Idiopathic bilateral stenosis of the foramina of Monro treated using endoscopic foraminoplasty and septostomy

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Hydrocephalus caused by stenosis of the foramen of Monro is rare. The authors describe a 28-year-old female patient with bilateral foraminal stenosis treated using endoscopic septostomy and unilateral foraminal balloon plasty (foraminoplasty). The patient's hydrocephalus and symptoms resolved postoperatively. Endoscopic strategies may be employed as first-line therapy in this condition.

Abbreviation used in this paper: TORCH = toxoplasmosis/toxoplasma gondii, other infections, rubella, cytomegalovirus, and herpes simplex virus.

Hydrocephalus caused by stenosis of the foramen of Monro is rare. The authors describe a 28-year-old female patient with bilateral foraminal stenosis treated using endoscopic septostomy and unilateral foraminal balloon plasty (foraminoplasty). The patient's hydrocephalus and symptoms resolved postoperatively. Endoscopic strategies may be employed as first-line therapy in this condition.

Hydrocephalus secondary to stenosis of the foramen of Monro is rare.18 Foraminal stenosis has been attributed to infectious origins (particularly TORCH infections) causing inflammation and subsequent scarring in the region,2,3 congenital atresia,7,9,19,22,24 vascular malformations,23 and neoplastic processes,7 particularly thalamic or intraventricular tumors. Unilateral hydrocephalus from foraminal stenosis may be treated using shunting7 or endoscopic procedures.14 We report a case of idiopathic bilateral stenosis of the foramina of Monro causing obstructive hydrocephalus and describe an endoscopic technique used to treat this rare condition.

Case Report

History and Presentation

This patient was a 28-year-old woman with a 3-year history of headaches who presented with episodic near syncope and progressive lethargy. She had no history of meningitis or other inflammatory conditions. There were no focal neurological deficits on examination. The patient was normocephalic. Her fundoscopic examination was notable for papilledema. An MR image revealed enlargement of both lateral ventricles and a very small third and fourth ventricle consistent with stenosis of both foramina of Monro and patency of the cerebral aqueduct and fourth ventricular outlet (Fig. 1A and B). The patient began to receive acetazolamide, which provided some headache relief, but her symptoms returned shortly. She was referred to our center for further evaluation and treatment. After discussing the risks and benefits of various treatment options with the patient, including shunt placement and continued medical management, we recommended a Monro foraminoplasty and septostomy.

Fig. 1.
Fig. 1.

Preoperative axial T2-weighted MR imaging sequences (A and B) show enlargement of bilateral lateral ventricles accompanied by small third and fourth ventricles suggesting stenosis at the level of both foramina of Monro. Postoperative axial MR imaging (C and D) shows smaller ventricular caliber and redistribution of CSF along the cortical subarachnoid spaces.

Operation

The patient was positioned supine on the operating table and placed in a Mayfield head holder. Using frameless stereotactic guidance, an incision and bur hole were made on the left coronal suture approximately 2 cm off midline, and a trajectory was planned toward the ipsilateral foramen of Monro. The left side was used in this instance because the right ventricle was slightly larger than the left, enabling a safer penetration into the contralateral frontal horn during septostomy.

After the dura was coagulated and incised, a 0° Aesculap MINOP endoscope with a Xenon light source was passed through a 14 Fr introducer sheath into the left frontal horn (Video 1).

Video 1. Clip showing the Monro foraminoplasty. Click here to view with Windows Media Player. Click here to view with Quicktime.

We confirmed our location by identifying the septum on the right side of our field. We visualized the left foramen on Monro, which was occluded by a thin, translucent membrane (Fig. 2). The choroid plexus appeared normal and there was no evidence of tumor.

Fig. 2.
Fig. 2.

Intraoperative endoscopic photo showing the thalamostriate and septal veins merging posterior to the left foramen of Monro, which is occluded by a thin, translucent membrane. The choroid plexus appears normal and there is no evidence of tumor.

Using bipolar and monopolar electrocautery, we made a large fenestration in the septum pellucidum and entered the right frontal horn through this septostomy (Fig. 3). We inspected the right foramen of Monro and found that it was not patent.

Fig. 3.
Fig. 3.

Intraoperative endoscopic photos showing a septostomy performed (left) and a large defect in the septum pellucidum that now allows communication between the left and right lateral ventricles (right).

We removed the endoscope and switched to a 30° angled scope. We maneuvered into the left frontal horn again, tracing the choroid plexus to the occluded left foramen of Monro. The 5 Fr Fogarty catheter was advanced into this foramen and balloon-dilated the opening (Fig. 4). After the foramenoplasty, the orifice was patent, the third ventricle was visualized, and a brisk flow of CSF was noted. The endoscope was slowly removed and no bleeding was noted. A third ventriculostomy was not performed, as the cerebral aqueduct and fourth ventricular outflow were patent.

Fig. 4.
Fig. 4.

Intraoperative endoscopic photos showing the Fogarty catheter inserted into the left foramen of Monro (left), which was inflated to disrupt the membranous occlusion of this orifice and restore CSF flow into the third ventricle (right).

Postoperative Course

The patient was observed in the neurosurgical intensive care unit overnight and discharged on postoperative Day 2 without any complications. At the 1-month follow-up visit, the patient's headaches and papilledema had resolved. She underwent MR imaging (Fig. 1C and D), which showed smaller ventricular caliber and expansion of the cortical subarachnoid spaces. She reported no headaches 1 year after surgery.

Discussion

Stenosis of the foramen of Monro, either unilateral or bilateral, is a rare occurrence.2,10,22 Infectious, neoplastic, vascular, and developmental causes have been implicated in this type of stenosis.2–4,6,7,9,10,12,17–19,22–24 Our patient had no history of an infectious condition, and there was no evidence of a neoplastic or vascular process on MR imaging or intraoperatively.

Endoscopic techniques have proven safe and effective in treating hydrocephalus caused by foraminal stenosis,14 and spare the patient the high lifelong cumulative risk of shunt failure.20 Fenestration of the foramen of Monro13 or septum pellucidum5 have been used for unilateral foraminal stenosis. In a series of 32 patients who underwent septostomy for isolated lateral ventricular hydrocephalus, the initial success rate was 53%, which increased to 81% with repeat procedures.1 Procedural risks include the inability to fenestrate the septum and intraventricular hemorrhage; these risks appear to be increased in the presence of distorted anatomy or a thickened septum.1 Compared with septostomy, there are no large series describing outcomes of foraminoplasty. However, 10 of 13 patients combined from recent series had acceptable outcome without the need for a shunt after the procedure (Table 1).8,11,13,15,16,21,25 Foraminoplasty may be performed safely in the presence of a thin avascular membrane covering the foramen.13 However, if the foramen is atretic or obscured, there is increased risk of injury to the fornix. In this instance, shunting6 or septostomy13 may be performed.

TABLE 1:

Studies reporting the outcome of endoscopic fenestration of the foramen of Monro*

Authors & YearAgePostop Ventricular SizeFollow-Up Period (no shunt required)Postfenestration Day (shunt required)
Mohanty et al., 1996NRNRNR
Oi et al., 19997 yrsunchanged5 yrs
Kumar, 1999NRNRNR
NRNRNR
Wong & Lee, 20002 yrsNR5
9 yrsNR14 mos
Freudenstein et al., 200237 yrsunchanged3
62 yrsdecreased1 yr
Spennato et al., 20072 yrsNR27 mos
5 yrsNR12 mos
8 yrsNR26 mos
Oi & Enchev, 200810 daysdecreased1 yr
11 daysdecreased5 yrs

* NR = not reported.

By performing a septostomy and unilateral foraminoplasty, we were able to restore CSF flow in a patient with bilateral obstructions at the foramina of Monro. We did not believe an endoscopic third ventriculostomy was indicated because the third ventricle was small and there was no evidence of outflow obstruction. Postoperatively, the patient's symptoms resolved, her fundoscopic examination results returned to normal, and her MR imaging results showed improvement in ventricular size with redistribution of the CSF along the cortical subarachnoid spaces. Potential complications of this endoscopic approach include injury to the nearby fornix, deep veins, or internal capsule, but are rare in our experience. In the presence of favorable anatomy, hydrocephalus caused by bilateral stenosis of the foramina of Monro may be effectively treated with endoscopic septostomy and unilateral foraminoplasty.

Disclosure

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author contributions to the study and manuscript preparation include the following. Conception and design: all authors. Acquisition of data: all authors. Analysis and interpretation of data: all authors. Drafting the article: all authors. Critically revising the article: all authors. Reviewed final version of the manuscript and approved it for submission: all authors. Administrative/technical/material support: all authors. Study supervision: Harter.

References

  • 1

    Aldana PRKestle JRBrockmeyer DLWalker ML: Results of endoscopic septal fenestration in the treatment of isolated ventricular hydrocephalus. Pediatr Neurosurg 38:2862942003

    • Search Google Scholar
    • Export Citation
  • 2

    Alexander E JrBotterell EH: Unilateral hydrocephalus resulting from occlusion of foramen of Monro; complication of radical removal of brain abscess. J Neurosurg 6:1972061949

    • Search Google Scholar
    • Export Citation
  • 3

    Baumann BDanon LWeitz RBlumensohn RSchonfeld TNitzan M: Unilateral hydrocephalus due to obstruction of the foramen of Monro: another complication of intrauterine mumps infection?. Eur J Pediatr 139:1581591982

    • Search Google Scholar
    • Export Citation
  • 4

    Bhagwati S: A case of unilateral hydrocephalus secondary to occlusion of one foramen of Monro. J Neurosurg 21:2262291964

  • 5

    Boyar BIldan FBagdatoglu HCetinalp EKaradayi A: Unilateral hydrocephalus resulting from occlusion of foramen of Monro: a new procedure in the treatment: stereotactic fenestration of the septum pellucidum. Surg Neurol 39:1101141993

    • Search Google Scholar
    • Export Citation
  • 6

    Dastgir GAwad ASalam AAttia M: Unilateral hydrocephalus due to foramen of monro stenosis. Minim Invasive Neurosurg 49:1841862006

    • Search Google Scholar
    • Export Citation
  • 7

    Dorwling-Carter DScherpereel BBaudrillart JCOmez FLejeune JPRousseaux P: [Unilateral non-tumor hydrocephalus in children. Atresia of the foramen of Monro?]. Neurochirurgie 33:1291341987. (Fr)

    • Search Google Scholar
    • Export Citation
  • 8

    Freudenstein DDuffner FKrapf HWagner AGrote EH: Neuroendoscopic treatment of idiopathic occlusion of the foramen of Monro in adults—two case reports. Neurol Med Chir (Tokyo) 42:81852002

    • Search Google Scholar
    • Export Citation
  • 9

    Gaston BMJones BE: Perinatal unilateral hydrocephalus. Atresia of the foramen of Monro. Pediatr Radiol 19:3283291989

  • 10

    Husag LWieser HGProbst C: [Unilateral hydrocephalus due to membranous occlusions of the foramen of Monro (author's transl).]. Acta Neurochir (Wien) 33:1832121976. (Ger)

    • Search Google Scholar
    • Export Citation
  • 11

    Kumar R: Unilateral hydrocephalus in paediatric patients, a trial of endoscopic fenestration. Neurol India 47:2822851999

  • 12

    Miyahara NSaito YTabuchi SWatanabe TMaegaki YOhno K: [Unilateral hydrocephalus due to congenital stenosis of foramen of Monro—observation of the slowly progressive ventricular dilatation during asymptomatic period.]. No To Hattatsu 40:4894912008. (Jpn)

    • Search Google Scholar
    • Export Citation
  • 13

    Mohanty ADas BSSastry Kolluri VRHedge T: Neuro-endoscopic fenestration of occluded foramen of Monro causing unilateral hydrocephalus. Pediatr Neurosurg 25:2482511996

    • Search Google Scholar
    • Export Citation
  • 14

    Oertel JMBaldauf JSchroeder HWGaab MR: Endoscopic options in children: experience with 134 procedures. Clinical article. J Neurosurg Pediatr 3:81892009

    • Search Google Scholar
    • Export Citation
  • 15

    Oi SEnchev Y: Neuroendoscopic foraminal plasty of foramen of Monro. Childs Nerv Syst 24:9339422008

  • 16

    Oi SHidaka MHonda YTogo KShinoda MShimoda M: Neuroendoscopic surgery for specific forms of hydrocephalus. Childs Nerv Syst 15:56681999

    • Search Google Scholar
    • Export Citation
  • 17

    Oi SMatsumoto S: Pathophysiology of nonneoplastic obstruction of the foramen of Monro and progressive unilateral hydrocephalus. Neurosurgery 17:8918961985

    • Search Google Scholar
    • Export Citation
  • 18

    Oi SYamada HSasaki KMatsumoto S: Atresia of the foramen of Monro resulting in severe unilateral hydrocephalus with subfalcial herniation and infratentorial diverticulum. Neurosurgery 16:1031061985

    • Search Google Scholar
    • Export Citation
  • 19

    Pfeiffer GFriede RL: Unilateral hydrocephalus from early developmental occlusion of one foramen of Monro. Acta Neuropathol 64:75771984

    • Search Google Scholar
    • Export Citation
  • 20

    Sainte-Rose CPiatt JHRenier DPierre-Kahn AHirsch JFHoffman HJ: Mechanical complications in shunts. Pediatr Neurosurg 17:29

    • Search Google Scholar
    • Export Citation
  • 21

    Spennato PCinalli GRuggiero CAliberti FTrischitta VCianciulli E: Neuroendoscopic treatment of multiloculated hydrocephalus in children. J Neurosurg 106:1 Suppl29352007

    • Search Google Scholar
    • Export Citation
  • 22

    Taboada DAlonso AAlvarez JAParamo CVila J: Congenital atresia of the foramen of Monro. Neuroradiology 17:1611641979

  • 23

    Tien RHarsh GR IVDillon WPWilson CB: Unilateral hydrocephalus caused by an intraventricular venous malformation obstructing the foramen of Monro. Neurosurgery 26:6646661990

    • Search Google Scholar
    • Export Citation
  • 24

    Wilberger JE JrVertosick FT JrVries JK: Unilateral hydrocephalus secondary to congenital atresia of the foramen of Monro. Case report. J Neurosurg 59:8999011983

    • Search Google Scholar
    • Export Citation
  • 25

    Wong TTLee LS: Membranous occlusion of the foramen of Monro following ventriculoperitoneal shunt insertion: a role for endoscopic foraminoplasty. Childs Nerv Syst 16:2132172000

    • Search Google Scholar
    • Export Citation

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Article Information

Address correspondence to: Stephen P. Kalhorn, M.D., New York University Langone Medical Center, Department of Neurosurgery, Bellevue Hospital, 462 First Avenue, Room 7S4, New York, New York 10016. email: kalhorn@gmail.com.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Preoperative axial T2-weighted MR imaging sequences (A and B) show enlargement of bilateral lateral ventricles accompanied by small third and fourth ventricles suggesting stenosis at the level of both foramina of Monro. Postoperative axial MR imaging (C and D) shows smaller ventricular caliber and redistribution of CSF along the cortical subarachnoid spaces.

  • View in gallery

    Intraoperative endoscopic photo showing the thalamostriate and septal veins merging posterior to the left foramen of Monro, which is occluded by a thin, translucent membrane. The choroid plexus appears normal and there is no evidence of tumor.

  • View in gallery

    Intraoperative endoscopic photos showing a septostomy performed (left) and a large defect in the septum pellucidum that now allows communication between the left and right lateral ventricles (right).

  • View in gallery

    Intraoperative endoscopic photos showing the Fogarty catheter inserted into the left foramen of Monro (left), which was inflated to disrupt the membranous occlusion of this orifice and restore CSF flow into the third ventricle (right).

References

  • 1

    Aldana PRKestle JRBrockmeyer DLWalker ML: Results of endoscopic septal fenestration in the treatment of isolated ventricular hydrocephalus. Pediatr Neurosurg 38:2862942003

    • Search Google Scholar
    • Export Citation
  • 2

    Alexander E JrBotterell EH: Unilateral hydrocephalus resulting from occlusion of foramen of Monro; complication of radical removal of brain abscess. J Neurosurg 6:1972061949

    • Search Google Scholar
    • Export Citation
  • 3

    Baumann BDanon LWeitz RBlumensohn RSchonfeld TNitzan M: Unilateral hydrocephalus due to obstruction of the foramen of Monro: another complication of intrauterine mumps infection?. Eur J Pediatr 139:1581591982

    • Search Google Scholar
    • Export Citation
  • 4

    Bhagwati S: A case of unilateral hydrocephalus secondary to occlusion of one foramen of Monro. J Neurosurg 21:2262291964

  • 5

    Boyar BIldan FBagdatoglu HCetinalp EKaradayi A: Unilateral hydrocephalus resulting from occlusion of foramen of Monro: a new procedure in the treatment: stereotactic fenestration of the septum pellucidum. Surg Neurol 39:1101141993

    • Search Google Scholar
    • Export Citation
  • 6

    Dastgir GAwad ASalam AAttia M: Unilateral hydrocephalus due to foramen of monro stenosis. Minim Invasive Neurosurg 49:1841862006

    • Search Google Scholar
    • Export Citation
  • 7

    Dorwling-Carter DScherpereel BBaudrillart JCOmez FLejeune JPRousseaux P: [Unilateral non-tumor hydrocephalus in children. Atresia of the foramen of Monro?]. Neurochirurgie 33:1291341987. (Fr)

    • Search Google Scholar
    • Export Citation
  • 8

    Freudenstein DDuffner FKrapf HWagner AGrote EH: Neuroendoscopic treatment of idiopathic occlusion of the foramen of Monro in adults—two case reports. Neurol Med Chir (Tokyo) 42:81852002

    • Search Google Scholar
    • Export Citation
  • 9

    Gaston BMJones BE: Perinatal unilateral hydrocephalus. Atresia of the foramen of Monro. Pediatr Radiol 19:3283291989

  • 10

    Husag LWieser HGProbst C: [Unilateral hydrocephalus due to membranous occlusions of the foramen of Monro (author's transl).]. Acta Neurochir (Wien) 33:1832121976. (Ger)

    • Search Google Scholar
    • Export Citation
  • 11

    Kumar R: Unilateral hydrocephalus in paediatric patients, a trial of endoscopic fenestration. Neurol India 47:2822851999

  • 12

    Miyahara NSaito YTabuchi SWatanabe TMaegaki YOhno K: [Unilateral hydrocephalus due to congenital stenosis of foramen of Monro—observation of the slowly progressive ventricular dilatation during asymptomatic period.]. No To Hattatsu 40:4894912008. (Jpn)

    • Search Google Scholar
    • Export Citation
  • 13

    Mohanty ADas BSSastry Kolluri VRHedge T: Neuro-endoscopic fenestration of occluded foramen of Monro causing unilateral hydrocephalus. Pediatr Neurosurg 25:2482511996

    • Search Google Scholar
    • Export Citation
  • 14

    Oertel JMBaldauf JSchroeder HWGaab MR: Endoscopic options in children: experience with 134 procedures. Clinical article. J Neurosurg Pediatr 3:81892009

    • Search Google Scholar
    • Export Citation
  • 15

    Oi SEnchev Y: Neuroendoscopic foraminal plasty of foramen of Monro. Childs Nerv Syst 24:9339422008

  • 16

    Oi SHidaka MHonda YTogo KShinoda MShimoda M: Neuroendoscopic surgery for specific forms of hydrocephalus. Childs Nerv Syst 15:56681999

    • Search Google Scholar
    • Export Citation
  • 17

    Oi SMatsumoto S: Pathophysiology of nonneoplastic obstruction of the foramen of Monro and progressive unilateral hydrocephalus. Neurosurgery 17:8918961985

    • Search Google Scholar
    • Export Citation
  • 18

    Oi SYamada HSasaki KMatsumoto S: Atresia of the foramen of Monro resulting in severe unilateral hydrocephalus with subfalcial herniation and infratentorial diverticulum. Neurosurgery 16:1031061985

    • Search Google Scholar
    • Export Citation
  • 19

    Pfeiffer GFriede RL: Unilateral hydrocephalus from early developmental occlusion of one foramen of Monro. Acta Neuropathol 64:75771984

    • Search Google Scholar
    • Export Citation
  • 20

    Sainte-Rose CPiatt JHRenier DPierre-Kahn AHirsch JFHoffman HJ: Mechanical complications in shunts. Pediatr Neurosurg 17:29

    • Search Google Scholar
    • Export Citation
  • 21

    Spennato PCinalli GRuggiero CAliberti FTrischitta VCianciulli E: Neuroendoscopic treatment of multiloculated hydrocephalus in children. J Neurosurg 106:1 Suppl29352007

    • Search Google Scholar
    • Export Citation
  • 22

    Taboada DAlonso AAlvarez JAParamo CVila J: Congenital atresia of the foramen of Monro. Neuroradiology 17:1611641979

  • 23

    Tien RHarsh GR IVDillon WPWilson CB: Unilateral hydrocephalus caused by an intraventricular venous malformation obstructing the foramen of Monro. Neurosurgery 26:6646661990

    • Search Google Scholar
    • Export Citation
  • 24

    Wilberger JE JrVertosick FT JrVries JK: Unilateral hydrocephalus secondary to congenital atresia of the foramen of Monro. Case report. J Neurosurg 59:8999011983

    • Search Google Scholar
    • Export Citation
  • 25

    Wong TTLee LS: Membranous occlusion of the foramen of Monro following ventriculoperitoneal shunt insertion: a role for endoscopic foraminoplasty. Childs Nerv Syst 16:2132172000

    • Search Google Scholar
    • Export Citation

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