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Since the beginnings of medicine, physicians have sought minimally invasive ways to peer into body cavities. It is only in the last several decades that the promises of endoscopy have begun to be answered. What follows is a brief outline of the development of endoscopic technology and its application to the nervous system both for diagnostic and therapeutic procedures.
In sum, understanding some of the basic principles of endoscopy and awareness of available resources can potentially be of considerable help to experienced neurosurgeons as well as beginners in selection of the most appropriate tools for different procedures and making cost-effective choices when browsing through multiple commercial advertisements and purchasing new equipment. Although numerous advantages in science and industry have made it possible to offer a wide variety of neuroendoscopes and tools, we believe the major achievements in this field are yet to occur. This particularly refers to the development of smaller fiberoptic scopes with better image quality and three-dimensional endoscopes and to the invention of more efficient tools for endoscopic tumor removal with the same degree of safety as in open surgery.
Optical coherence tomography (OCT) is a non-invasive and non-contact imaging technology that has been applied to several biomedical applications. We have recently demonstrated that OCT allows discrimination of tumor adjacent brain, diffuse and solid tumor tissue and that this technology may be used to detect residual tumor within the resection cavity during resection of intrinsic brain tumors. Here we show that an OCT integrated endoscope can image the endoventricular anatomy and other endoscopically accessible structures in a human brain specimen. A Sirius 713 optical coherence tomography device was mounted to a modified rigid endoscope. A formalin-fixed human brain specimen was used to simulate endoscopic visualization of brain anatomy and two specimens of fixed malignant tumors with endoventricular growth patterns. Simultaneous OCT imaging and endoscopic video imaging of the visible spectrum was possible using a graded index rod endoscope. OCT imaging of a human brain specimen in water allowed an in-depth view into structures like the walls of the ventricular system, the choroid plexus or the thalamostriatal vein. OCT further allowed imaging of structures beyond tissue barriers or opaque media. In this fixed specimen OCT allowed discrimination of vascular structures down to a diameter of 50 mum. In vessels larger that 100 mum the lumen could be discriminated and within larger blood vessels a layered structure of the vascular wall as well as endovascular plaques could be visualized. This in vitro pilot study has demonstrated that OCT integrated into neuroendoscopes may add information that cannot be obtained by the video imaging alone. This technology may provide an extra margin of safety by providing cross-sectional images of tissue barriers within optically opaque conditions.
BACKGROUND: During an endoscopic neurosurgical procedure a sudden increase in intracranial pressure may occur at any time. We present a prospective study of haemodynamic changes during such procedures. METHODS: Physiological data were recorded during the whole operative procedure in 17 consecutive patients who underwent an endoscopic neurosurgical procedure under general anaesthesia. Monitoring included invasive blood pressure, intracranial pressure, electrocardiogram, end-expired carbon dioxide, pulse oximetry and heart rate. Pressure and ECG waveforms were recorded at 100 Hz and evaluated in a subsequent offline analysis. RESULTS: In almost every case, the occurrence of hypertension and tachycardia was clearly the result of an increase in intracranial pressure. Also, a Cushing reflex developed in almost every case where the cerebral perfusion pressure dropped below 15 mm Hg. The occurrence of bradycardia was not systematically associated with a low cerebral perfusion pressure. CONCLUSION: In this study, we describe the haemodynamic effects of increased intracranial pressure during endoscopic neurosurgical procedures and their respective sequence of events at high temporal resolution. Although most clinicians rely on the occurrence of bradycardia to diagnose intracranial hypertension during endoscopic neurosurgical procedures, we show that a simultaneous onset of hypertension and tachycardia is a better indicator of impaired brain perfusion. Waiting for a persistent bradycardia to alert the surgeon during endoscopic neurosurgical procedures could allow severe bradycardia or even asystole to develop.
BACKGROUND: Intraventricular haemorrhages (IVHs) caused by bleeding aneurysms are critical conditions that often carry a severe prognosis. Two main problems must be urgently dealt with: the secondary damage caused by intraventricular clotting and the risk of early rebleeding. A protocol of ultra-early endoscopic ventricular evacuation, after securing the aneurysm with coils, is proposed to solve this challenge in the acute phase and within a few hours of onset. METHODS: Ten consecutive patients presenting with haematocephalus from aneurysm rupture were treated in our institute with coiling and endoscopic clot aspiration extended to the whole ventricular system. The only inclusion criteria were the presence of a massive IVH and an aneurysm appropriate for coiling. Computed tomography scans obtained before (within 4 h of symptom onset in all patients) and immediately after surgery were compared for Graeb score and ventriculocranial ratio (VCR); the Glasgow Outcome Scale (GOS) was assessed at 1 year. RESULT: All patients were treated within 2 days of onset. The procedure resulted in a mean 58% removal of ventricular blood and decrease of hydrocephalus; the mean (standard deviation (SD)) Graeb score reduced from 11.5 (0.7) to 4.7 (2.2) (p<0.001) and mean ventriculocranial ratio from 0.26 (0.06) to 0.17 (0.05) (p<0.001). No rebleeding or delayed hydrocephalus needing shunt was observed. Mortality at 1 year was 30%; marked disability (GOS = 3) and good recovery (GOS = 5) were observed in 40% and 30% of patients, respectively. CONCLUSIONS: Early neuroendoscopic removal of blood casting from the lateral to the fourth ventricle after coiling of bleeding aneurysms is a feasible approach, allowing in most instances the rapid improvement of the IVH.
Treatment strategies for CNS germinoma are currently evolving. Current approaches include reducing the volume and dose of radiation by adding pre-irradiation chemotherapy. Very accurate staging is necessary with such an approach to prevent failures. Eight consecutive patients with pineal germinoma at one institution underwent endoscopic surgery for tumor biopsy, direct visualization of the third ventricular region, and third ventriculostomy for those with hydrocephalus. All patients were treated with 4 cycles of chemotherapy. Conformal field radiation therapy followed, with the dose to the tumor bed dependent on the response to chemotherapy. Patients who had MRI, endoscopic, or cerebrospinal fluid evidence of multicentric or disseminated disease also received craniospinal radiation. Six patients had diabetes insipidus (DI) at presentation. All 6 had tumor studding the floor of the third ventricle on endoscopic visualization, while only 4 of those patients had MRI evidence of disease in that region. All patients have completed therapy and are alive, with no evidence of disease at median follow-up of 31.5 months from diagnosis. Direct endoscopic visualization of the third ventricular region may be more sensitive than MRI for evaluating the presence of suprasellar disease and appears to add important information. This parameter should be added to the staging evaluation when feasible. In this series, the presence of DI was 100% predictive of suprasellar disease, even when the MRI was negative for involvement of that region. Patients should be evaluated for DI as part of the initial staging, and if it is present, the patients should be treated for suprasellar disease regardless of MRI findings.
A 22-year-old woman presented with a rare case of multiple epidermoid cysts located in the pineal and extracranial regions. Magnetic resonance (MR) imaging showed a lesion in the pineal region as hypointense on the T(1)-weighted image and hyperintense on the T(2)-weighted image, without enhancement. Neuroendoscopic treatment was performed under a diagnosis of pineal cyst. However, the cyst wall was too thick to perforate, although third ventriculostomy was performed. Diffusion-weighted MR imaging demonstrated the lesions in the pineal and extracranial regions as marked hyperintensity. The diagnosis was epidermoid cyst. Subsequently, neuroendoscopic treatment of the pineal epidermoid cyst was performed. Careful preoperative diagnosis of epidermoid cysts based on diffusion-weighted MR imaging is required.
OBJECTIVE: To evaluate the clinical use of a head-mounted display (HMD) for visualization in all neuroendoscopic procedures. MATERIALS AND METHODS: We retrospectively evaluated all endoscopic and endoscope-controlled procedures in which the HMD was used in our department between July 1999 and June 2002. RESULTS: A total of 269 endoscopic procedures were performed. In 147 cases intraventricular endoscopic procedures were carried out, mostly third ventriculocisternostomies, for which a fiberscope was used exclusively. Thirty intracranial cysts were fenestrated or removed (colloid cysts) with the help of various endoscopes. A total of 87 endoscopic transsphenoidal surgeries were performed with a lensscope. In only one case was it necessary to abandon use of the HMD due to inferior visualization; in all other cases visualization by the HMD was thought to be sufficient. Fatigue of the surgeon due to wearing the helmet did not occur. All surgeons had the impression that visual strain was decreased in comparison to looking at a monitor from a distance. The working position was considered to be more comfortable when wearing the HMD, and eye-hand coordination was improved. No technical problems occurred with the system. CONCLUSIONS: The HMD is a new visualization tool in neurosurgery that may improve the ergonomics of neuroendoscopic and endoscope-controlled procedures.
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A new method of direct endoscopy of the subarachnoid space and a major part of the ventricles of the human central nervous system is presented. The technique was developed on more than 100 human bodies with the help of a bronchoscope. Percutaneous entry into the subarachnoidal space is performed from the dorsal side between vertebrae L5 and S1. The endoscope can be moved along the spinal cord on both the dorsal and the ventral side. From the dorsal side of spinal cord the cerebello-medullary cistern can be reached. The fourth ventricle is entered through the median aperture and then the third ventricle through the cerebral aqueduct. From the ventral side of the spinal cord the posterior cranial fossa is reached and the large arteries and the cranial nerves can be inspected. The main conclusion of the present report is that the subarachnoid space seems to be large enough for a coaxial exploration with a 3-5 mm diameter fibroscope if the investigator possesses a good knowledge of the subarachnoid anatomy. The technique provides new approaches in research and possibilities of clinical investigations and therapy.
As part of a series of essays about the first 25 years of the International Society for Pediatric Neurosurgery--what we have accomplished and where we have been--I have decided to turn my attention to where we are now and where we are going. A corollary to consider, perhaps, is where we should be going. In other words, what is the appropriate relationship between pediatric neurosurgery and general neurosurgery?
The population born prematurely is particularly prone to hydrocephalus. Shunting techniques, whilst still the gold standard, have considerable failure rates and contribute significant morbidity and mortality. The role of neuroendoscopic techniques in the treatment of such patients is explored, and a series of 19 patients born prematurely and operated on neuroendoscopically before their 1st birthdays is described.
Four patients harbouring a colloid cyst of the 3rd ventricle were operated on endoscopically. With the "classical" monoportal technique, through a precoronal burr hole only partial removal could be achieved in the first case. As the crucial point of the procedure is the safe dissection of the cyst from the thela chorioidea and from the internal cerebral veins, adequate control of the posterior rim of the foramen of Monro and the roof of the 3rd ventricle is mandatory. Accordingly in other three cases a CT-guided biportal endoscopic technique was applied, which permitted radical removal of the entire cyst with maximum safety. CT-guidance is essential for optimal planning after careful study of the individual anatomy. In this way the rigid scopes are moved exclusively along their own axes throughout the procedure, the resulting brain damage thereby being minimal. With regard to all circumstances of the procedure, the use of flexible endoscopes appears to be inappropriate and biportal endoscopy offers itself as the method of choice.
Third ventriculostomy has become an increasing popular procedure for the treatment of hydrocephalus of different aetiologies. Between october 1997 and october 1998, 17 patients (12 females, 5 males; 12-82 year-old; mean age 43) underwent image-assisted endoscopic third ventriculostomy for hydrocephalus at the Istituto Nazionale Neurologico "C.Besta" of Milano. There was no mortality and no long term morbidity. Neuronavigation has been found useful in selecting the safest trajectory to the target avoiding any traction on the foramen of Monro related structures and allowing the necessary mobility for fine adjustments under visual and "tactile" control when choosing the safest point to perform the stoma. According to our experience neuro-endoscopy and neuronavigation seems to be complementary in reaching easy, safe and successful results in the treatment of hydrocephalus of different origins.
The authors describe a technique for the initial management of patients with pineal region neoplams and symptomatic hydrocephalus. Endoscopic third ventriculostomy and, if possible, tumor biopsy are performed through a single precoronal burr hole. When indicated, formal tumor resection can be performed nonemergently, without the need for ventricular drainage or shunting.
Neuroendoscopic treatment of hydrocephalic children is an established surgical modality. Open magnetic resonance imaging (MRI) technology introduces new imaging features that, in combination with endoscopy, seem particularly valuable for performing these operations. "Near" real-time production of MR images in 3 dimensions during the procedure allows real-time neuronavigation, thus, facilitating guidance of an endoscope. Additionally, intraoperative changes such as brain shift, effects of perforation, and drainage of cysts are shown during an ongoing procedure. The patency of cysts or fluid compartments inside the ventricular system can be controlled by intraoperative injection of diluted gadolinium into the cystic compartments. These new therapeutic options were applied in 2 hydrocephalic children with complex ventricular cysts: a 3-month-old girl with a large, septated arachnoidal cyst and internal hydrocephalus and a boy of 7 years, 2 months with congenital hydrocephalus and premature closure of the coronary sutures.
This report describes the clinical application of an ultrasonic aspirator for endoscopic neurosurgery. Eight patients with intraventricular hematoma with complete tamponade of the ventricular system and marked hydrocephalus were treated with the ultrasonic aspirator for endoscopic neurosurgery. Clinical evaluation and neuroimaging studies were obtained for one month. Removal of hematoma was confirmed on follow-up imaging. The ultrasonic aspirator is operated by electrostriction transducer on low generating power (15-30 watts). Its tube has an outer diameter of 1.8 mm. This aspirator is designed to fragment and aspirate the cattle-liver. On observing the adjacent neural and vascular structures with the neuroendoscope, the massive hematoma within the ventricles is removed with the use of this aspirator. Subtotal removal (> 90% of hematoma volume) was achieved in all patients. All patients tolerated the procedure well. However, postoperative re-rupture occurred in two patients prior to aneurysm clipping following an immediate interval. Three patients with hypertension, two patients with head trauma, and one patient after aneurysm clipping were discharged home within one month after treatment. Preliminary experience with this aspirator has demonstrated its feasibility and safety. Clinical application of this technique is expected in other fields of neurosurgery.