Long-term telemetric intracranial pressure monitoring for diagnosis and therapy optimisation of idiopathic intracranial hypertension.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a disease which is difficult to diagnose and moreover difficult to treat. We developed a strategy for long-term telemonitoring of intracranial pressure (ICP), by incorporation of the NEUROVENT®-P-tel System, with the goal of improved diagnosis and consequent therapy of this disease. We highlight the results obtained through this approach. METHODS: Twenty patients with suspected IIH who were treated in our hospital from August 2014 to October 2020 (16 females, 4 males, median age 36,6 years), were assigned to one of two ICP monitoring settings, "Home-Telemonitoring" (n = 12) and "Home-Monitoring" (n = 8). The ICP data were analysed and used conjointly with the accompanying clinical picture for establishment of IIH diagnosis, and telemonitoring was resumed for therapy optimisation of confirmed cases. RESULTS: The diagnosis of IIH was confirmed in 18 of the 20 patients. Various surgical/interventional treatments were applied to the confirmed cases, including ventriculoperitoneal (VP) shunting (n = 15), stenting of the transvers venous sinus (n = 1), endoscopic third ventriculostomy (ETV) (n = 1), and ETV in combination with endoscopic laser-based coagulation of the choroid Plexus (n = 1). Optimal adjustment of the implanted shunt valves was achieved with an average valve opening pressure of 6,3 ± 2,17 cm H2O for differential valves, and of 29,8 ± 3,94 cm H2O for gravitational valves. The Home-Telemonitoring setting reduced consequent outpatient visits, compared to the Home-Monitoring setting, with an average of 3,1 visits and 4,3 visits, respectively. No complications were associated with the surgical implantation of the P-tel catheter. CONCLUSION: This study offers insight into the use of long-term ICP monitoring for management of IIH patients in combination with dual-valve VP shunts. The use of NEUROVENT® P-tel system and potentially other similar fully implantable ICP-monitoring devices, albeit invasive, may be justified in this complex disease. The data suggest recommending an initial adjustment of dual-valve VP-shunts of 30 and 6 cm H2O, for gravitational and differential valves, respectively. Further research is warranted to explore potential integration of this concept in IIH management guidelines.

Home telemonitoring of intracranial pressure.

BACKGROUND: As technical progress advances, telemonitoring has become an important part of patient care in many areas of medical treatment. However, distanced surveillance of intracranial pressure (ICP) could not be established so far. With the recent introduction of a telemetric ICP measurement probe, new possibilities arise. Here, we report on a new home setup enabling home telemonitoring of intracranial pressure. METHODS: Twenty patients suffering from disturbances of cerebrospinal fluid circulation, who underwent insertion of a telemetric ICP measurement probe, were provided with medical equipment to read ICP at home and save the data on an internet-enabled computer. Training in handling the equipment was performed during in-patient stay; recorded and uploaded ICP data was then analyzed online. Therefore, the treating medical team was able to access the ICP data via a secure internet connection while telephone conferencing with the patient. RESULTS: Almost 7400 h of ICP data were recorded at home and evaluated via an internet connection according to the telemonitoring setup. This corresponds to an average record time of about 370 h per patient. ICP profiles were observed following endoscopic treatment, shunting procedures, or valve adjustments. The mean distance between the patients' residence and the consulting hospital was 172 km (range, 16-649 km). CONCLUSIONS: ICP measurements have become accessible for telemonitoring purposes. This new management of hydrocephalus reflects an alternative method in patient care, especially for those who live far away from specialized centers.

Aqueductal stenting with an intra-catheter endoscope--a technical note.

INTRODUCTION: Aqueductoplasty as well as aqueductal stenting is an accepted therapy option in short-segment aqueductal stenosis and isolated fourth ventricle. Over the years, different techniques with only slight modifications by using a conventional neuroendoscope with a working sheath to introduce different instruments have been presented. In summary, the use of Fogarty balloon catheters or flexible endoscopes to pass the narrowed aqueduct is recommended. METHODS: This technical report describes a substantially new technique for this purpose. Six patients underwent aqueductal stenting with a new intracatheter endoscope. RESULTS: Aqueductal stenting was possible in 4 out of 6 cases. No complications occurred. Handling of this new technique was good and easy without a prolonged learning curve. All four stents did work appropriately, and the procedure was considered to be successful. Of the two failures, the technique was abandoned and endoscopic third ventriculostomy (ETV) was performed in one. In the other case, suboccipital shunting was done. CONCLUSION: This technical report describes a substantially new technique for aqueductal stenting. The combination of an intracatheter miniature endoscope and a prepared ventricular catheter enables careful and elegant aqueductal stenting. Large or flexible endoscopes, balloons, or special instruments to place a stent have become completely obsolete in selected cases.

Mononostril endoscopic transsphenoidal approach to sellar and peri-sellar lesions: Personal experience and literature review.

OBJECTIVE: The endonasal endoscopic approach to skull base is still under investigation. The main goal is the minimal invasive approach to pathologies with a better rate of resection without retraction of the brain tissue. Here, the authors report their technique of transnasal endoscopic neurosurgery using a mononostril approach and its development. METHODS: The supplementary video demonstrates the different steps of the mononostril approach and resection of a pituitary adenoma. All video-recorded procedures that were carried out between 2000 and 2013 using this technique were analysed. The patients were followed prospectively. RESULTS: Visualization and handling were good in 246/251 (98%). In three cases, we had to switch to microscopy because of severe bleeding of the cavernous sinus. On follow-up, magnetic resonance imaging revealed radical tumour resection in 92% of all cases when intended. There was no mortality, and the low complication rate was remarkable. CONCLUSION: Our mononostril approach of transnasal transsphenoidal surgery shows better results compared with previously published reports in regards to radicality, low cerebrospinal fluid leaks and morbidity. The very low rate of nasal complains is particularly remarkable.

An operative technique combining endoscopic third ventriculostomy and long-term ICP monitoring.

Neuroendoscopy has been well established in the treatment of many neurological and neurosurgical diseases. Especially its application in occlusive hydrocephalus to restore a physiological cerebrospinal fluid circulation has been extensively examined in the past. Although such procedures are believed to be safe and effective, complication as well as failure rates up to 20% have been described pointing to the importance of long-term postoperative care. Therefore, different and partly invasive procedures as ventricular drain insertions or complex cranial imaging methods have been proposed; however, associated pitfalls and restrictions often limited their prognostic value and long-term benefit. An operative technique combining endoscopic third ventriculostomy and telemetric increased intracranial pressure monitoring has now been developed to optimize the postoperative care management. The main intention is to provide sufficient brain pressure data for long-term observation and early recognition of endoscopy failures and complications. The new operative technique was applied in a series with 24 patients suffering from occlusive hydrocephalus. Surgical technique and future perspectives are presented.

Clinical and radiological findings in long-term intracranial pressure monitoring.

BACKGROUND: Advantages of telemetric devices for long-term intracranial pressure (ICP) measurement have been mentioned several times in the literature. However, descriptions of associated complications are lacking. Therefore, the presented observational study focused on clinical and radiological findings after insertion of an intraparenchymal telemetric ICP monitor. METHODS: Between April 2010 and February 2013, 185 telemetric ICP catheters were implanted for diagnostic purposes. All patients were clinically followed. Radiological, microbiological and clinical data were analysed. RESULTS: One brain abscess (0.5 %) and two cutaneous infections (1.1 %) occurred in 185 patients. Staphylococcus spp. could be detected in all cases. Six patients (3.2 %) suffered from single new-onset seizures and one patient (0.5 %) from a temporary hemiparesis. Intracerebral haemorrhages occurred in 15.6 %, most of the time as small punctate bleedings. Perifocal oedematous reactions surrounding inserted telemetric catheters could be observed in 46.9 %. Multiple imaging studies revealed a tendency of complete oedema resolution over time. CONCLUSIONS: Infectious as well as haemorrhagic complication rates are well comparable with the common literature. The long-term implantation of an ICP probe does not seem to increase the risk of wound infections or brain abscess formation. Surprisingly, very high numbers of oedematous reactions after insertion of the intraparenchymal ICP monitor were seen. Reasons therefore could only be speculated upon.

Overcoming CSF overdrainage with the adjustable gravitational valve proSA.

BACKGROUND: Despite progress in shunt valve technology, CSF overdrainage is still one of the most frequent complications in shunt-treated hydrocephalus. Particularly with regard to young and adolescent patients, treatment of manifest overdrainage is complicated by several hardly influenceable factors such as increasing height and mobility. Therefore, the aim of this study was to evaluate the therapeutic efficiency of the new adjustable gravitational valve, proSA. METHODS: Sixty-four shunt-treated young hydrocephalus patients aged 1.8-41.4 years (15.5 ± 10.5 years) suffering from clinical and/or radiological overdrainage underwent shunt revision surgery with the implantation of the new proSA valve. Clinical outcome after a 1-year follow-up period, pumping function of the valve chambers as well as the number of necessary postoperative valve adjustments were examined. RESULTS: Fifty-five patients completed the study as planned. All reported a significant improvement of their clinical condition; 91 % described a complete resolution in symptoms related to overdrainage. Preoperatively, more than 85 % of the valve chambers showed no or very slow refilling with CSF. After a year of proSA treatment, more than 90 % exhibited a normal valve chamber function. During the follow-up period, a total of 136 valve adjustments were necessary. None of the proSA valves had to be surgically revised. CONCLUSIONS: The postoperative adjustability of the opening pressure level is the advantage of the new gravitational valve. The good clinical outcome is attributed to the new valve technology. The proSA appears to be a promising shunt valve to overcome overdrainage in adolescent and adult hydrocephalus patients.

Electromagnetic ventilation: first evaluation of a new method for artificial ventilation in humans.

Current methods of artificial ventilation cannot prevent diverse problems associated with mechanical ventilation. In contrast to all current forms of mechanical ventilation, electromagnetic stimulation can activate respiratory muscles directly. However, it is not known if and to what extent electromagnetic stimulation can ventilate humans. In 10 volunteers we stimulated the lateral neck using magnetic stimulators. Over 63 s we stimulated nine times with a frequency of 25 HZ for 1.1 s using 600 V, 900 V, and 1,200 V. The minimum stimulation time for each volunteer was 9 min. A Capnomac monitor measured minute ventilation. Electromagnetic stimulation was well tolerated and safe. Bilateral stimulation with 600 V achieved considerable minute ventilation (median +/- SD, 7.2 +/- 3.4 L/min) that increased at higher voltage levels (P < 0.0001). 900 V achieved sufficient minute ventilation in all volunteers (11.5 +/- 5.0 L/min; 1200 V, 14.0 +/- 4.9 L/min). This first evaluation of electromagnetic ventilation demonstrates that it can be used to ventilate humans sufficiently. This method may be developed to a new mode of ventilation.

New applicator improves waterjet dissection quality.

OBJECTIVE: Waterjet dissection is accomplished with Helix Hydro-Jet, but a new device with improved operative handling and potentially superior dissection qualities has been developed. MATERIALS AND METHODS: Eighty-four fresh cadaveric pig brains were simultaneously cut with Helix Hydro-Jet and Erbejet 2. A commonly used applicator and a new applicator for the Helix Hydro-Jet were directly compared to the new Erbejet 2. Under standardised conditions, different pressure levels were applied to the brain surface without arachnoids. Technical features, cutting depth, tissue damage and differences of applicators were examined. RESULTS: Microscopic analysis of cutting depth revealed different dissection characteristics of both the devices. With the standard applicators, waterjet cutting depth was shown to be deeper and with more foaming using the Helix Hydro-Jet compared to that of the Erbejet 2. With the new applicators, less foaming and a lower and more linear increased cutting depth were observed with the Helix Hydro-Jet, very similar to the superior qualities shown by the Erbejet 2. CONCLUSIONS: The new developed applicator of the Erbejet 2 also improves the intraoperative results of the so far applied Helix Hydro-Jet. The new Erbejet 2 provides some advantages for practicability; but in combination with the new applicator, the Helix Hydro-Jet accomplished almost identical superior dissection qualities of the Erbejet 2.

Treatment of recurrent trigeminal neuralgia due to Teflon granuloma.

Recurrent trigeminal neuralgia after microvascular decompression (MVD) may be due to insufficient decompression, dislocation of the implant to pad the neurovascular contact, or the development of granuloma. Here, we report on our experience with Teflon granuloma including its treatment and histopathological examination. In a series of 200 patients with trigeminal neuralgia MVD was performed with Teflon felt according to Jannetta's technique. In three patients with recurrent facial pain Teflon granuloma was found to be the cause for recurrence. In each instance, the granuloma was removed for histopathological examination. Mean age at the first procedure was 62.3 years and at the second procedure 66.3 years. Recurrence of pain occurred between 1 and 8.5 years after the first procedure. MRI scans demonstrated local gadolineum enhancement in the cerebellopontine angle, and CT scans showed local calcification. Intraoperatively dense fibrous tissue was found at the site of the Teflon granuloma. Histopathological examination revealed foreign body granuloma with multinuclear giant cells, collagen-rich hyalinized scar tissue, focal hemosiderin depositions, and microcalcifications. The Teflon granuloma was completely removed, and a new Teflon felt was used for re-decompression. Patients were free of pain after the second procedure at a mean of 40.3 months of follow-up. Teflon granuloma is a rare cause for recurrent facial pain after MVD. Small bleeding into the Teflon felt at surgery might trigger its development. A feasible treatment option is surgical re-exploration, nerve preserving removal of the granuloma, and repeat MVD.

The use of recombinant activated factor VII in neurosurgery.

BACKGROUND: Bleeding complications in neurosurgery often take alarming proportions without major hemodynamic effect or impairment of coagulation physiology because severe neurologic deficits are to be expected. Any measures used to stabilize or normalize coagulation are therefore of great interest. Administration of packed red cells, fresh frozen plasma, and platelet concentrates is associated with volume loading, which is suspected to multiply the secondary brain damage, for example, by the development of an edema. In this respect, the administration of rFVIIa may develop into a new option associated with low-volume administration. CASE DESCRIPTIONS: We report on 5 neurosurgical patients to whom rFVIIa was given at doses of 51 to 202 microg/kg of body weight for the treatment of severe intraoperative bleeding (n = 3) or as prophylaxis of bleeding (n = 2). The operation was completed successfully in all patients after administration of rFVIIa, with stabilization of the coagulation status. CONCLUSION: Therefore, reported cases constitute an approach in treatment and prophylaxis of bleeding complications in neurosurgery. There are reports of thromboembolic events in use of rFVIIa, particularly in unlabeled use. But according to our findings and current literature, there is no evidence of higher risk of thromboembolic adverse events in treatment with rFVIIa. However, the number of patients presented does not allow any final assessment to be made as to whether the properties of rFVIIa are of particular benefit for neurosurgical patients. Further studies with appropriate study design are required to verify effects observed in this investigation.

Solitary fibrous tumor of the foramen of Monro.

Solitary fibrous tumors have been described rarely in the central nervous system and only exceptionally within the ventricular system. This benign entity shows histoimmunochemically strong positivity for vimentin and calretinin. Little is known about the pathophysiological aspects. The authors report on a 75-year-old woman who presented with clinical signs of occlusive hydrocephalus including cognitive deficits, urine incontinence and gait disturbance. Imaging studies demonstrated a tumor at the foramen of Monro which was thought to be a colloid cyst and she underwent CSF shunting. After recurrent episodes of shunt dysfunction the tumor was removed via a transventricular approach guided by endoscopic ventriculoscopy. The histopathological examination revealed a solitary fibrous tumor. This is the first report on a solitary fibrous tumor located at the foramen of Monro in an elderly patient. Surgical removal has been considered to be the best therapeutic strategy in treating this rare entity with no need of postoperative adjuvant therapy. Further imaging and histological studies are needed to improve understanding of the pathophysiological aspects behind it.

Endoscopic-Assisted Burr Hole Reservoir and Ventricle Catheter Placement.

BACKGROUND: Accurate positioning of a ventricle catheter is of utmost importance. Various techniques to ensure optimal positioning have been described. Commonly, after catheter placement, additional manipulation is necessary to connect a burr hole reservoir or shunt components. This manipulation can lead to accidental catheter dislocation and should be avoided. Here, we present a new technique that allows direct endoscopic insertion of a burr hole reservoir with an already mounted ventricle catheter. METHODS: Before insertion, the ventricle catheter was slit at the tip, shortened to the correct length, and connected to the special burr hole reservoir. An intracatheter endoscope was then advanced through the reservoir and the connected catheter. This assemblage allowed using the endoscope as a stylet for shielded ventricular puncture. To confirm correct placement of the ventricle catheter, the endoscope was protruded a few millimeters beyond the catheter tip for inspection. RESULTS: The new technique was applied in 12 procedures. The modified burr hole reservoir was inserted for first-time ventriculoperitoneal shunting (n = 1), cerebrospinal fluid withdrawals and drug administration (n = 2), or different stenting procedures (n = 9). Optimal positioning of the catheter was achieved in 11 of 12 cases. No subcutaneous cerebrospinal fluid collection or fluid leakage through the wound occurred. No parenchymal damage or bleeding appeared. CONCLUSIONS: The use of the intracatheter endoscope combined with the modified burr hole reservoir provides a sufficient technique for accurate and safe placement. Connecting the ventricle catheter to the reservoir before the insertion reduces later manipulation and accidental dislocation of the catheter.

Telemetric Intracranial Pressure Monitoring with the Raumedic Neurovent P-tel.

BACKGROUND: Devices enabling long-term intracranial pressure monitoring have been demanded for some time. The first solutions using telemetry were proposed in 1967. Since then, many other wireless systems have followed but some technical restrictions have led to unacceptable measurement uncertainties. In 2009, a completely revised telemetric pressure device called Neurovent P-tel was introduced to the market. This report reviews technical aspects, handling, possibilities of data analysis, and the efficiency of the probe in clinical routine. METHODS: The telemetric device consists of 3 main parts: the passive implant, the active antenna, and the storage monitor. The implant with its parenchymal pressure transducer is inserted via a frontal burr hole. Pressure values can be registered with a frequency of 1 Hz or 5 Hz. Telemetrically gathered data can be viewed on the storage monitor or saved on a computer for detailed analyses. A total of 247 patients with suspected (n = 123) or known (n = 124) intracranial pressure disorders underwent insertion of the telemetric pressure probe. RESULTS: A detailed analysis of the long-term intracranial pressure profile including mean values, maximum and negative peaks, pathologic slow waves, and pulse pressure amplitudes is feasible using the detection rate of 5 Hz. This enables the verification of suspected diagnoses as normal-pressure hydrocephalus, benign intracranial hypertension, shunt malfunction, or shunt overdrainage. Long-term application also facilitates postoperative surveillance and supports valve adjustments of shunt-treated patients. CONCLUSIONS: The presented telemetric measurement system is a valuable and effective diagnostic tool in selected cases.

PROSAIKA: a prospective multicenter registry with the first programmable gravitational device for hydrocephalus shunting.

OBJECTIVE: Cerebrospinal fluid (CSF) overdrainage is a major problem in shunt therapy for hydrocephalus. The adjustable gravitational valve proSA allows for the first time a targeted compensation for overdrainage in the upright position without interfering with the differential pressure valve. To evaluate benefit, safety and reliability, the multicenter prospective registry PROSAIKA was conducted in 10 German neurosurgical centers. METHODS: Between March 2009 and July 2010, 120 hydrocephalic patients undergoing first time shunt implantation or shunt revision using proSA entered the study. 93 patients completed the 12 months follow-up. RESULTS: Hydrocephalus symptoms were improved in 86%, unchanged in 9% and deteriorated in 3%. In 51%, the proSA opening pressure was readjusted one or several times to treat suspected suboptimal shunt function, this resulted in clinical improvement in 55%, no change in 25%, and deterioration in 20% of these patients. The 1 year censored proSA shunt survival rate was 89%. Device related shunt failure was seen in two cases. CONCLUSIONS: This is the first clinical report on the implantation of the adjustable gravitational valve proSA with a follow-up of 12 months in a substantial number of patients. Irrespective of different hydrocephalus etiologies and indications for shunt surgery, the overall results after 12 months were very satisfying. The high frequency of valve readjustments underlines the fact that preoperative selection of the appropriate valve opening pressure is difficult. The low number of revisions and complications compared to other valves proves that proSA implantation adds no further risk; this valve is reliable, helpful and safe.

Electromagnetic-guided neuronavigation for safe placement of intraventricular catheters in pediatric neurosurgery.

OBJECT: Ventricular catheter shunt malfunction is the most common reason for shunt revision. Optimal ventricular catheter placement can be exceedingly difficult in patients with small ventricles or abnormal ventricular anatomy. Particularly in children and in premature infants with small head size, satisfactory positioning of the ventricular catheter can be a challenge. Navigation with electromagnetic tracking technology is an attractive and innovative therapeutic option. In this study, the authors demonstrate the advantages of using this technology for shunt placement in children. METHODS: Twenty-six children ranging in age from 4 days to 14 years (mean 3.8 years) with hydrocephalus and difficult ventricular anatomy or slit ventricles underwent electromagnetic-guided neuronavigated intraventricular catheter placement in a total of 29 procedures. RESULTS: The single-coil technology allows one to use flexible instruments, in this case the ventricular catheter stylet, to be tracked at the tip. Head movement during the operative procedure is possible without loss of navigation precision. The intraoperative catheter placement documented by screenshots correlated exactly with the position on the postoperative CT scan. There was no need for repeated ventricular punctures. There were no operative complications. Postoperatively, all children had accurate shunt placement. The overall shunt failure rate in our group was 15%, including 3 shunt infections (after 1 month, 5 months, and 10 months) requiring operative revision and 1 distal shunt failure. There were no proximal shunt malfunctions during follow-up (mean 23.5 months). CONCLUSIONS: The electromagnetic-guided neuronavigation system enables safe and optimal catheter placement, especially in children and premature infants, alleviating the need for repeated cannulation attempts for ventricular puncture. In contrast to stereotactic techniques and conventional neuronavigation, there is no need for sharp head fixation using a Mayfield clamp. This technique may present the possibility of reducing proximal shunt failure rates and costs for hydrocephalus treatment in this age cohort.

First clinical results with a new telemetric intracranial pressure-monitoring system.

BACKGROUND: The knowledge of intracranial pressure (ICP) is the basis of an appropriate neurosurgical treatment. Because clinical, fundoscopic, or radiological data alone are often elusive, a pre- or postoperative long-term monitoring of the ICP itself is desirable. OBJECTIVE: We describe the first clinical experiences with a new telemetric ICP-monitoring device. METHODS: The transducer of this telemetric intraparenchymal pressure probe is placed under the galea over the calvaria. ICP can be monitored via a special telemetric reader, placed over the intact skin, and the ICP values are stored in a small portable computer. The system does not require an intensive care environment and can be used in any ward or even at home. The system was successfully applied in 10 patients (age, 3-56 years) in whom raised ICP due to hydrocephalus, shunt dysfunction, endoscopic third ventriculostomy failure, craniostenosis, or pseudotumor cerebri was suspected. RESULTS: Continuous telemetric monitoring of ICP was performed for 2 to 24 weeks. In 7 patients, increased ICP values could be excluded, and further surgical maneuvers were avoided. In 3 patients, repeated plateaus or continuously raised ICP indicated surgery resulting in a normalization of ICP. CONCLUSION: This new telemetric system was safe and effective for ICP measurement over a long period, including home monitoring. For the patients, it was easy to handle, and reliable data could be recorded over many weeks. Based on this preliminary experience, the authors consider the new system extremely advantageous in surgical decision making in particularly difficult cases of suspected abnormalities of ICP.

Safety and efficacy of microporous polysaccharide hemospheres in neurosurgery.

BACKGROUND: Effective hemostasis is mandatory for brain tumor surgery. Microporous polysaccharide hemosphere (MPH) powder, a white powder compounded from potato starch, was recently introduced for surgical and emergency application. OBJECTIVE: To evaluate the safety and efficacy of MPHs in brain tumor surgery. METHODS: Thirty-three patients (mean age, 58 years; range, 22-84 years) underwent microsurgical brain tumor resection. Final hemostasis was performed by topical application of MPHs, video recorded, and subsequently analyzed. Blood samples were taken before surgery, before application of hemospheres, and postoperatively. Volume measurements of the tumor, resection cavity, and postoperative hematoma were done on magnetic resonance imaging and computed tomography scans. Clinical examinations focused on neurological outcome, complications, and allergic reactions. RESULTS: Effective hemostasis was achieved by exclusive use of MPHs in 32 patients. In 1 patient, a single arterial bleeding underwent additional bipolar electrocauterization. Mean operative time was 156.8 minutes (range, 60-235 minutes). Hemostasis with MPHs required 57 seconds (mean; range, 8-202 seconds). Subjective neurosurgeons' ranking of the hemostasis effect indicated excellent satisfaction. For the first 3 months, there was no hemospheres-related postoperative neurological worsening, no signs of allergic reaction, and no embolic complications. Early postoperative and 3-month follow-up magnetic resonance imaging and computed tomography scans excluded any expansive bleeding complication. As early as postoperative day 1, MPHs were no longer detected. There was no tumor mimicking contrast enhancement. CONCLUSION: In neurosurgery, MPHs allow fast and effective minimally invasive hemostasis. In this small case series, no adverse reactions were found.

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.

Waterjet dissection in pediatric cranioplasty.

OBJECT: Waterjet dissection has been shown to separate tissues of different resistance, with preservation of blood vessels. In cranioplasty, separation of subcutaneous tissue and dura mater is often difficult to achieve because the various tissue layers strongly adhere to each other after decompressive craniotomy. In the present study, the potential advantages and drawbacks of the waterjet technique in cranioplasty after craniectomy and duraplasty are addressed. METHODS: The waterjet effect on fresh human cadaveric dura mater specimens as well as on several dural repair patches was tested in vitro under standardized conditions, with waterjet pressures up to 80 bar. Subsequently, 8 pediatric patients (5 boys, 3 girls; mean age 9.9 years, range 1.2-16.7 years) who had been subjected to decompressive craniectomy (7 with duraplasty including bovine pericardium as a dural substitute, 1 without duraplasty in congenital craniosynostosis) underwent waterjet cranioplasty. The waterjet was used to separate the galea and the dura mater. The technique was applied tangentially between the dura and the galea, with different pressure levels up to 50 bar. RESULTS: In vitro, fresh cadaveric human dura mater as well as 2 different dural repair substitutes showed a very high resistance to waterjet dissection up to 80 bar. The human dura and the various substitutes were dissected only after long-lasting exposure to the waterjet. Human dura was perforated at pressures of 60 bar and higher. Bovine pericardium dural substitute was perforated at pressures of 55 bar and higher. Artificial nonabsorbable polyesterurethane dural substitute was dissected at pressures of 60 bar and higher. In the clinical setting, the waterjet was able to separate galea and dura with minimal bleeding. No blood transfusion was required. Dissection of scarred tissue was possible by a waterjet of 40 bar pressure. Tissue layers were stretched and separated by the waterjet dissection, and a very reliable hemostasis resulted. This resulted in an effective reduction of bleeding, with < 60 ml blood loss in 7 of the 8 cases. Neither a dural tear nor a perforation of any duraplasty occurred during operative preparation. There were no operative or postoperative complications. CONCLUSIONS: The experimental and clinical data show that waterjet separation of dura mater, dural substitute, and galea can be performed with a high level of safety to avoid dural tears. The waterjet dissection stretches tissue layers, which results in a reliable hemostasis effect. This potentially results in an effective reduction of surgical blood loss, which should be the focus of further studies.