Alberto Feletti and Pierluigi Longatti
Technical note and preliminary experience
Pierluigi Longatti, Luca Basaldella, Alberto Feletti, Alessandro Fiorindi and Domenico Billeci
Transaqueductal navigation of the fourth ventricle has long been considered dangerous and of no clinical relevance. After the refinement of the endoscopic technique and supported by the extensive experience gained at the authors' institution since 1994, endoscopic exploration of the fourth ventricle has been performed by the same surgeon in 54 patients. In all cases reviewed, endoscopic navigation of the fourth ventricle was successfully performed with no related neurological deficit. This preliminary experience shows the feasibility of transaqueductal navigation of the fourth ventricle, which is made possible by the use of small, flexible endoscopes in expert hands.
Pierluigi Longatti, Alessandro Fiorindi, Alberto Feletti and Vittorio Baratto
✓A membrane obstruction of the foramina of Magendie and Luschka is an uncommon origin of hydrocephalus characterized by unusual clinical symptoms of rhomboid fossa hypertension. Various surgical approaches have been proposed to alleviate this obstruction, including opening the obstructed foramen of Magendie using suboccipital craniectomy, shunting procedures, and more recently, endoscopic third ventriculostomy (ETV). In some cases, however, reshaping of the posterior fossa due to the collapse of the prepontine cistern could make ETV difficult for the surgeon and dangerous to the patient. In these cases, endoscopic opening of the foramen of Magendie by transaqueductal navigation of the fourth ventricle is a suitable and feasible therapeutic option.
Case report and review of the literature
Elisabetta Marton, Alberto Feletti, Enrico Orvieto and Pierluigi Longatti
✓The authors present the case of a dumbbell-shaped malignant psammomatous melanotic schwannoma of the upper cervical spine involving the C-2 sensory root. The family of the patient had a history of other malignant stromal tumors, without the Carney complex genetic pattern. The 30-year-old female patient complained of experiencing cervical pain and cervical muscle contractions for 6 months, and was admitted to the hospital. The cervical T1-weighted magnetic resonance (MR) images revealed the presence of a slightly hyperintense C2–3 intra–extradural lesion, moderately enhancing, which had eroded and enlarged the intervertebral foramen. The patient workup also included computed tomography scans and angiography. A posterior approach was used to perform a C2–3 hemilaminectomy, including opening of the dura mater and gross-total removal of the lesion. Histopathological examination of the lesion revealed it to be a malignant psammomatous melanotic schwannoma. The cerebrospinal MR image of the patient obtained at the 12-month follow-up examination demonstrated the presence of tumor progression into the subarachnoid space at the C-3 level. The strong malignancy potential of the lesion must be considered in the future management of the patient, especially due to the presence in the family of other stromal tumors such as gastrointestinalstromal tumors and malignant melanomas. The authors review all the literature concerning melanotic schwannomas and report 105 cases of melanotic schwannoma that were not related to the Carney complex. The particular focus of their review is on the characteristics of the malignant progression of melanotic schwannoma, such as local recurrences, metastasis, and survival rate.
Report of 6 cases
Alberto Feletti, Giannantonio Zanata Santi, Francesco Sammartino, Marzio Bevilacqua, Piero Cisotto and Pierluigi Longatti
Peripheral nerve field stimulation has been successfully used for many neuropathic syndromes. However, it has been reported as a treatment for trigeminal neuropathic pain or persistent idiopathic facial pain only in the recent years.
The authors present a review of the literature and their own series of 6 patients who were treated with peripheral nerve stimulation for facial neuropathic pain, reporting excellent pain relief and subsequent better social relations and quality of life.
On average, pain scores in these patients decreased from 10 to 2.7 on the visual analog scale during a 17-month follow-up (range 0–32 months). The authors also observed the ability to decrease trigeminal pain with occipital nerve stimulation, clinically confirming the previously reported existence of a close anatomical connection between the trigeminal and occipital nerves (trigeminocervical nucleus).
Peripheral nerve field stimulation of the trigeminal and occipital nerves is a safe and effective treatment for trigeminal neuropathic pain and persistent idiopathic facial pain, when patients are strictly selected and electrodes are correctly placed under the hyperalgesia strip at the periphery of the allodynia region.
Pierluigi Longatti, Andrea Porzionato, Luca Basaldella, Alessandro Fiorindi, Pietro De Caro and Alberto Feletti
The human area postrema (AP) is a circumventricular organ that has only been described in cadaveric specimens and animals. Because of its position in the calamus scriptorius and the absence of surface markers on the floor of the fourth ventricle, the AP cannot be clearly localized during surgical procedures.
The authors intravenously administered 500 mg fluorescein sodium to 25 patients during neuroendoscopic procedures; in 12 of these patients they explored the fourth ventricle. A flexible endoscope equipped with dual observation modes for both white light and fluorescence was used. The intraoperative fluorescent images were reviewed and compared with anatomical specimens and 3D reconstructions.
Because the blood-brain barrier does not cover the AP, it was visualized in all cases after fluorescein sodium injection. The AP is seen as 2 coupled leaves on the floor of the fourth ventricle, diverging from the canalis centralis medullaris upward. Although the leaves normally appear short and thick, there can be different morphological patterns. Exploration using the endoscope's fluorescent mode allowed precise localization of the AP in all cases.
Fluorescence-enhanced inspection of the fourth ventricle accurately identifies the position of the AP, which is an important landmark during surgical procedures on the brainstem. A better understanding of the AP can also be valuable for neurologists, considering its functional role in the regulation of homeostasis, emesis, and cardiovascular and electrolyte balance. Despite the limited number of cases in this report, evidence indicates that the normal anatomical appearance of the AP is that of 2 short and thick leaves that are joined at the midline. However, there can be great variability in terms of the structure's shape and size.
Alberto Feletti, Elisabetta Marton, Grazia Marina Mazzucco, Shanna Fang and Pierluigi Longatti
Since children may not be able to complain of progressive reduction in optic acuity, visual assessment in infancy may present practical difficulties. The authors report a case of craniopharyngioma, which led a young child to early blindness before the correct diagnosis could be made. Similar to other reported cases, the authors found that surgery did not substantially modify the preoperative visual deficit. They conclude that minimal improvement in visual acuity can be expected despite successful microsurgical removal of the tumor.
Pierluigi Longatti, Alessandro Fiorindi, Alberto Feletti, Domenico D'Avella and Andrea Martinuzzi
Microsurgical anatomy of the fourth ventricle has been comprehensively addressed by masterly reports providing classic descriptions of this complex region. Neuroendoscopy could offer a new, somewhat different perspective of the “inside” view of the fourth ventricle. The purpose of this study was to examine from the anatomical point of view the access to the fourth ventricle achieved by the endoscopic transaqueductal approach, to enumerate and describe the anatomically identifiable landmarks, and to compare them with those described during microsurgery.
The video recordings of 52 of 75 endoscopic explorations of the fourth ventricle performed at the authors' institution for different pathological conditions were reviewed and evaluated to identify and describe every anatomical landmark. According to the microsurgical anatomy, at least 23 superficial structures are clearly identifiable in the fourth ventricle, and they represent the comparative basis of parallel endoscopic anatomy of the structures found during the fourth ventricle navigation.
The following anatomical structures were identified in all cases: median sulcus, superior and inferior vela medullare, choroid plexus, inferior fovea, hypoglossal and vagal triangles, area postrema, obex, canalis medullaris, lateral recess, and the foramina of Luschka and Magendie. The median eminence, facial colliculus, striae medullaris, auditory tubercle, and inferior fovea were seen in the majority of cases. The locus caevruleus could never be seen.
On the whole, 20 anatomical structures could consistently be identified by exploring the fourth ventricle with a fiberscope. Neuroendoscopy offers a quite different outlook on the anatomy of the fourth ventricle, and compared with the microsurgical descriptions it seems to provide a superior and detailed visualization, particularly of the structures located in the inferior triangle.
Alberto Feletti, Luca Denaro, Roberto Faggin, Pietro Ciccarino, Marta Rossetto and Domenico d'Avella
Alberto Feletti, Alessandro Fiorindi, Vincenzo Lavecchia, Rafael Boscolo-Berto, Elisabetta Marton, Veronica Macchi, Raffaele De Caro, Pierluigi Longatti, Andrea Porzionato and Giacomo Pavesi
Despite the technological advancements of neurosurgery, the posterior part of the third ventricle has always been the “dark side” of the ventricle. However, flexible endoscopy offers the opportunity for a direct, in vivo inspection and detailed description of the posterior third ventricle in physiological and pathological conditions. The purposes of this study were to describe the posterior wall of the third ventricle, detailing its normal anatomy and surgical landmarks, and to assess the effect of chronic hydrocephalus on the anatomy of this hidden region.
The authors reviewed the video recordings of 59 in vivo endoscopic explorations of the posterior third ventricle to describe every identifiable anatomical landmark. Patients were divided into 2 groups based on the absence or presence of a chronic dilation of the third ventricle. The first group provided the basis for the description of normal anatomy.
The following anatomical structures were identified in all cases: adytum of the cerebral aqueduct, posterior commissure, pineal recess, habenular commissure, and suprapineal recess. Comparing the 2 groups of patients, the authors were able to detect significant variations in the shape of the adytum of the cerebral aqueduct and in the thickness of the habenular and posterior commissures. Exploration with sodium fluorescein excluded the presence of any fluorescent area in the posterior third ventricle, other than the subependymal vascular network.
The use of a flexible scope allows the complete inspection of the posterior third ventricle. The anatomical variations caused by chronic hydrocephalus might be clinically relevant, in light of the commissure functions.