Spinal lesions treated with Novalis shaped beam intensity-modulated radiosurgery and stereotactic radiotherapy

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 435-440 ◽  
Author(s):  
Antonio A. F. De Salles ◽  
Alessandra G. Pedroso ◽  
Paul Medin ◽  
Nzhde Agazaryan ◽  
Timothy Solberg ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Stereotactic Radiotherapy ◽  
Systemic Disease ◽  
Content Type ◽  
Shaped Beam ◽  
Intensity Modulated ◽  
Asymptomatic Patients ◽  
The Mean ◽  
Fine Print

Object. Spinal radiosurgery was implemented to improve quality of life (QOL) in patients with malignancies. It may also be applicable to the treatment of benign lesions. Methods. Between July 2002 and January 2004, 14 patients harboring 22 lesions were treated; 13 received single-dose stereotactic radiosurgery. Six were women. The mean age was 60.2 years (range 48–82 years). There were 11 metastases, two neurofibromas, and one meningioma. Six lesions were cervical, 10 thoracic, and six lumbar. Ten patients suffered pain, three paresthesias, two weakness, and three were asymptomatic. Seven patients underwent spinal surgery, with four receiving instrumentation. Twelve patients underwent conventional irradiation before stereotactic radiosurgery/stereotactic radiotherapy. A mean dose of 12 ± 2.7 Gy (range 8–21 Gy) was prescribed to the 91% isodose line (range 85–97%). The mean tumor volume was 25 ± 27.1 ml (range 0.75–91.8 ml). Treatment was planned using intensity-modulated radiosurgery (IMRS) fields in 15 cases, dynamic arcs in five, and conformal beams in two. The mean follow-up period was 6.1 ± 3.9 months (range 1–16 months). Three patients became pain free and four experienced considerable relief. Weakness improved in the two patients with this preoperative symptom and the asymptomatic patients remained so. Four lesions decreased in size, five remained stable, seven progressed, and six were not followed up (two patients died before follow up). Four patients in all died, three of systemic disease and one of thoracic lesion progression. No complications due to shaped beam and IMRS/intensity-modulated radiotherapy (IMRT) techniques were observed. Conclusions. Shaped beam and IMRS/IMRT involving the Novalis system may delay neurological deterioration, improving QOL. The lack of complication suggests that higher doses can be delivered to improve the control rate in patients with metastases.

Spinal lesions treated with Novalis shaped beam intensity-modulated radiosurgery and stereotactic radiotherapy

2004 ◽  
pp. 435-440 ◽  
Author(s):  
Antonio A. F. De Salles ◽  
Alessandra G. Pedroso ◽  
Paul Medin ◽  
Nzhde Agazaryan ◽  
Timothy Solberg ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Stereotactic Radiotherapy ◽  
Systemic Disease ◽  
Content Type ◽  
Shaped Beam ◽  
Intensity Modulated ◽  
Asymptomatic Patients ◽  
The Mean ◽  
Fine Print

Object. Spinal radiosurgery was implemented to improve quality of life (QOL) in patients with malignancies. It may also be applicable to the treatment of benign lesions. Methods. Between July 2002 and January 2004, 14 patients harboring 22 lesions were treated; 13 received single-dose stereotactic radiosurgery. Six were women. The mean age was 60.2 years (range 48–82 years). There were 11 metastases, two neurofibromas, and one meningioma. Six lesions were cervical, 10 thoracic, and six lumbar. Ten patients suffered pain, three paresthesias, two weakness, and three were asymptomatic. Seven patients underwent spinal surgery, with four receiving instrumentation. Twelve patients underwent conventional irradiation before stereotactic radiosurgery/stereotactic radiotherapy. A mean dose of 12 ± 2.7 Gy (range 8–21 Gy) was prescribed to the 91% isodose line (range 85–97%). The mean tumor volume was 25 ± 27.1 ml (range 0.75–91.8 ml). Treatment was planned using intensity-modulated radiosurgery (IMRS) fields in 15 cases, dynamic arcs in five, and conformal beams in two. The mean follow-up period was 6.1 ± 3.9 months (range 1–16 months). Three patients became pain free and four experienced considerable relief. Weakness improved in the two patients with this preoperative symptom and the asymptomatic patients remained so. Four lesions decreased in size, five remained stable, seven progressed, and six were not followed up (two patients died before follow up). Four patients in all died, three of systemic disease and one of thoracic lesion progression. No complications due to shaped beam and IMRS/intensity-modulated radiotherapy (IMRT) techniques were observed. Conclusions. Shaped beam and IMRS/IMRT involving the Novalis system may delay neurological deterioration, improving QOL. The lack of complication suggests that higher doses can be delivered to improve the control rate in patients with metastases.

Novalis Shaped Beam Radiosurgery of arteriovenous malformations

2004 ◽  
pp. 425-434
Author(s):  
Alessandra G. Pedroso ◽  
Antonio A. F. De Salles ◽  
Katayoun Tajik ◽  
Raymond Golish ◽  
Zachary Smith ◽  
...  
Keyword(s):  
Arteriovenous Malformations ◽  
Peripheral Dose ◽  
Content Type ◽  
Obliteration Rate ◽  
Shaped Beam ◽  
Martin Grade ◽  
The Mean ◽  
Per Se ◽  
Fine Print

Object. The authors studied outcomes and complications in patients who harbored arteriovenous malformations (AVMs) and underwent stereotactic radiosurgery involving the Novalis shaped beam unit. Methods. Between January 1998 and January 2002, 83 patients were treated with radiosurgery at University of California, Los Angeles. The mean patient age was 37.8 years. Forty-four patients completed follow up. There were 24 women. Sixteen patients underwent repeated radiosurgery. Embolization was performed in 13 patients and radiosurgery alone in 31. The mean follow-up period after embolization was 54.4 ± 21.9 months and 37.4 ± 14.6 months for radiosurgery alone. The mean peripheral dose was 15 Gy (range 12–18 Gy). The mean preradiosurgery lesion volume was 9.7 ± 11.9 ml for radiosurgery alone and 16.2 ± 11.3 ml for embolization. The AVMs in 13 patients (29.8%) were Spetzler—Martin Grade II, 12 (27.5%) were Grade III, eight (18.2%) Grade IV, and five (11.3%) were Grade V and VI each. Spetzler—Martin grade, volume, and peripheral dose were analyzed in consideration to outcome. A positive trend (p = 0.086) was observed between Spetzler—Martin grade and obliteration rate. Volume per se did not predict obliteration (p = 0.48). A peripheral dose of 18 Gy was shown to be the most important predictor for occlusion (p = 0.007). The overall obliteration rate was 52.5%. A transient complication was noticed in one case (2.3%) and but no permanent deficits due to radiosurgery have been detected so far. Three patients (6.8%) bled after radiosurgery. Conclusions. The range of the prescribed peripheral dose was narrow. An association between the mean peripheral dose of 15 Gy, high conformality, and homogeneous dose distribution permitted no permanent complications. Volume per se did not correlate with outcome. The next step will be to increase the peripheral dose shaping the beam and to achieve higher obliteration rates without increasing complications.

Novalis Shaped Beam Radiosurgery of arteriovenous malformations

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 425-434 ◽  
Author(s):  
Alessandra G. Pedroso ◽  
Antonio A. F. De Salles ◽  
Katayoun Tajik ◽  
Raymond Golish ◽  
Zachary Smith ◽  
...  
Keyword(s):  
Arteriovenous Malformations ◽  
Peripheral Dose ◽  
Content Type ◽  
Obliteration Rate ◽  
Shaped Beam ◽  
Martin Grade ◽  
The Mean ◽  
Per Se ◽  
Fine Print

Object. The authors studied outcomes and complications in patients who harbored arteriovenous malformations (AVMs) and underwent stereotactic radiosurgery involving the Novalis shaped beam unit. Methods. Between January 1998 and January 2002, 83 patients were treated with radiosurgery at University of California, Los Angeles. The mean patient age was 37.8 years. Forty-four patients completed follow up. There were 24 women. Sixteen patients underwent repeated radiosurgery. Embolization was performed in 13 patients and radiosurgery alone in 31. The mean follow-up period after embolization was 54.4 ± 21.9 months and 37.4 ± 14.6 months for radiosurgery alone. The mean peripheral dose was 15 Gy (range 12–18 Gy). The mean preradiosurgery lesion volume was 9.7 ± 11.9 ml for radiosurgery alone and 16.2 ± 11.3 ml for embolization. The AVMs in 13 patients (29.8%) were Spetzler—Martin Grade II, 12 (27.5%) were Grade III, eight (18.2%) Grade IV, and five (11.3%) were Grade V and VI each. Spetzler—Martin grade, volume, and peripheral dose were analyzed in consideration to outcome. A positive trend (p = 0.086) was observed between Spetzler—Martin grade and obliteration rate. Volume per se did not predict obliteration (p = 0.48). A peripheral dose of 18 Gy was shown to be the most important predictor for occlusion (p = 0.007). The overall obliteration rate was 52.5%. A transient complication was noticed in one case (2.3%) and but no permanent deficits due to radiosurgery have been detected so far. Three patients (6.8%) bled after radiosurgery. Conclusions. The range of the prescribed peripheral dose was narrow. An association between the mean peripheral dose of 15 Gy, high conformality, and homogeneous dose distribution permitted no permanent complications. Volume per se did not correlate with outcome. The next step will be to increase the peripheral dose shaping the beam and to achieve higher obliteration rates without increasing complications.

Stereotactic radiosurgery in the management of acoustic neuromas associated with neurofibromatosis Type 2

1999 ◽  
Vol 90 (5) ◽  
pp. 815-822 ◽  
Author(s):  
Brian R. Subach ◽  
Douglas Kondziolka ◽  
L. Dade Lunsford ◽  
David J. Bissonette ◽  
John C. Flickinger ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Neurofibromatosis Type ◽  
Tumor Control ◽  
Nerve Function ◽  
Content Type ◽  
Acoustic Neuromas ◽  
The Mean ◽  
Fine Print

Object. Stereotactically guided radiosurgery is one of the primary treatment modalities for patients with acoustic neuromas (vestibular schwannomas). The goal of radiosurgery is to arrest tumor growth while preserving neurological function. Patients with acoustic neuromas associated with neurofibromatosis Type 2 (NF2) represent a special challenge because of the risk of complete deafness. To define better the tumor control rate and long-term functional outcome, the authors reviewed their 10-year experience in treating these lesions.Methods. Forty patients underwent stereotactic radiosurgery at the University of Pittsburgh, 35 of them for solitary tumors. The other five underwent staged procedures for bilateral lesions (10 tumors, 45 total). Thirteen patients (with 29% of tumors) had undergone a median of two prior resections. The mean tumor volume at radiosurgery was 4.8 ml, and the mean tumor margin dose was 15 Gy (range 12–20 Gy).The overall tumor control rate was 98%. During the median follow-up period of 36 months, 16 tumors (36%) regressed, 28 (62%) remained unchanged, and one (2%) grew. In the 10 patients for whom more than 5 years of clinical and neuroimaging follow-up results were available (median 92 months), five tumors were smaller and five remained unchanged. Surgical resection was performed in three patients (7%) after radiosurgery; only one showed radiographic evidence of progression. Useful hearing (Gardner—Robertson Class I or II) was preserved in six (43%) of 14 patients, and this rate improved to 67% after modifications made in 1992. Normal facial nerve function (House—Brackmann Grade 1) was preserved in 25 (81%) of 31 patients. Normal trigeminal nerve function was preserved in 34 (94%) of 36 patients.Conclusions. Stereotactically guided radiosurgery is a safe and effective treatment for patients with acoustic tumors in the setting of NF2. The rate of hearing preservation may be better with radiosurgery than with other available techniques.

Stereotactic radiotherapy for the treatment of acoustic neuromas

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 362-372 ◽  
Author(s):  
Michael T. Selch ◽  
Alessandro Pedroso ◽  
Steve P. Lee ◽  
Timothy D. Solberg ◽  
Nzhde Agazaryan ◽  
...  
Keyword(s):  
Stereotactic Radiotherapy ◽  
Tumor Size ◽  
Cranial Nerve ◽  
Target Volume ◽  
Tumor Control ◽  
Content Type ◽  
Seventh Cranial Nerve ◽  
Acoustic Neuromas ◽  
Fine Print

Object. The authors sought to assess the safety and efficacy of stereotactic radiotherapy when using a linear accelerator equipped with a micromultileaf collimator for the treatment of patients with acoustic neuromas. Methods. Fifty patients harboring acoustic neuromas were treated with stereotactic radiotherapy between September 1997 and June 2003. Two patients were lost to follow-up review. Patient age ranged from 20 to 76 years (median 59 years), and none had neurofibromatosis. Forty-two patients had useful hearing prior to stereotactic radiotherapy. The fifth and seventh cranial nerve functions were normal in 44 and 46 patients, respectively. Tumor volume ranged from 0.3 to 19.25 ml (median 2.51 ml). The largest tumor dimension varied from 0.6 to 4 cm (median 2.2 cm). Treatment planning in all patients included computerized tomography and magnetic resonance image fusion and beam shaping by using a micromultileaf collimator. The planning target volume included the contrast-enhancing tumor mass and a margin of normal tissue varying from 1 to 3 mm (median 2 mm). All tumors were treated with 6-MV photons and received 54 Gy prescribed at the 90% isodose line encompassing the planning target volume. A sustained increase greater than 2 mm in any tumor dimension was defined as local relapse. The follow-up duration varied from 6 to 74 months (median 36 months). The local tumor control rate in the 48 patients available for follow up was 100%. Central tumor hypodensity occurred in 32 patients (67%) at a median of 6 months following stereotactic radiotherapy. In 12 patients (25%), tumor size increased 1 to 2 mm at a median of 6 months following stereotactic radiotherapy. Increased tumor size in six of these patients was transient. In 13 patients (27%), tumor size decreased 1 to 14 mm at a median of 6 months after treatment. Useful hearing was preserved in 39 patients (93%). New facial numbness occurred in one patient (2.2%) with normal fifth cranial nerve function prior to stereotactic radiotherapy. New facial palsy occurred in one patient (2.1%) with normal seventh cranial nerve function prior to treatment. No patient's pretreatment dysfunction of the fifth or seventh cranial nerve worsened after stereotactic radiotherapy. Tinnitus improved in six patients and worsened in two. Conclusions. Stereotactic radiotherapy using field shaping for the treatment of acoustic neuromas achieves high rates of tumor control and preservation of useful hearing. The technique produces low rates of damage to the fifth and seventh cranial nerves. Long-term follow-up studies are necessary to confirm these findings.

A fatal, chronically growing basilar artery: a new type of dissecting aneurysm

1996 ◽  
Vol 84 (6) ◽  
pp. 962-971 ◽  
Author(s):  
Tohru Mizutani
Keyword(s):  
Mr Imaging ◽  
Basilar Artery ◽  
Dissecting Aneurysm ◽  
Neurological Deficits ◽  
Vertebrobasilar Insufficiency ◽  
Content Type ◽  
Asymptomatic Patients ◽  
Basilar Arteries ◽  
Fine Print

✓ A long-term follow-up study (minimum duration 2 years) was made of 13 patients with tortuous dilated basilar arteries. Of these, five patients had symptoms related to the presence of such arteries. Symptoms present at a very early stage included vertebrobasilar insufficiency in two patients, brainstem infarction in two patients, and left hemifacial spasm in one patient. Initial magnetic resonance (MR) imaging in serial slices of basilar arteries obtained from the five symptomatic patients showed an intimal flap or a subadventitial hematoma, both of which are characteristic of a dissecting aneurysm. In contrast, the basilar arteries in the eight asymptomatic patients did not show particular findings and they remained clinically and radiologically silent during the follow-up period. All of the lesions in the five symptomatic patients gradually grew to fantastic sizes, with progressive deterioration of the related clinical symptoms. Dilation of the basilar artery was consistent with hemorrhage into the “pseudolumen” within the laminated thrombus, which was confirmed by MR imaging studies. Of the five symptomatic patients studied, two died of fatal subarachnoid hemorrhage (SAH) and two of brainstem compression; the fifth patient remains alive without neurological deficits. In the three patients who underwent autopsy, a definite macroscopic double lumen was observed in both the proximal and distal ends of the aneurysms within the layer of the thickening intima. Microscopically, multiple mural dissections, fragmentation of internal elastic lamina (IEL), and degeneration of media were diffusely observed in the remarkably extended wall of the aneurysms. The substantial mechanism of pathogenesis and enlargement in the symptomatic, highly tortuous dilated artery might initially be macroscopic dissection within a thickening intima and subsequent repetitive hemorrhaging within a laminated thrombus in the pseudolumen combined with microscopic multiple mural dissections on the basis of a weakened IEL. The authors note and caution that symptomatic, tortuous dilated basilar arteries cannot be overlooked because they include a group of malignant arteries that may grow rapidly, resulting in a fatal course.

Preliminary results of linear accelerator radiosurgery for acoustic schwannomas

1996 ◽  
Vol 85 (6) ◽  
pp. 1013-1019 ◽  
Author(s):  
William M. Mendenhall ◽  
William A. Friedman ◽  
John M. Buatti ◽  
Francis J. Bova
Keyword(s):  
Stereotactic Radiosurgery ◽  
Local Control ◽  
Linear Accelerator ◽  
Local Control Rate ◽  
Magnetic Resonance Images ◽  
High Rate ◽  
Content Type ◽  
Treatment Volume ◽  
Fine Print

✓ In this paper the authors evaluate the results of linear accelerator (LINAC)—based stereotactic radiosurgery for acoustic schwannomas. Fifty-six patients underwent LINAC-based stereotactic radiosurgery for acoustic schwannomas at the University of Florida between July 1988 and November 1994. Each patient was followed for a minimum of 1 year or until death; no patient was lost to follow up. One or more follow-up magnetic resonance images or computerized tomography scans were obtained in 52 of the 56 patients. Doses ranged between 10 and 22.5 Gy with 69.6% of patients receiving 12.5 to 15 Gy. Thirty-eight patients (68%) were treated with one isocenter and the dose was specified to the 80% isodose line in 71% of patients. Fifty-five patients (98%) achieved local control after treatment. The 5-year actuarial local control rate was 95%. At the time of analysis, 48 patients were alive and free of disease, seven had died of intercurrent disease, and one was alive with disease. Complications developed in 13 patients (23%). The likelihood of complications was related to the dose and treatment volume: 10 to 12.5 Gy to all volumes, three (13%) of 23 patients; 15 to 17.5 Gy to 5.5 cm3 or less, two (9%) of 23 patients; 15 to 17.5 Gy to more than 5.5 cm3, five (71%) of seven patients; and 20 to 22.5 Gy to all volumes, three (100%) of three patients. Linear accelerator—based stereotactic radiosurgery results in a high rate of local control at 5 years. The risk of complications is related to the dose and treatment volume.

Dynamic cranioplasty for brachycephaly in Apert syndrome: long-term follow-up study

2001 ◽  
Vol 94 (5) ◽  
pp. 757-764 ◽  
Author(s):  
José Guimarães-Ferreira ◽  
Fredrik Gewalli ◽  
Pelle Sahlin ◽  
Hans Friede ◽  
Py Owman-Moll ◽  
...  
Keyword(s):  
Cell Mass ◽  
Apert Syndrome ◽  
Long Term Results ◽  
Safe Procedure ◽  
Content Type ◽  
Skull Shape ◽  
The Mean ◽  
Fine Print

Object. Brachycephaly is a characteristic feature of Apert syndrome. Traditional techniques of cranioplasty often fail to produce an acceptable morphological outcome in patients with this condition. In 1996 a new surgical procedure called “dynamic cranioplasty for brachycephaly” (DCB) was reported. The purpose of the present study was to analyze perioperative data and morphological long-term results in patients with the cranial vault deformity of Apert syndrome who were treated with DCB. Methods. Twelve patients have undergone surgery performed using this technique since its introduction in 1991 (mean duration of follow-up review 60.2 months). Eleven patients had bicoronal synostosis and one had a combined bicoronal—bilambdoid synostosis. Perioperative data and long-term evolution of skull shape visualized on serial cephalometric radiographs were analyzed and compared with normative data. Changes in mean skull proportions were evaluated using a two-tailed paired-samples t-test, with differences being considered significant for probability values less than 0.01. The mean operative blood transfusion was 136% of estimated red cell mass (ERCM) and the mean postoperative transfusion was 48% of ERCM. The mean operative time was 218 minutes. The duration of stay in the intensive care unit averaged 1.7 days and the mean hospital stay was 11.8 days. There were no incidences of mortality and few complications. An improvement in skull shape was achieved in all cases, with a change in the mean cephalic index from a preoperative value of 90 to a postoperative value of 78 (p = 0.000254). Conclusions. Dynamic cranioplasty for brachycephaly is a safe procedure, yielding high-quality morphological results in the treatment of brachycephaly in patients with Apert syndrome.

Dose—response tolerance of the visual pathways and cranial nerves of the cavernous sinus to stereotactic radiosurgery

1998 ◽  
Vol 88 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Klaus A. Leber ◽  
Jutta Berglöff ◽  
Gerhard Pendl
Keyword(s):  
Stereotactic Radiosurgery ◽  
Cavernous Sinus ◽  
Dose Response ◽  
Cranial Nerves ◽  
Visual Pathways ◽  
Content Type ◽  
Number Of Patients ◽  
Response Tolerance ◽  
Fine Print

As the number of patients treated with stereotactic radiosurgery increases, it becomes particularly important to define with precision adverse effects on distinct structures of the nervous system. Object. This study was designed to assess the dose—response tolerance of the visual pathways and cranial nerves after exposure of the cavernous sinus to radiation. Methods. A total of 66 sites in the visual system and 210 cranial nerves of the middle cranial fossa were investigated in 50 patients who had undergone gamma knife treatment for benign skull base tumors. The mean follow-up period was 40 months (range 24–60 months). Follow-up examinations consisted of neurological, neuroradiological, and neuroophthalmological evaluations. The actuarial incidence of optic neuropathy was zero for patients who received a radiation dose of less than 10 Gy, 26.7% for patients receiving a dose in the range of 10 to less than 15 Gy, and 77.8% for those who received doses of 15 Gy or more (p < 0.0001). Previously impaired vision improved in 25.8% and was unchanged in 51.5% of patients. No sign of neuropathy was seen in patients whose cranial nerves of the cavernous sinus received radiation doses of between 5 and 30 Gy. Because tumor control appeared to have been achieved in 98% of the patients, the deterioration in visual function cannot be attributed to tumor progression. Conclusions. The structures of the visual pathways (the optic nerve, chiasm, and tract) exhibit a much higher sensitivity to single-fraction radiation than other cranial nerves, and their particular dose—response characteristics can be defined. In contrast, the oculomotor and trigeminal nerves have a much higher dose tolerance.

Preservation of olfaction in anterior craniofacial approaches

1993 ◽  
Vol 79 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Robert F. Spetzler ◽  
James M. Herman ◽  
Stephen Beals ◽  
Edward Joganic ◽  
John Milligan
Keyword(s):  
Cribriform Plate ◽  
Csf Leak ◽  
En Bloc ◽  
Reconstructive Procedures ◽  
Content Type ◽  
The Mean ◽  
Ethmoid Sinuses ◽  
Fine Print ◽  
Csf Leaks

✓ Through the combined efforts of neurosurgeons, head and neck surgeons, and craniofacial surgeons, the standard transbasal approach to the frontal fossa has been modified to include removal of the orbital roofs, nasion, and ethmoid sinuses. This approach has been combined further with facial disassembly procedures to provide extensive midline exposure to the midface and clival region. Extended frontal approaches, however, necessitate removal of the crista galli and sectioning of the olfactory rootlets with the associated risk of anosmia, cerebrospinal fluid (CSF) leak, and the need for complex reconstruction of the frontal floor. To avoid these problems, the authors have modified the technique of handling the cribriform plate to preserve the olfactory unit. Circumferential osteotomy cuts are made around the cribriform plate to allow an en bloc removal with its attachment to both the dura and underlying mucosa. Opening of the dura is avoided and the cribriform bone is used to reconstruct the floor. Four patients underwent this approach, for treatment of an angiofibroma in three and a fibrosarcoma in one. The mean follow-up period was 7 months. No patients developed a CSF leak, and within 8 weeks olfaction had returned in all patients. There was no other associated morbidity. These data suggest that this modification of the transbasilar approach can alleviate extensive reconstructive procedures and CSF leaks while preserving olfaction.

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