Biomedical subjects

Harry R van Loveren

Publications and source records attributed to Harry R van Loveren.

11 recordsLinked to original sources

PubMed2006

The subtemporal interdural approach to dumbbell-shaped trigeminal schwannomas: cadaveric prosection.

OBJECTIVE: Successful resection of dumbbell-shaped trigeminal schwannomas via a subtemporal interdural approach requires an understanding of both the anatomy related to the bone dissection of the petrous apex (Kawase's triangle or quadrilateral) and meningeal anatomy. We studied the meningeal anatomy related to this approach and describe the dural incisions and stepwise mobilization. METHODS: Meningeal anatomy around Meckel's cave and porus trigeminus was examined during the subtemporal interdural anterior transpetrosal approach in both sides of 15 cadaveric heads. Histological study of the Meckel's cave region was performed in two cadaveric heads. RESULTS: The Gasserian ganglion and trigeminal roots have two layers of dura propria on their dorsolateral surface: an inner layer from the posterior fossa dura propria that constitutes the dorsolateral wall of Meckel's cave and an outer layer from the dura propria of the middle fossa. The cleavage plane between these two layers continues distally as the cleavage plane between the epineural sheaths of the trigeminal divisions and the dura propria of the middle fossa. This cleavage plane serves as the anatomic landmark for the interdural exposure of the contents of Meckel's cave. The superior petrosal sinus is sectioned at the medial aspect of Kawase's triangle and reflected along with the porus trigeminus roof. CONCLUSION: Understanding the critical meningeal architecture in and around Meckel's cave allows experienced cranial neurosurgeons to develop a subtemporal interdural approach to dumbbell-shaped trigeminal schwannomas that effectively converts a multiple-compartment tumor into a single-compartment tumor. Dural incisions and stepwise mobilization complements our previous description of the bony dissection for this approach.

Cadaver↗

PubMed2005

Transcranial surgery for pituitary adenomas.

Although the transsphenoidal approach is the preferred approach to the vast majority of pituitary tumors with or without suprasellar extension, the transcranial approach remains a vital part of the neurosurgical armamentarium for 1 to 4% of these tumors. The transcranial approach is effective when resection becomes necessary for a portion of a pituitary macroadenoma that is judged to be inaccessible from the transsphenoidal route because of isolation by a narrow waist at the diaphragma sellae, containment within the cavernous sinus lateral to the carotid artery, projection anteriorly onto the planum sphenoidale, or projection laterally into the middle fossa. The application of a transcranial approach in these circumstances may still be mitigated by response to prolactin inhibition of prolactinomas, the frequent lack of necessity to remove asymptomatic nonsecretory adenomas from the cavernous sinus, and the lack of evidence that sustained chemical cures can be reliably achieved by removal of secretory adenomas (adrenocorticotropic hormone, growth hormone) from the cavernous sinus. Cranial base surgical techniques have refined the surgical approach to pituitary adenomas but have had less effect on actual surgical indications than anticipated. Because application of the transcranial approach to pituitary adenomas is and should be rare in clinical practice, it is useful to standardize the technique to a default mode with which the surgical team is most experienced and, therefore, most comfortable. Our default mode for transcranial pituitary surgery is the frontotemporal-orbitozygomatic approach.

Adenoma↗

PubMed2005

Microvascular retractor: a new concept of retracting and repositioning cerebral blood vessels.

OBJECTIVE: In this technical note, we report our results with a newly designed retractor blade that can be directly applied for the retraction and repositioning of cerebral blood vessels and delicate neural structures. METHODS: This new malleable retractor with a semicircular tip was designed to fit in the flexible arms of a self-retaining retractor system. After prototype evaluation and optimization in laboratory studies, we used the new retractor in 15 patients during surgical procedures that included retraction of the internal carotid artery during aneurysm clipping, expansion of the surgical window, and transposition of cranial nerves. RESULTS: No intraoperative injuries occurred to neurovascular structures. The retractor blade remained stable on pulsating vessels during the procedure and largely preserved the vessel diameter. CONCLUSION: The new retractor incorporates the existing advantages offered by flexible self-retaining retractor blades with those features that adapt to blood vessel retraction. Rather than concentrating force at one point as typical retractors do, the semicircular tip distributes the retraction force over multiple points along its circumference.

Aneurysm↗

PubMed2004

The carotid-oculomotor window in exposure of upper basilar artery aneurysms: a cadaveric morphometric study.

OBJECTIVE: The carotid-oculomotor window remains the traditional deep window in the exposure of aneurysms of the upper basilar artery. Although several techniques have been described to expand this window, few morphometric studies document either the degree of its expansion or its contribution to the exposure of the basilar artery. We review the microsurgical anatomy of the carotid-oculomotor window, describe expansion techniques, and analyze morphometrically the contribution of each step (i.e., extradural anterior clinoidectomy, mobilization of the internal carotid artery [ICA], and posterior clinoidectomy) to the expansion of the window and/or exposure of the artery. METHODS: Ten formalin-fixed, alcohol-preserved, cadaver heads injected with pigmented silicone were prepared for bilateral dissection. The vertebrobasilar system was injected with pigmented silicone mixed with barium (1:1), rendering it radiopaque. After completing a frontotemporal-orbitozygomatic craniotomy, we performed dissection in two stages: Stage I consisted of a conventional transsylvian exposure of the upper basilar artery through the carotid-oculomotor window; and Stage II added anterior clinoidectomy, ICA mobilization, and posterior clinoidectomy. A clip was applied to the lowest accessible point of the basilar trunk at each stage. Measurements obtained during each stage included: 1). the transverse carotid-oculomotor distance, that is, anteriorly between the oculomotor foramen and ICA, and posteriorly between the oculomotor nerve and ICA; and 2). the exposed length of the basilar artery, as seen under the microscope and on angiograms. RESULTS: Measurements were obtained before and after the addition of anterior clinoidectomy, mobilization of the ICA, and posterior clinoidectomy. Increases in expansion of the window and exposure of the upper basilar artery were documented as percentages of the control values. The anterior carotid-oculomotor distance averaged 7.1 mm (range, 5-10 mm) and 10.1 mm (range, 7-15 mm) before and after the additional surgical steps to expand the window, respectively. The posterior carotid-oculomotor distance averaged 12.7 mm (range, 9-18 mm) and 16.1 mm (range, 11-22 mm) before and after the additional surgical steps to expand the window, respectively. The exposed length of the basilar artery from the bifurcation to the clip was 4.2 mm (range, 1-13 mm) before expansion and 7 mm (range, 3-15 mm) after expansion. CONCLUSION: Anterior clinoidectomy and ICA mobilization increased the carotid-oculomotor space 44% anteriorly and 28% posteriorly. Posterior clinoidectomy increased the exposed length of the basilar artery by 69%. Superficial wide field exposure, expansion of the carotid-oculomotor window, and increased exposure of the upper basilar artery facilitate both visualization of the aneurysm for clip application and the use of proximal vascular control as an adjunct to basilar aneurysm surgery.

Basilar Artery↗

PubMed2004

Large sphenoid wing meningiomas involving the cavernous sinus: conservative surgical strategies for better functional outcomes.

OBJECTIVE: The ability to resect meningiomas that involve the medial and anterior compartments of the cavernous sinus has been refuted. In this retrospective study, we determined the efficacy of total resection of meningiomas that invade the cavernous sinus but are restricted to the lateral compartment. METHODS: We reviewed the charts of 38 consecutive patients with sphenocavernous, clinoidocavernous, and sphenoclinoidocavernous meningiomas who underwent surgical treatment. We assessed early and late cranial nerve morbidity, extent of resection, and long-term outcome (mean, 96 mo). RESULTS: In all patients, tumors exceeded 3 cm diameter. In 22 of 24 patients, total microscopic excision was achieved in tumors that involved only the lateral compartment of the cavernous sinus and touched or partially encased the cavernous internal carotid artery (i.e., modified Hirsch Grades 0 and 1, respectively). In 2 of 24 patients, remaining tumor infiltrated the superior orbital fissure. All 14 patients who had tumors that encased (with or without narrowing) the cavernous segment of the internal carotid artery (Hirsch Grades 2-4) underwent incomplete resection. Among 38 patients, mortality was 0%, late cranial nerve deficits remained in 6 (16%), and late Karnofsky Performance Scale scores exceeded 90 in 34 patients (90%). Four patients (10.5%) developed a recurrence or regrowth. Of 20 patients who were treated with either linear accelerator-based stereotactic radiosurgery or fractionated conformal radiotherapy, 11 had residual tumor and a moderate to high proliferative index, 4 had atypical tumors and 1 had angioblastic meningioma after total excision, 2 had regrowth, and 2 had recurrent tumors. In 18 (90%) of the 20 patients who underwent radiation, tumor size was reduced or controlled. CONCLUSION: On the basis of this study and a review of the literature, we demonstrate that sphenocavernous, clinoidocavernous, and sphenoclinoidocavernous meningiomas of Hirsch Grades 0 and 1 can be excised from the lateral compartment of the cavernous sinus without postoperative mortality and with acceptable rates of morbidity. Residual tumor in the medial compartment (Hirsch Grades 2-4) may be treated with some form of radiation therapy or observation.

Adult↗

PubMed2003

The One-Piece Orbitopterional Approach.

The orbitopterional approach is an anterior skull base extension of the pterional approach that provides greater exposure to the anterior cranial fossa, supra- and parasellar regions, and anterior communicating artery complex. We describe the surgical technique in a stepwise manner to create a one-piece orbitopterional craniotomy flap; keyholes for the bone cuts are the MacCarty burr-hole and the anterolateral portion of the inferior orbital fissure. This one-piece technique is less complicated than the two-piece orbitopterional craniotomy and eliminates the need for complex reconstruction of cosmetically important areas (i.e., the orbit and forehead).

Journal Article↗

PubMed2003

Subtonsillar approach to the foramen of Luschka: an anatomic and clinical study.

OBJECTIVE: Conventional approaches to tumors of the foramen of Luschka are limited because the foramen is viewed from either the fourth ventricle laterally (transvermian approach) or the cerebellopontine angle medially (suboccipital approach). The definitive approach is subtonsillar, because the foramen of Luschka is actually the end of the natural cleavage plane between the cerebellar tonsil and the medulla. We describe the microsurgical anatomic features of the foramen of Luschka region and the operative technique for the subtonsillar approach to this region. METHODS: In the anatomic study, five formalin-fixed, silicone-injected, cadaveric heads were used. In the clinical study, the records for five patients treated via the subtonsillar approach were examined; several illustrative cases are presented. RESULTS: The foramen of Luschka is formed by the tela choroidea and the rhomboid lip and exists at the lateral end of the cerebellomedullary fissure, which is a natural cleavage plane between the cerebellar tonsil and the medulla. The subtonsillar approach is performed via a suboccipital craniotomy; the patient is positioned in the lateral decubitus position, with the tumor side down. After the cerebellar tonsil is freed from arachnoid adhesions, it can be retracted rostrodorsally from the medulla, to expose the cerebellomedullary fissure. Clinically, the tela choroidea and rhomboid lip are significantly attenuated by tumor expansion. Therefore, by dissecting in a subtonsillar manner around the tumor, one can reach the foramen of Luschka without traversing any neural tissue. CONCLUSION: The subtonsillar approach yields a panoramic view to the foramen of Luschka laterally and up to the middle cerebellar peduncle superiorly. This approach minimizes the distance between the tumor and the surgeon, while maximizing neural preservation. We think this is the definitive approach to this difficult region of the posterior fossa.

Adult↗

PubMed2002

Indications for endovascular therapy for refractory vasospasm after aneurysmal subarachnoid hemorrhage: experience at the University of Cincinnati.

BACKGROUND: Transluminal balloon angioplasty (TBA) and intra-arterial papaverine (IAP) appear to be valuable alternatives for the treatment of aneurysmal subarachnoid hemorrhage (SAH)-induced vasospasm refractory to maximal medical therapy. Although widely used, guiding principles for the implementation of TBA and IAP are not yet established. Based on our retrospective analysis, we define guidelines for endovascular therapy for refractory vasospasm based on our clinical results, adverse effects, and pattern of vasospasm. METHODS: Medical records of 62 patients who experienced aneurysmal SAH-induced vasospasm refractory to hypervolemic, hypertensive, hyperdynamic therapy, and who were treated with IAP or TBA were reviewed. Fifty patients met the inclusion criteria for analysis. After careful scrutiny, two types of responses to endovascular treatment were identified. On the basis of that grouping, patients were divided into two groups according to the number of arterial segments involved, that is, monoterritorial and multiterritorial vasospasm. Multiple variables were analyzed. RESULTS: Patients undergoing multiple endovascular procedures exhibited the worst outcomes. Patients in the monoterritorial group experienced a higher incidence of clinical improvement and better outcomes after endovascular treatment. Elevated intracranial pressure (ICP) and ICP-related deaths were more prominent in the multiterritorial group of patients. Sustained ICP elevation after administration of IAP was strongly associated with poor outcome in the multiterritorial group. CONCLUSIONS: IAP is indicated as an early potential single-dose infusion in distal monoterritorial vasospasm, if angioplasty is impossible or unsafe. The use of IAP in bilateral diffuse vasospasm is discouraged because of the high susceptibility of these patients to develop elevated ICP. Multiple IAP infusions seem to have no significant impact on patient outcome. Balloon angioplasty seems to be indicated at an early juncture in patients with multiterritorial proximal vasospasm.

Adult↗

PubMed2002

Facial nerve neuromas: report of 10 cases and review of the literature.

OBJECTIVE: This study reviewed the management and outcomes of facial neuromas during the past decade at our institution. The goal was to analyze differences in presentation on the basis of location of the facial neuroma, review facial nerve function and hearing preservation postoperatively, and understand the characteristics of patients with tumors limited to the cerebellopontine angle or internal auditory canal. We also report an unusual case of a facial neuroma limited to the nervus intermedius. METHODS: Nine patients with facial neuromas and one with Jacobson's nerve neuroma underwent surgery, and total resection was accomplished in nine patients. A chart review for pre- and postoperative data was performed, after which all patients were evaluated on an outpatient basis. RESULTS: The mean age of the patients was 47 years; mean follow-up time was 33.1 months. The most common presenting symptoms were hearing loss (six patients) and facial paresis (five patients). A total of five patients had progressive (four patients) or recurrent (one patient) facial paresis. No patient experienced worsened hearing as a result of surgery, and one experienced improvement in a conductive hearing deficit. Five patients required cable graft repair of the facial nerve; four improved to House-Brackmann Grade 3 facial paresis. Four of five patients with preserved anatomic continuity of the facial nerve regained normal facial function. There were no surgical complications. No tumors have recurred during follow-up. We report the second nerve sheath tumor limited to the nervus intermedius. CONCLUSION: This series documents that facial neuromas can be resected safely with preservation of facial nerve and hearing function. Preservation of anatomic continuity of the facial nerve should be attempted, and it does not seem to lead to frequent recurrence. Tumors limited to the cerebellopontine angle/internal auditory canal are a unique subset of facial neuromas with characteristics that vary greatly from facial neuromas in other locations, and they are indistinguishable clinically from acoustic neuromas.

Adult↗

PubMed2002

Acute foramen magnum syndrome caused by an acquired Chiari malformation after lumbar drainage of cerebrospinal fluid: report of three cases.

OBJECTIVE AND IMPORTANCE: The perioperative use of lumbar drainage of cerebrospinal fluid (CSF) is relatively common in neurosurgery, and the development of "acquired" Chiari malformations (tonsillar herniation) with lumbar CSF diversion procedures has been reported. CLINICAL PRESENTATION: We describe the history of three patients who developed a foramen magnum syndrome, attributable to acquired Chiari I malformations, after perioperative lumbar drainage of CSF. CONCLUSION: We propose that the mechanism responsible for Chiari I malformations involves a negative pressure gradient between the cranial and spinal regions, created by CSF drainage. Theories regarding the formation of acquired Chiari I malformations, the possible synergistic roles of intracranial pathological conditions and CSF drainage in the development of this entity, and the implications for the use of perioperative lumbar drainage are discussed.

Acute Disease↗

PubMed2002

Commentary.

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Journal Article↗