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2. Brooks DJ: Positron emission tomographic studies of subcortical degenera- innovative keyhole approach to arachnoid fenestration as tions and . Semin Neurol 9:351–359, 1989. a safe effective method for treating middle fossa , we had 3. Brooks DJ, Ibanez V, Swale G, Quinn N, Lee AJ, Mathias CJ, Bannister R, Marsden CD, Frackowiak RS: Differing patterns of striatal 18F-dopa uptake in the impression that during the decision-making process, the Parkinson’s disease, , and progressive supranuclear authors focused their attention on the arachnoid cysts, placing palsy. Ann Neurol 28:547–555, 1990. important associated pathological findings in second place, 4. Farde L, Eriksson L, Blomquist G, Halldin C: Kinetic analysis of central specifically in the case of children with . [11C]raclopride binding to D2-dopamine receptors studied by PET: A comparison to the equilibrium analysis. J Cereb Blood Flow Metab 9:696–708, 1989. Arachnoid cysts presumably result from an aberration in 5. Swale GV, Wroe SJ, Lees AL, Brooks DJ, Frackowiak RS: The identification of the embryological development of the subarachnoid space (4). presymptomatic : Clinical and [18F]dopa positron emission to- This hypothesis seems to be the reason for the actual disorder mography studies in an Irish kindred. Ann Neurol 32:609–617, 1992.

in the circulation and why subarachnoid Downloaded from https://academic.oup.com/neurosurgery/article/56/3/E629/2740249 by guest on 28 September 2021 In Reply: cysts are frequently associated with hydrocephalus. Whether We thank Dr. Sakellaridis for his comments on our article the cyst is the cause of the ventriculomegalia is a clinical and (1). In response, we offer the following points. therapeutic dilemma. In some patients, the location of the cyst The administration of l-dopa results in the amelioration of interferes with the normal cerebrospinal fluid circulation (i.e., the motor symptoms of PD. Studies have demonstrated that those compressing the sylvian aqueduct or those obstructing this improvement in motor symptoms is associated with bind- the outlet foramina in the fourth ventricle); however, in some ing of DA to DA receptors as visualized by the competitive cases, there is no evident relationship between the cysts and displacement of previously administered labeled [11C]raclo- the ventricular enlargement. In those situations, some authors pride (2) in the form of occupied striatal receptors. support the idea that the hydrocephalus is communicating Stimulation of the subthalamic nucleus (STN) similarly re- and the actual problem is in the subarachnoid space, similar to sults in amelioration of the motor symptoms of PD. Given the their subarachnoid cyst counterparts (5). This could be the similarities in clinical effect between l-dopa administration reason for the low incidence of hydrocephalus (15–18%) in and STN stimulation, we tested the hypothesis that effective children with middle fossa arachnoid cysts (1, 3). STN stimulation would also result in the displacement of In this article, Levy et al. (2) use the microsurgical keyhole 11 striatal [ C]raclopride. We found, however, that there was no approach as the initial procedure for treatment of middle fossa 11 significant displacement of striatal [ C]raclopride in response arachnoid cysts, including those in three moderately hydro- to STN stimulation, and therefore concluded—given the lim- cephalic patients. It is about those patients that we have some itations outlined in our Discussion—that this is not the pri- concerns. Were their complaints secondary to hydrocephalus mary mechanism of action of STN stimulation. or to the cysts? Why does the ventricular size remain stable Aviva Abosch after the surgical procedure? In this situation, it is advisable to Shitij Kapur determine whether these stable patients were functioning at Anthony E. Lang their full potential or whether their neurological function Doug Hussey could be improved after surgical diversion. In these patients, Elspeth Sime it is also necessary to define whether they had arrested or Janis Miyasaki compensated hydrocephalus. Sylvain Houle Because this procedure provides communication between the Andres M. Lozano cyst and the basal cisterns, we agree with the authors that the Toronto, Ontario, Canada proposed technique is useful for arachnoid cysts without hydro- cephalus. In patients harboring middle fossa arachnoid cysts and hydrocephalus, the diversion of the cyst could not be effective; 1. Abosch A, Kapur S, Lang AE, Hussey D, Sime E, Miyasaki J, Houle S, Lozano thus, the ventricular enlargement should be approached inde- AM: Stimulation of the subthalamic nucleus in Parkinson’s disease does not pendently, as suggested by Raffel and McComb (3). produce striatal dopamine release. 53:1095–1105, 2003 2. Tedroff J, Pederson M, Aquilonius SM, Hartvig P, Jacobsson G, Langstrom B: Odalys Hernàndez Leòn Levodopa-induced changes in synaptic dopamine in patients with Raúl Andrés Pérez Falero Parkinson’s disease as measured by [11C]-raclopride displacement and PET. Neurology 46:1430–1436, 1996. Ivàn F. Arenas Rodrìguez Carlos Lozano Crespo Palacio Pinar del Rio, Cuba DOI: 10.1227/01.NEU.0000155087.93120.06

Microsurgical Keyhole Approach for Middle Fossa 1. Ciricillo SF, Cogen PH, Harsh GR, Edwards MS: Intracranial arachnoid cysts Arachnoid Cyst Fenestration in children: A comparison of the effects of fenestration and shunting. J Neurosurg 74:230–235, 1991. To the Editor: 2. Levy ML, Wang M, Aryan HE, Yoo K, Meltzer H: Microsurgical keyhole We read with great interest the recently published article by approach for middle fossa arachnoid cyst fenestration. Neurosurgery 53: Levy et al. (2). Regardless of the original description of this 1138–1145, 2003.

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3. Raffel C, McComb JG: To shunt or to fenestrate: Which is the best surgical not be picked up as well as on standard DSA and the images treatment for arachnoid cysts in pediatric patients? Neurosurgery 23:338–342, certainly are not comparable to those on three-dimensional DSA. 1988. 4. Rengachary SS, Watanabe I: Ultrastructure and pathogenesis of intracranial Learning from our mistakes by operating on the basis of CTA arachnoid cysts. J Neuropathol Exp Neurol 40:61–83, 1981. alone, we are gradually moving back toward DSA, which has 5. Shapiro KN, Swift DM: Intracranial arachnoid cysts, in Tindall GT, Cooper also undergone significant advances during the past few years. PR, Barrow DL (eds): The Practice of Neurosurgery. Baltimore, William & Perhaps the question is not one of “either/or.” Rather, both Wilkins, 1996, vol III. techniques have their own sets of advantages and disadvantages and, in fact, can complement each other in generating valuable

DOI: 10.1227/01.NEU.0000155088.70249.45 diagnostic information, especially in cases of difficult aneurysms, irrespective of whether a surgical or endovascular means of Downloaded from https://academic.oup.com/neurosurgery/article/56/3/E629/2740249 by guest on 28 September 2021 treatment is adopted. Although we agree completely with the Detection of Intracranial Aneurysms with Two- authors’ conclusions about CTA being noninvasive, fast, and dimensional and Three-dimensional Multislice Helical credible in diagnosing ruptured aneurysms, the article stops Computed Tomographic Angiography short of elaborating on the intrinsic pitfalls of the technique, To the Editor: which equally deserve to be highlighted. On the basis of experi- The article by Kangasniemi et al. (4) provides useful insight ence at our institute, we can recommend CTA as an excellent on the first generation of multislice computed tomographic adjuvant but not complete substitute for the “gold standard” angiography (CTA) technology in the detection of intracranial DSA, except in circumstances in which the patient’s rapidly aneurysms. Their informative and timely study reinforces the deteriorating clinical condition is attributable to an expanding fact that the technique of CTA has evolved progressively since aneurysmal . its inception in tandem with developments in high-resolution Kishor A. Choudhari scanning machines and corresponding imaging software. Nidhi Jain Since the late 1990s, we have also been advocates of CTA as Belfast, United Kingdom the sole diagnostic tool for detecting ruptured aneurysms (2, 3). We also use a protocol of subjecting all patients presenting with subarachnoid hemorrhage to CTA first. Digital subtrac- 1. Choudhari KA: Fenestrated anterior cerebral artery. Br J Neurosurg 16:525– tion angiography (DSA) is performed only if the results of 529, 2002. CTA are negative or inconclusive or if the aneurysmal location 2. Choudhari KA, McKinstry S, Kamel H, Fannin T: Efficacy of computed and/or morphology is unusual. The senior author (KAC) has tomographic angiography in the setting of aneurysmal subarachnoid haem- successfully operated on more than 120 patients with ruptured orrhage. Neurosurgery 45:713–714, 1999 (abstr). aneurysms in the past 5 years on the basis of CTA alone 3. Choudhari KA, McKinstry S, Kamel HA, Fannin TF: CT Angiography: Pos- sible non-invasive substitute for conventional angiography in subarachnoid (unpublished data). During the process, however, we have haemorrhage. Br J Neurosurg 14:76, 2000 (abstr). observed certain inherent deficiencies in our approach in sur- 4. Kangasniemi M, Mäkelä T, Koskinen S, Porras M, Poussa K, Hernesniemi JA: gically treating aneurysms on the basis of CTA alone, recent Detection of intracranial aneurysms with two-dimensional and three- technical advances in CTA technology notwithstanding. dimensional multislice helical computed tomographic angiography. Neuro- 54:336–341, 2004. First, the actual pattern of blood flow is much better demon- strated by standard DSA as compared with CTA. This, we be- lieve, is an important requisite for surgery for aneurysms located DOI: 10.1227/01.NEU.0000155089.77873.68 in the region of the AComA. Failure to realize the dominance of any side and to appreciate the precise state of cross-flow across the AComA with CTA has forced us to preserve the AComA Depression in Patients with High-grade Glioma: Results each time surgery is undertaken in this region. This is not always of the Glioma Project mandatory and can be difficult (at times, almost impossible), To the Editor: hence risky. The relatively simpler option of trapping the Litofsky et al. (5) report an impressive incidence of depression AComA for difficult aneurysms ceases to exist unless adequate (93%) in 598 glioma patients enrolled in the Glioma Outcomes filling of respective distal anterior cerebral arteries (A2) from Project. The incidence of mood disorders and the efficacy of their ipsilateral proximal portions (A1) is ensured. In our expe- methods of investigation in cancer patients are controversial. rience, CTA, even with the newer generation of scanning ma- In the literature on cancer and depression, the main issue is chines, does not always provide sufficient information in this the difficulty in distinguishing major depression from mild respect. Conversely, DSA with cross-compression studies can be depression. Even standard screening tools often fail to distin- invaluable. In addition, if there are any anatomic variations in guish between demoralization and major depression. Situa- this region, as there often are, CTA can, in fact, be misleading (1). tional or reactive depression should be considered a normal It is possible to miss a vascular malformation on CTA. Only psychological response to the changes associated with a diag- the flow aneurysms may be detected and erroneously blamed for nosis of cancer. This type of depression is essentially psycho- the hemorrhage, thereby missing the actual culprit. Even with logical in nature rather than physiological and is more respon- the best-quality CTA, the perforators around the aneurysm may sive to supportive psychotherapy than medication (1).

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