Endoscopic third ventriculostomy

Endoscopic third ventriculostomy (ETV) is a surgical procedure for treatment of hydrocephalus in which an opening is created in the floor of the third ventricle using an endoscope placed within the ventricular system through a burr hole. This allows the cerebrospinal fluid to flow directly to the basal cisterns, thereby shortcutting any obstruction.[1]

Indications

The ETV procedure is used as an alternative to a cerebral shunt[2] mainly to treat certain forms of noncommunicating obstructive hydrocephalus (such as aqueductal stenosis), but since the ETV was introduced as an accepted treatment modality the range of etiologies for which it is used has grown significantly. Whereas at first it was almost exclusively performed in patients with noncommunicating obstructive hydrocephalus (e.g. aqueductal stenosis or intracerebral tumor), in the present day patients with communicating obstructive hydrocephalus (e.g. post intracranial hemorrhage or post intracranial infection) also may be eligible for treatment by means of ETV.

Complications

A huge advantage of placing an endoscopic third ventriculostomy over implantation of a cerebrospinal fluid shunt is the absence of a foreign body. A shunt has risk of infection and failure for which subsequent surgery is needed. Complications of ETV include hemorrhage (the most severe being due to basilar artery rupture), injury to neural structures (e.g. hypothalamus, pituitary gland or fornix of the brain), and late sudden deterioration.[3] Infection, hematoma, and cerebrospinal fluid leaks may present in the direct postoperative period.

Failure of treatment

Failure of the ETV occurs. This can be due to occlusion of the ventriculostomy (e.g. closure of the ventriculostomy, formation of subarachnoid membranes in the pontine cistern or other mechanisms). Although 60 - 90% of failures occur in the first few months after treatment, long-term failure also occurs (failures occurring after 7 years have been reported).[4] In a very small subgroup of patients a complication of ETV can be rapid late deterioration.[5] The mechanism is not clear.

Alternative treatment

When it is not possible to perform an ETV for different reasons, an alternative treatment is opening the lamina terminalis anterior to the third ventricle.[6] The effectiveness of this approach is not certain.[7]

The surgical treatment options for hydrocephalus are, as previously mentioned, implantation of a cerebral shunt and ETV. Especially in the youngest age group (younger than two years of age) it remains uncertain what is the superior treatment modality. Currently, a large international, multicenter study is conducted to address this issue. Patients under the age of two, diagnosed with aqueductal stenosis without a history of preterm birth or other associated brain anomalies are being included (International Infant Hydrocephalus Study).[8][9]

ETV combined with choroid plexus cauterization

There is a discussion regarding the additional benefit of combining endoscopic third ventriculostomy with choroid plexus cauterization. This combined procedure is referred by the abbreviation "ETV/CPC" and has also been called the "Warf Procedure"[10] after Dr. Benjamin Warf. There have been research studies published about the experience of authors with this procedure. The lion's share of the data that show favorable results is reported on patients in Africa.[11] More recent studies from research groups in Western countries also show that the combination of ETV with choroid plexus cauterization seems to be effective, safe, and durable,[12] and that predictions for success are similar to those of ETV alone.[13] The degree of choroid plexus cauterization in infants might be dependent on the experience of the neurosurgeon (learning curve) and thus surgeons training might improve results.[14]

Prediction of ETV success

The chances of success of treatment of a pediatric patient can be calculated using the ETV success score (ETVSS).[15][16][17] The ETVSS is derived from patient age, etiology of hydrocephalus and history of previous cerebrospinal fluid shunt (e.g. ventriculo-peritoneal shunt). The percentage probability of ETV success = Age score + Etiology score + Previous shunt score. A two years old patient with hydrocephalus due to aqueductal stenosis, without previous shunt would have an 80% chance of success (40 for age + 30 for etiology + 10 for no previous shunt = 80).

ETVSS table[15]

Score Age Etiology Previous Shunt
0 < 1 month Post-infectious Previous shunt
10 1 month to < 6 months No previous shunt
20 Myelomeningocele, intraventricular hemorrhage, non-tectal brain tumor
30 6 months to < 1 year Aqueductal stenosis, tectal brain tumor, other etiology
40 1 year to < 10 years
50 ≥ 10 years

Second ETV

After a patient gets readmitted with recurrend clinical and radiological symptomatology of hydrocephalus, it is unclear what the next step in treatment should be. Implantation of a cerebrospinal fluid shunt or repeat ETV. Data suggest that a second ETV might be worthwhile if implantation of cerebrospinal fluid shunt can be avoided.[18][19]

Training ETV

In most countries and neurosurgical centres, the ETV procedure is part of the basic neurosurgery training program. For the sake of teaching and practicing, various simulation models have been developed. Virtual reality simulators,[20] and synthetic simulators.[21][22] This allows neurosurgical trainees to practice skills in a low-risk environment. The technical skill and competency of a trainee can be evaluated using the Neuro-Endoscopic Ventriculostomy Assessment Tool (NEVAT).[23]

References

  1. ↑ Kahle, Kristopher T; Kulkarni, Abhaya V; Limbrick, David D; Warf, Benjamin C. "Hydrocephalus in children". The Lancet. doi:10.1016/s0140-6736(15)60694-8.
  2. ↑ Hydrocephalus and Treatment: Shunts and Endoscopic Third Ventriculostomy, AboutKidsHealth.ca
  3. ↑ Bouras, T.; Sgouros, S. (2013). "Complications of endoscopic third ventriculostomy". Journal of Neurosurgery 79 (2 Supple): e9–12. doi:10.1016/j.wneu.2012.02.014. PMID 22381818.
  4. ↑ Vulcu, Sonja; Eickele, Leonie; Cinalli, Giuseppe; Wagner, Wolfgang; Oertel, Joachim (2015-07-31). "Long-term results of endoscopic third ventriculostomy: an outcome analysis". Journal of Neurosurgery: 1–7. doi:10.3171/2014.11.jns14414.
  5. ↑ Drake, J.; Chumas, P.; Kestle, J.; Pierre-Kahn, A.; Vinchon, M.; Brown, J.; Pollack, I.F.; Arai, H. (2006). "Late rapid deterioration after endoscopic third ventriculostomy: additional cases and review of the literature.". Journal of Neurosurgery 105 (2 Supple): 118–26. doi:10.3171/ped.2006.105.2.118. PMID 16922073.
  6. ↑ Oertel, Joachim M. K.; Vulcu, Sonja; Schroeder, Henry W. S.; Konerding, Moritz A.; Wagner, Wolfgang; Gaab, Michael R. (2010). "Endoscopic transventricular third ventriculostomy through the lamina terminalis". Journal of Neurosurgery 113 (6): 1261–9. doi:10.3171/2010.6.JNS09491. PMID 20707616.
  7. ↑ Komotar, Ricardo J.; Hahn, David K.; Kim, Grace H.; Starke, Robert M.; Garrett, Matthew C.; Merkow, Maxwell B.; Otten, Marc L.; Sciacca, Robert R.; Connolly, E. Sander (2009). "Efficacy of lamina terminalis fenestration in reducing shunt-dependent hydrocephalus following aneurysmal subarachnoid hemorrhage: A systematic review". Journal of Neurosurgery 111 (1): 147–54. doi:10.3171/2009.1.JNS0821. PMID 19284236.
  8. ↑ Sgouros, S.; Kulkharni, A. V.; Constantini, S. (2005-10-15). "The international infant hydrocephalus study: concept and rational". Child's Nervous System 22 (4): 338–345. doi:10.1007/s00381-005-1253-y. ISSN 0256-7040.
  9. ↑ Constantini, S.; Sgouros, S.; Kulkarni, A. (2013). "Neuroendoscopy in the youngest age group.". World Neurosurgery 79 (2 Supple): S23.e1–11. doi:10.1016/j.wneu.2012.02.003. PMID 22381849.
  10. ↑ "Neurosurgeons challenged to eliminate all infant deaths from hydrocephalus". EurekAlert. Retrieved 14 January 2016.
  11. ↑ Warf, B.C.; Tracy, S.; Mugamba, J. (2012). "Long-term outcome for endoscopic third ventriculostomy alone or in combination with choroid plexus cauterization for congenital aqueductal stenosis in African infants". Journal of Neurosurgery. Pediatrics 10 (2): 108–11. doi:10.3171/2012.4.PEDS1253. PMID 22747094.
  12. ↑ Stone, S.S.; Warf, B.C. (2014). "Combined endoscopic third ventriculostomy and choroid plexus cauterization as primary treatment for infant hydrocephalus: a prospective North American series". Journal of Neurosurgery. Pediatrics 14 (5): 439–46. doi:10.3171/2014.7.PEDS14152. PMID 25171723.
  13. ↑ Riva-Cambrin, Jay. "ETV+CPC Success and Evolving Indications over Time: A Prospective HCRN Study". Hydrocephalus Cinical Research Network. Retrieved 7 March 2016.
  14. ↑ Kulkarni, A.V.; Riva-Cambrin, J.; Browd, S.R.; Drake, J.M.; Holubkov, R.; Kestle, J.R.; Limbrick, D.D.; Rozzelle, C.J.; Simon, T.D.; Tamber, M.S.; Wellons, J.C.3rd.; Whitehead, W.E.; Hydrocephalus Clinical Research Network. (2014). "Endoscopic third ventriculostomy and choroid plexus cauterization in infants with hydrocephalus: a retrospective Hydrocephalus Clinical Research Network study". Journal of Neurosurgery. Pediatrics 14 (3): 224–9. doi:10.3171/2014.6.PEDS13492. PMID 24995823.
  15. 1 2 Kulkarni, A.V.; Drake, J.M.; Mallucci, C.L.; Sgouros, S.; Roth, J.; Constantini, S.; Canadian Pediatric Neurosurgery Study Group (2009). "Endoscopic third ventriculostomy in the treatment of childhood hydrocephalus". Journal of Pediatrics 155 (2): 254–9. doi:10.1016/j.jpeds.2009.02.048. PMID 19446842.
  16. ↑ Durnford, Andrew J.; Kirkham, Fenella J.; Mathad, Nijaguna; Sparrow, Owen C. E. (2011-11-01). "Endoscopic third ventriculostomy in the treatment of childhood hydrocephalus: validation of a success score that predicts long-term outcome". Journal of Neurosurgery: Pediatrics 8 (5): 489–493. doi:10.3171/2011.8.PEDS1166. ISSN 1933-0707.
  17. ↑ Breimer, G. E.; Sival, D. A.; Brusse-Keizer, M. G. J.; Hoving, E. W. (2013-05-05). "An external validation of the ETVSS for both short-term and long-term predictive adequacy in 104 pediatric patients". Child's Nervous System 29 (8): 1305–1311. doi:10.1007/s00381-013-2122-8. ISSN 0256-7040.
  18. ↑ Peretta, P.; Cinalli, G.; Spennato, P.; Ragazzi, P.; Rugierro, C.; Aliberti, F.; Carlino, C.; Cianciulli, E. (2009). "Long-term results of a second endoscopic third ventriculostomy in children: retrospective analysis of 40 cases.". Neurosurgery 65 (3): 539–47. doi:10.1227/01.NEU.0000350228.08523.D1. PMID 19687699.
  19. ↑ Marano, Paul J.; Stone, Scellig S. D.; Mugamba, John; Ssenyonga, Peter; Warf, Ezra B.; Warf, Benjamin C. (2015-02-06). "Reopening of an obstructed third ventriculostomy: long-term success and factors affecting outcome in 215 infants". Journal of Neurosurgery: Pediatrics 15 (4): 399–405. doi:10.3171/2014.10.peds14250.
  20. ↑ Choudhury, N.; Gelinas-Phaneuf, F.; Delorme, S.; Del Maestro, R. (2013). "Fundamentals of neurosurgery: virtual reality tasks for training and evaluation of technical skills.". World Neurosurgery 80 (5): e9–19. doi:10.1016/j.wneu.2012.08.022. PMID 23178917.
  21. ↑ Breimer, G.E.; Bodani, V.; Looi, T.; Drake, J.M. (2015). "Design and evaluation of a new synthetic brain simulator for endoscopic third ventriculostomy.". Journal of Neurosurgery. Pediatrics 15 (1): 82–8. doi:10.3171/2014.9.PEDS1447. PMID 25360853.
  22. ↑ Zymberg, S.; Vaz-Guimaraes Filho, F.; Lyra, M. (2010). "Neuroendoscopic training: presentation of a new real simulator.". Minimally Invasive Neurosurgery 53 (1): 44–6. doi:10.1055/s-0029-1246169. PMID 20376746.
  23. ↑ Breimer, Gerben E.; Haji, Faizal A.; Hoving, Eelco W.; Drake, James M. (2015-05-01). "Development and content validation of performance assessments for endoscopic third ventriculostomy". Child's Nervous System 31 (8): 1247–1259. doi:10.1007/s00381-015-2716-4. ISSN 0256-7040.

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