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  • Journal of Neurosurgery x
  • By Author: Kano, Hideyuki x
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Seyed H. Mousavi, Ajay Niranjan, Berkcan Akpinar, Marshall Huang, Hideyuki Kano, Daniel Tonetti, John C. Flickinger and L. Dade Lunsford

OBJECTIVE

In the era of MRI, vestibular schwannomas are often recognized when patients still have excellent hearing. Besides success in tumor control rate, hearing preservation is a main goal in any procedure for management of this population. The authors evaluated whether modified auditory subclassification prior to radiosurgery could predict long-term hearing outcome in this population.

METHODS

The authors reviewed a quality assessment registry that included the records of 1134 vestibular schwannoma patients who had undergone stereotactic radiosurgery during a 15-year period (1997–2011). The authors identified 166 patients who had Gardner-Robertson Class I hearing prior to stereotactic radiosurgery. Fifty-three patients were classified as having Class I-A (no subjective hearing loss) and 113 patients as Class I-B (subjective hearing loss). Class I-B patients were further stratified into Class I-B1 (pure tone average ≤ 10 dB in comparison with the contralateral ear; 56 patients), and I-B2 (> 10 dB compared with the normal ear; 57 patients). At a median follow-up of 65 months, the authors evaluated patients' hearing outcomes and tumor control.

RESULTS

The median pure tone average elevations after stereotactic radiosurgery were 5 dB, 13.5 dB, and 28 dB in Classes I-A, I-B1, and I-B2, respectively. The median declines in speech discrimination scores after stereotactic radiosurgery were 0% for Class I-A (p = 0.33), 8% for Class I-B1 (p < 0.0001), and 40% for Class I-B2 (p < 0.0001). Serviceable hearing preservation rates were 98%, 73%, and 33% for Classes I-A, I-B1, and I-B2, respectively. Gardner-Robertson Class I hearing was preserved in 87%, 43%, and 5% of patients in Classes I-A, I-B1, and I-B2, respectively.

CONCLUSIONS

Long-term hearing preservation was significantly better if radiosurgery was performed prior to subjective hearing loss. In patients with subjective hearing loss, the difference in pure tone average between the affected ear and the unaffected ear was an important factor in long-term hearing preservation.

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Greg Bowden, Hideyuki Kano, Ellen Caparosa, Daniel Tonetti, Ajay Niranjan, Edward A. Monaco III, John Flickinger, Yoshio Arai and L. Dade Lunsford

OBJECT

A visual field deficit resulting from the management of an arteriovenous malformation (AVM) significantly impacts a patient's quality of life. The present study was designed to investigate the clinical and radiological outcomes of stereotactic radiosurgery (SRS) performed for AVMs involving the postgeniculate visual pathway.

METHODS

In this retrospective single-institution analysis, the authors reviewed their experience with Gamma Knife surgery for postgeniculate visual pathway AVMs performed during the period between 1987 and 2009.

RESULTS

During the study interval, 171 patients underwent SRS for AVMs in this region. Forty-one patients (24%) had a visual deficit prior to SRS. The median target volume was 6.0 cm3 (range 0.4–22 cm3), and 19 Gy (range 14–25 Gy) was the median margin dose. Obliteration of the AVM was confirmed in 80 patients after a single SRS procedure at a median follow-up of 74 months (range 5–297 months). The actuarial rate of total obliteration was 67% at 4 years. Arteriovenous malformations with a volume < 5 cm3 had obliteration rates of 60% at 3 years and 79% at 4 years. The delivered margin dose proved significant given that 82% of patients receiving ≥ 22 Gy had complete obliteration. The AVM was completely obliterated in an additional 18 patients after they underwent repeat SRS. At a median of 25 months (range 11–107 months) after SRS, 9 patients developed new or worsened visual field deficits. One patient developed a complete homonymous hemianopia, and 8 patients developed quadrantanopias. The actuarial risk of sustaining a new visual deficit was 3% at 3 years, 5% at 5 years, and 8% at 10 years. Fifteen patients had hemorrhage during the latency period, resulting in death in 9 of the patients. The annual hemorrhage rate during the latency interval was 2%, and no hemorrhages occurred after confirmed obliteration.

CONCLUSIONS

Despite an overall treatment mortality of 5%, related to latency interval hemorrhage, SRS was associated with only a 5.6% risk of new visual deficit and a final obliteration rate close to 80% in patients with AVMs of the postgeniculate visual pathway.

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Daniel Tonetti, Hideyuki Kano, Gregory Bowden, John C. Flickinger and L. Dade Lunsford

Object

The presentation for patients with arteriovenous malformations (AVMs) is often intracranial hemorrhage; for women, this frequently occurs during the prime childbearing years. Although previous studies have addressed the risk for AVM hemorrhage during pregnancy, such studies have not assessed the risk for hemorrhage among women who become pregnant during the latency interval between stereotactic radiosurgery (SRS) and documented obliteration of the lesion. The authors sought to evaluate the risk for hemorrhage in patients who become pregnant during the latency interval after SRS.

Methods

This single-institution retrospective analysis reviewed the authors' experience with Gamma Knife SRS during 1987–2012. During this time, 253 women of childbearing age (median age 30 years, range 15–40 years) underwent SRS for intracranial AVM. The median target volume was 3.9 cm3 (range 0.1–27.1 cm3), and the median marginal dose was 20 Gy (range 14–38 Gy). For all patients, the date of AVM obliteration was recorded and the latency interval was calculated. Information about subsequent pregnancies and/or bleeding events during the latency interval was retrieved from the medical records and supplemented by telephone contact.

Results

AVM obliteration was confirmed by MRI or angiography at a median follow-up time of 39.3 months (range 10–174 months). There were 828.7 patient-years of follow-up within the latency interval between SRS and the date of confirmed AVM obliteration. Among nonpregnant women, 20 hemorrhages occurred before AVM obliteration, yielding an annual hemorrhage rate of 2.5% for nonpregnant women during the latency interval. Among women who became pregnant during the latency interval, 2 hemorrhages occurred over the course of 18 pregnancies, yielding an annual hemorrhage rate of 11.1% for women who become pregnant during the latency interval. For the 2 pregnant patients who experienced hemorrhage, the bleeding occurred during the first trimester of pregnancy.

Conclusions

The authors present the first series of data for women with intracranial AVMs who became pregnant during the latency interval after SRS. Hemorrhage during the latency interval occurred at an annual rate of 2.5% for nonpregnant women and 11.1% for pregnant women. The data suggest that pregnancy might be a risk factor for AVM hemorrhage during the interval between SRS and AVM obliteration. However, this suggestion is not statistically significant because only 18 patients in the study population became pregnant during the latency interval. To mitigate any increased risk for hemorrhage, patients should consider deferring pregnancy until treatment conclusion and AVM obliteration.

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Greg Bowden, Hideyuki Kano, Daniel Tonetti, Ajay Niranjan, John Flickinger, Yoshio Arai and L. Dade Lunsford

Object

Sylvian fissure arteriovenous malformations (AVMs) present substantial management challenges because of the critical adjacent blood vessels and functional brain. The authors investigated the outcomes, especially hemorrhage and seizure activity, after stereotactic radiosurgery (SRS) of AVMs within or adjacent to the sylvian fissure.

Methods

This retrospective single-institution analysis examined the authors' experiences with Gamma Knife surgery for AVMs of the sylvian fissure in cases treated from 1987 through 2009. During this time, 87 patients underwent SRS for AVMs in the region of the sylvian fissure. Before undergoing SRS, 40 (46%) of these patients had experienced hemorrhage and 36 (41%) had had seizures. The median target volume of the AVM was 3.85 cm3 (range 0.1–17.7 cm3), and the median marginal dose of radiation was 20 Gy (range 13–25 Gy).

Results

Over a median follow-up period of 64 months (range 3–275 months), AVM obliteration was confirmed by MRI or angiography for 43 patients. The actuarial rates of confirmation of total obliteration were 35% at 3 years, 60% at 4 and 5 years, and 76% at 10 years. Of the 36 patients who had experienced seizures before SRS, 19 (53%) achieved outcomes of Engel class I after treatment. The rate of seizure improvement was 29% at 3 years, 36% at 5 years, 50% at 10 years, and 60% at 15 years. No seizures developed after SRS in patients who had been seizure free before treatment. The actuarial rate of AVM hemorrhage after SRS was 5% at 1, 5, and 10 years. This rate equated to an annual hemorrhage rate during the latency interval of 1%; no hemorrhages occurred after confirmed obliteration. No permanent neurological deficits developed as an adverse effect of radiation; however, delayed cyst formation occurred in 3 patients.

Conclusions

Stereotactic radiosurgery was an effective treatment for AVMs within the region of the sylvian fissure, particularly for smaller-volume AVMs. After SRS, a low rate of hemorrhage and improved seizure control were also evident.

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Hideyuki Kano, John C. Flickinger, Huai-che Yang, Thomas J. Flannery, Daniel Tonetti, Ajay Niranjan and L. Dade Lunsford

Object

The purpose of this study was to define the outcomes and risks of stereotactic radiosurgery (SRS) for Spetzler-Martin (SM) Grade III arteriovenous malformations (AVMs).

Methods

Between 1987 and 2009, SRS was performed in 474 patients with SM Grade III AVMs. The AVMs were categorized by scoring the size (S), drainage (D), and location (L): IIIa was a small AVM (S1D1L1, N = 282); IIIb was a medium/deep AVM (S2D1L0, N = 44); and IIIc was a medium/eloquent AVM (S2D0L1, N = 148). The median target volume was 3.8 ml (range 0.1–26.3 ml) and the margin dose was 20 Gy (range 13–25 Gy). Eighty-one patients (17%) underwent prior embolization, and 58 (12%) underwent prior resection.

Results

At a mean follow-up of 89 months, the total obliteration rates documented by angiography or MRI for all SM Grade III AVMs increased from 48% at 3 years to 69% at 4 years, 72% at 5 years, and 77% at 10 years. The SM Grade IIIa AVMs were more likely to obliterate than other subgroups. The cumulative rate of hemorrhage was 2.3% at 1 year, 4.4% at 2 years, 5.5% at 3 years, 6.4% at 5 years, and 9% at 10 years. The SM Grade IIIb AVMs had a significantly higher cumulative rate of hemorrhage. Symptomatic adverse radiation effects were detected in 6%.

Conclusions

Treatment with SRS was an effective and relatively safe management option for SM Grade III AVMs. Although patients with residual AVMs remained at risk for hemorrhage during the latency interval, the cumulative 10-year 9% hemorrhage risk in this series may represent a significant reduction compared with the expected natural history.

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Greg Bowden, Hideyuki Kano, Daniel Tonetti, Ajay Niranjan, John Flickinger and L. Dade Lunsford

Object

Arteriovenous malformations (AVMs) of the posterior fossa have an aggressive natural history and propensity for hemorrhage. Although the cerebellum accounts for the majority of the posterior fossa volume, there is a paucity of stereotactic radiosurgery (SRS) outcome data for AVMs of this region. The authors sought to evaluate the long-term outcomes and risks of cerebellar AVM radiosurgery.

Methods

This single-institution retrospective analysis reviewed the authors' experience with Gamma Knife surgery during the period 1987–2007. During this time 64 patients (median age 47 years, range 8–75 years) underwent SRS for a cerebellar AVM. Forty-seven patients (73%) presented with an intracranial hemorrhage. The median target volume was 3.85 cm3 (range 0.2–12.5 cm3), and the median marginal dose was 21 Gy (range 15–25 Gy).

Results

Arteriovenous malformation obliteration was confirmed by MRI or angiography in 40 patients at a median follow-up of 73 months (range 4–255 months). The actuarial rates of total obliteration were 53% at 3 years, 69% at 4 years, and 76% at 5 and 10 years. Elevated obliteration rates were statistically higher in patients who underwent AVM SRS without prior embolization (p = 0.005). A smaller AVM volume was also associated with a higher rate of obliteration (p = 0.03). Four patients (6%) sustained a hemorrhage during the latency period and 3 died. The cumulative rates of AVM hemorrhage after SRS were 6% at 1, 5, and 10 years. This correlated with an overall annual hemorrhage rate of 2.0% during the latency interval. One patient experienced a hemorrhage 9 years after confirmed MRI and angiographic obliteration. A permanent neurological deficit due to adverse radiation effects developed in 1 patient (1.6%) and temporary complications were seen in 2 additional patients (3.1%).

Conclusions

Stereotactic radiosurgery proved to be most effective for patients with smaller and previously nonembolized cerebellar malformations. Hemorrhage during the latency period occurred at a rate of 2.0% per year until obliteration occurred.