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Donald Horton and Michael Pollay

T he flow characteristics of the first commercially available anti-siphon valve, designed as an anti-siphon device (ASD) for ventricular shunting, were reported by Portnoy, et al. , 15 in 1973. In the present paper, we discuss a similar device that has some advantages over the earlier ASD when used in conjunction with presently available differential-pressure valves for the treatment of hydrocephalus. The necessity for control of cerebrospinal fluid (CSF) outflow from the ventricular system while the patient is in an upright position has been appreciated for

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Mahmood Hassan, Sotaro Higashi and Junkoh Yamashita

cranial sutures. 15 Furthermore, our recent study of cerebral blood flow in patients whose shunts had differential-pressure valves revealed abnormal intracranial hemodynamics. 9 To relieve these complications, siphon-reducing devices have been developed. Portnoy, et al. , 19 developed the antisiphon device (ASD) in 1973. A new siphon-reducing device, the siphon-control device (SCD), was reported by Horton and Pollay 11 with some improvements over ASD in construction. The Delta valve, in which SCD is incorporated with differential-pressure valve, was developed in

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distinguished the differences between the antisiphon device (ASD) and the Delta valve; furthermore, they erroneously suggest that the Delta valve is equivalent to the ASD referred to in the article by da Silva and Drake. 1 In the erect position, the ASD tends to increase resistance to flow to a level that stops the flow of cerebrospinal fluid (CSF). This is due to the ASD design, which has an inlet-to-outlet surface area ratio of only 8:1. Specifically, the 20:1 ratio of the Delta valve eliminates the siphoning effect while only increasing the resistance to flow in the erect

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Sagun Tuli, James Drake, Jerry Lawless, Melanie Wigg and Maria Lamberti-Pasculli

. Cambridge, Mass: Blackwell Science, 1995, pp 123–192 18. Griebel R , Khan M , Tan L : CSF shunt complications: an analysis of contributory factors. Childs Nerv Syst 1 : 77 – 80 , 1985 Griebel R, Khan M, Tan L: CSF shunt complications: an analysis of contributory factors. Childs Nerv Syst 1: 77–80, 1985 19. Gruber R , Jenny P , Herzog B : Experiences with the anti-siphon device (ASD) in shunt therapy of pediatric hydrocephalus. J Neurosurg 61 : 156 – 162 , 1984 Gruber R, Jenny P, Herzog B: Experiences with the anti-siphon device (ASD) in shunt

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Bryan Rankin Payne, Dheerendra Prasad, György Szeifert, Melita Steiner and Ladislau Steiner

of Center) No. of Patients No. of Tumors Total No. Total W/ ASD W/O ASD Mori, et al., 1998 (Pittsburgh, PA) 35 52 39 26 65 10 8 11 5 in 11 patients 15 in 24 patients Schöggl, et al., 1998 (Vienna, Austria) 23 44 33 0 97 † 3 † 0 11 7 in 13 patients 25 in 10 patients present study (Charlottesville, VA) 21 36 23 4 96 0 0 8 4 in 13 patients 19 in 8 patients total 79 132 105 11 75 5 3 ‡ 10 5.4 18.1 * Among patients in whom follow-up imaging was available. Abbreviation: ASD = active SD. † At 12 weeks. ‡ Two of 58 patients who died. Gamma surgery is effective in

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Bo Lundkvist, Anders Eklund, Bo Kristensen, Markku Fagerlund, Lars-Owe D. Koskinen and Jan Malm

systems in an in vivo setting. 8, 14, 21 Recently, we introduced a CSF infusion method to be used pre- and postoperatively in patients with communicating hydrocephalus. This in vivo technique makes it possible to assess CSF hydrodynamics postoperatively and to determine the properties of the shunt system, including the degree of gravity-induced CSF flow. 21 The traditional differential pressure valves are sensitive to body posture, which may induce overdrainage due to siphoning. Valves with ASDs may decrease these complications, but inadequate drainage of CSF due to

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Elizabeth Lajeunie, Uli Barcik, John A. Thorne, Vincent El Ghouzzi, Marie Bourgeois and Dominique Renier

2000 10 45 (7 yrs) rt clubhand, hypoplastic radius retroesophageal subclavian artery, Rieger syndrome 16 F 2000 10 79 (10 mos) clubhands, agenesis of radius septum cyst, hypertrophic clitoris 17 M 2500 NO NA campodactyly ASD, hypospadias, tracheomalacia * ASD = atrial septal defect; NA = not available; NO = no operation; VSD = ventricular septal defect. † Additional involvement of one coronal suture. ‡ Additional involvement of sagittal suture. Birth weights were within the expected

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Jürgen Boschert, Dieter Hellwig and Joachim K. Krauss

, somnolence, Parinaud syndrome; emergency 44 mos unremarkable  VP  shunt dysfunction w/ acute hydrocephalus on CT 2 21, M obstruction of 4th ventricle 1.2 postural HA; overdrainage w/ ventricular collapse elective, ventricular 39 mos unremarkable  outlet after removal of  on CT  dilation  cerebellar astrocytoma; VP w/ ASD 3 30, F aqueductal stenosis; VP 14 slowly progressive somnolence, gait disturbance, elective 36 mos unremarkable  urinary incontinence

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Shinji Kimura, John R. Hesselink, Steven R. Garfin, Yoichi Kawaji, Kazuhiro Hasegawa and Alan R. Hargens

.K.) determined all the axial lines on the sagittal images. On T 2 -weighted axial images AP diameter, transverse diameter, and CSA for the spinal cord and the dural sac were measured. Additional measurements included the following: 1) the ASD from the anterior dural margin to the anterior aspect of the spinal cord; and 2) the PSD from the posterior margin of the spinal cord to the posterior dural membrane. These measurements provided an estimate of the distance of the posterior movement of the spinal cord when we subtracted the distances on the axial loaded images from those

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Sepehr Sani, Kirk W. Jobe and Richard W. Byrne

to the skull. N Engl J Med 345: 339, 2001 9. Spiers ASD : Attempted suicide or hitting the nail on the head. Case report. J Fla Med Assoc 81 : 822 – 823 , 1994 Spiers ASD: Attempted suicide or hitting the nail on the head. Case report. J Fla Med Assoc 81: 822–823, 1994 10. Tancioni F , Gaetani P , Pugliese R , Rodriguez Y , Baena R : Intracranial nail. A case report. J Neurosurg Sci 38 : 239 – 243 , 1994 Tancioni F, Gaetani P, Pugliese R, Rodriguez Y, Baena R