple open decompression. A randomized prospective study should be performed to further evaluate the value of new technique in ulnar nerve entrapment syndrome.

Endoscopic decompression of the ulnar nerve at the elbow.

OBJECTIVE: Recently, several studies suggested that simple decompression is as effective as anterior transposition in ulnar nerve entrapment syndrome. Simple decompression might be performed with minimally invasive techniques. The authors present their technique and results with endoscopic decompression in ulnar nerve entrapment syndrome. MATERIAL AND METHODS: Between January 2005 and March 2008, 24 patients (mean age, 45.5 years; range, 26-67 years) underwent surgery for 26 ulnar nerve entrapment syndromes (2 bilateral). All patients presented with typical clinical signs and neurophysiologic studies. RESULTS: Intraoperatively, the ulnar nerve was localized directly at the sulcus, and subsequently under endoscopic view, the decompression was completed approximately 10 cm proximal as well as distal. In 26 cases, a significant compression of the nerve was found directly at and distal to the sulcus. In 1 case, a subluxation of the nerve was observed, the endoscopic technique was abandoned, and open anterior submuscular transposition followed. The procedure was successful in 19 of 22 cases (86%). Neither intraoperative nor postoperative complications were observed. Nevertheless, the identification of the nerve directly at the sulcus, where severe nerve compression was often found, seemed to be difficult and potentially risky, particularly in obese patients. CONCLUSION: The endoscopic technique for ulnar nerve entrapment syndrome seems to be safe and effective. However, particularly in patients with a thick subcutaneous fat layer, identification of the nerve at the sulcus is difficult and possible more risky than in open simple decompression. A randomized prospective study should be performed to further evaluate the value of this new technique in the treatment of ulnar nerve entrapment syndrome.

Long-term follow-up of dual-portal endoscopic release of the transverse ligament in carpal tunnel syndrome: an analysis of 94 cases.

OBJECTIVE: The long-term efficacy of dual-portal endoscopic release of the transverse ligament in carpal tunnel syndrome is still being debated. In this study, the authors present 94 endoscopic carpal tunnel surgery cases with long-term follow-up data. METHODS: The study includes 72 patients aged 17 to 86 years (mean age, 53.4 years); bilateral surgery was performed in 22 of these patients. Seventy-two hands of female patients and 22 hands of male patients were included. All procedures were performed with a dual-portal set according to the Chow technique. All patients were examined 2 to 3 months after surgery. The long-term follow-up evaluation was based on telephone interviews 5 to 12 years (mean, 8.2 years) after surgery. RESULTS: From a cohort of 214 cases that were treated surgically between 1995 and 2002, 94 cases (44%) could be evaluated for long-term follow-up. Four of these patients had to be excluded from long-term follow-up because of a switch to an open technique and early open revision (3-6 months after the first surgery), owing to persistent symptoms. A good to optimal postoperative outcome with improvement of neurological signs and subjective patient satisfaction was observed in 84 (93.3%) of the remaining 90 cases. There were no recurrences. CONCLUSION: The study shows that dual-portal endoscopic release of the transverse ligament in carpal tunnel syndrome is a valuable technique that produces very good long-term results and high patient satisfaction and does not result in a significant recurrence rate.