Spontaneous CSF rhinorrhea: Prevalence of multiple simultaneous skull base defects Seth M. Lieberman, M.D.,1 Si Chen, M.D.,2 Daniel Jethanamest, M.D.,1 and Roy R. Casiano, M.D.2

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ABSTRACT

Background: Spontaneous cerebrospinal fluid (CSF) leaks are caused by intracranial hypertension. Given this underlying etiology, patients may be at risk for developing multiple skull base defects. Objective: The purpose of our study is to present the prevalence of multiple simultaneous skull base defects in patients with spontaneous CSF rhinorrhea. Methods: We performed a retrospective chart review in a tertiary care practice of 44 consecutive patients with spontaneous CSF rhinorrhea who underwent endoscopic repair by the senior author (R.R.C.) to determine the prevalence of having multiple simultaneous skull base defects identified at the time of surgery. We defined this as two or more bony defects identified endoscopically with intact intervening bone with or without soft tissue prolapse into the nasal cavity or paranasal sinus cavity. Results: Eight of 44 patients (18.2%) were found to have multiple simultaneous skull base defects. The average body mass index (BMI) of the study population was 34.5 (range, 22.7–59). Conclusion: A significant number of patients with spontaneous CSF rhinorrhea may have more than one skull base defect present at the time of presentation. The clinical significance of this finding in surgical and medical decision making is not clear at this time. (Am J Rhinol Allergy 29, 77–81, 2015; doi: 10.2500/ajra.2015.29.4121)

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n the past, spontaneous cerebrospinal fluid (CSF) leaks were thought to comprise a minority of all CSF leaks. However, this etiology may be on the rise.1 Other etiologies can be categorized as congenital, traumatic, tumor related, and iatrogenic or postsurgical. As Wise and Schlosser point out from their literature review, spontaneous CSF rhinorrhea comprised 3%–5% of all causes before 2000, and 14%–46% of all causes since 2000.1 This finding may result from an increasingly obese population who are at greater risk of spontaneous CSF rhinorrhea, increased recognition of CSF rhinorrhea, increased reporting in the literature, or fewer accidental and traumatic leaks leading to spontaneous leaks carrying a higher percentage of overall leaks. Spontaneous CSF leaks carry the highest recurrence rate of all causes.2,3 This is most likely due to the underlying cause of spontaneous CSF rhinorrhea, which is believed to be a persistent or intermittent elevated intracranial pressure. Over time, the elevated CSF pressures and the hydrostatic pulsatile forces that are transmitted to the skull base eventually erode through thin areas of bone, most commonly the ethmoid roof, cribriform plate, and the lateral recess of the sphenoid sinus.3–5 Given the underlying elevated intracranial pressure in patients with spontaneous CSF rhinorrhea, it would not be surprising if they develop more than one site of skull base erosion. Few have reported on this topic. Lopatin et al. described their series of endoscopic repairs of 21 patients with spontaneous rhinorrhea and mention that one patient (4.8%) had two skull base defects within the sphenoid sinus.6 Woodworth reports that nine of 56 patients (16.1%) had multiple simultaneous CSF leaks in their series of patients with spontaneous CSF rhinorrhea.7 Schlosser and Bolger reported that five of 16 patients (31.2%) that they operated on with spontaneous CSF rhinorrhea had multiple simultaneous skull base defects.3 Our goal was to evaluate our own series of patients with spontaneous CSF rhinorrhea to determine the prevalence of multiple simultaneous skull base defects.

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Department of Otolaryngology, New York University School of Medicine, New York, New York, and 2Department of Otolaryngology, University of Miami-Leonard M. Miller School of Medicine. Miami, Florida Presented at the North American Skull Base Society Meeting, Miami, Florida The authors have no conflicts of interest to declare pertaining to this article Address correspondence to Seth M. Lieberman, M.D., Department of Otolaryngology, New York University, 550 First Avenue, NBV 5E 5, New York, NY 10016 E-mail address: [email protected] Copyright © 2015, OceanSide Publications, Inc., U.S.A.

Study Design

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PATIENTS AND METHODS

This is a retrospective study of consecutive patients who presented to the senior author (R.R.C.) between July 2004 and October 2012 with spontaneous CSF rhinorrhea and underwent surgical repair. The study was approved by the University of Miami Miller School of Medicine Institutional Review Board.

Patient Population Consecutive adult patients (age, more than 18 years) who presented to the senior author with spontaneous CSF rhinorrhea were included in the study. Inclusion criteria included an intraoperative finding of CSF leak or skull base defect. Exclusion criteria included previous head trauma, previous surgery that could account for a CSF leak, or history of neoplasm that could cause a CSF leak. Charts were reviewed for body mass index (BMI), age, sex, and intraoperative findings, including number of skull base defects identified, CSF pressures if performed, use of lumbar drain, use of intrathecal fluorescein, and recurrence. We define multiple simultaneous skull base defects as two or more bony defects identified endoscopically with intact intervening bone with or without soft tissue prolapse into the nasal cavity or paranasal sinus cavity. Statistical analyses were performed using IBM SPSS Statistics for Windows, version 21.0 (IBM Corp., Armonk, NY). Fisher’s exact test or a Student’s t-test were used where appropriate to assess differences among groups with a single versus multiple skull base defects with regards to age, gender, and BMI.

Outcomes Forty-four patients presented to the senior author with spontaneous CSF rhinorrhea between July 2004 and October 2012. Nine were male and 35 were female for a male to female ratio of 1:4. The mean age was 50.9 (range, 32–81). BMI values were available for 40 patients with a mean of 34.5 (range, 22.7–59). Only one of the patients had a normal BMI (less than 25). Eight of the 44 patients (18.2%) had multiple simultaneous skull base defects. There were no statistically significant differences between groups with a single defect versus multiple defects in terms of age (p ⫽ 0.09), sex (p ⫽ 1.0), or BMI (p ⫽ 0.22) (Table 1). The sites of the skull base defects for the group are listed in Table 2. The defect sites for the eight patients with multiple skull base

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Table 1. Patient characteristics

Age (mean, years) % Male BMI (mean, kg/m2)

Overall (n ⴝ 44)

Multiple Defects (n ⴝ 8)

Single Defects (n ⴝ 36)

p-value

50.9 (SD11.6) 20.5% 34.5 (SD 7.0)

57.3 (SD14.7) 12.5% 32.4 (SD 3.3)

49.5 (SD10.5) 22.2% 34.9 (SD 7.5)

0.09* 1.00** 0.22*

* ⫽ Student’s t-test; ** ⫽ Fisher’s exact test, SD ⫽ standard deviation; BMI ⫽ body mass index. Table 2. Site of skull base defect Site of Leak

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Sphenoid Lateral recess Planum sphenoidale Sella Data not available Cribriform Fovea ethmoidalis Frontal sinus Temporal bone

18 14 1 1 2 25 1 2 1

DISCUSSION

Table 3. Defect sites for the eight patients with multiple defects Pt No.

Site of Defect

1 2

Bilateral cribriform L cribriform L tegmen tympani 2 defects of R cribriform Bilateral cribriform 2⫹ defects of L cribriform R posterior table of frontal sinus L lateral sphenoid recess **2 years later presented with R fovea ethmoidalis CSF leak R frontal sinus L sphenoid sinus 2 defects of left lateral sphenoid recess

3 4 5 6

Complication

Anosmia Anosmia Altered sensation in V2 distribution Altered sensation in V2 distribution Altered sensation in V2 distribution Meningitis Frontal lobe abscess Periorbital cellulitis

Cribriform Cribriform Lateral sphenoid recess Lateral sphenoid recess Lateral sphenoid recess Cribriform (h/o shunt) Cribriform Cribriform

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Pt ⫽ patient; CSF ⫽ cerebrospinal fluid; L ⫽ left; R ⫽ right.

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Table 4. Complications and associated site of defect/repair

Site of Defect/Repair

h/o ⫽ history of; V2 ⫽ maxillary division of the trigeminal nerve.

defects are listed in Table 3. All surgical repairs were performed endoscopically with a preoperative intrathecal fluorescein injection used in all cases. CSF pressure measurements were not routinely performed. A lumbar drain was only placed in one patient. This patient had multiple skull base defects. Data of the repair technique were available for 42 patients. Alloderm was used in 39 patients, a mucosal overlay graft was used in two patients, and a bony underlay graft in one patient. Two patients were lost to follow-up, one of whom had multiple defects. The mean follow-up period was 9.2 months (median, five

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This study found that a significant number of patients (18.2%) who present with spontaneous CSF rhinorrhea have multiple skull base defects found at the time of surgical repair. This number falls within the range of 5%–31% that has been previously reported.3,6,7 Considering the likely, underlying pathology of elevated intracranial pressure, the presence of multiple skull base defects is not surprising. Although multiple defects were found in eight patients, the significance of this finding is not clear. Often times, only one of the defects was actively leaking, and the question remains over whether all of the defects must be addressed. In this series, we repaired all of the identified defects. Another question that remains is how many defects we missed because they were not actively leaking or evident on preoperative imaging. We obviously have no way of answering this question from our data, because we did not open all of the sinuses for each patient. Spontaneous CSF rhinorrhea is associated with elevated BMI,7,8 elevated intracranial hypertension,7 empty sella syndrome,9 and arachnoid granulations.9 The etiology is most likely related to exposing thin areas of the skull base with persistent, pulsatile, hydrostatic forces that erode the bone and dura to create a fistula. Psaltis et al.10 have shown differences in skull base thickness between patients with spontaneous CSF leaks and controls. However, whether this contributes to such leaks or is an effect of the underlying pathophysiology remains unknown.10 Given this etiology, it is not surprising that such patients have the highest rates of recurrence, because repair does not fix the underlying problem. Medical management with acetazolamide and surgical management with a shunt are both potential measures that can be used to decrease the pressure and prevent recurrence or development of another leak. Given the underlying etiology of elevated intracranial pressure, these patients may be predisposed to developing multiple areas of bony erosion. One of our patients had a cribriform and a tegmen tympani defect, demonstrating the importance of evaluating for a temporal bone defect in patients presenting with CSF rhinorrhea. The ethmoid roof, cribriform plate, and the lateral sphenoid recess are the most common sites of spontaneous CSF leaks. It is not clear whether this is because these areas are composed of particularly thin bone, whether the hydrostatic forces are greater in these regions, whether arachnoid granulation are more likely to exist in such areas, or some other factor. Defects of the lateral recess of the sphenoid sinus just lateral to maxillary division of trigeminal nerve (V2) have long been attributed to a congenital dehiscence known as Sternberg’s canal. However, this particular etiology has since been challenged.11,12 As Baranano et al. highlight in their article, this site cannot represent Sternberg’s canal, which, based on embryologic development, must be present medial to the superior orbital fissure, and thus medial to V2, whereas defects within the lateral recess of the sphenoid sinus are generally lateral to V2.12 What is more likely is that the bone tends to be thin in patients with a significantly pneumatized lateral recess of

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months; range, 0–60 months). There were no recurrences at the initial site of repair. However, one patient developed a leak at another site that was discovered two years after initial repair. Significant complications are listed in Table 4.

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Figure 1. Right frontal sinus and left sphenoid sinus skull base defects. (A) Endoscopic view of meningocele and leaking fluorescein-stained CSF from skull base defect along posterior table of right frontal sinus. (B) Radiographic correlate of skull base defect seen in A. (C) Endoscopic view of skull base defect of the left lateral sphenoid recess after resection of meningocele. (D) Radiographic correlate of skull base defect seen in C.

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the sphenoid sinus, especially in the area lateral to V2, where the majority of these leaks are found. Our study found an 18.2% rate of multiple bony defects in patients with spontaneous CSF rhinorrhea. We define multiple bony defects as two or more defects of the skull base with intact intervening bone. In our series, some of these defects were quite distant from each other (e.g., frontal and sphenoid sinus) as seen in Fig. 1, while others adjacent (e.g., horizontal lamella and lateral lamella of the cribriform plate) as seen in Fig. 2. The defects in close proximity to one another may be caused by a single meningocele that is exerting pressure on multiple areas of the skull base. What is more important is the significance of this finding. Do the number of defects correlate with BMI? There was no statistically significant difference in BMI between the groups with a single defect and multiple defects. Nor was there any difference in sex and age between the two groups. We would have liked to have evaluated any relationship with multiple defects and recurrence rates, but there were no documented recurrences precluding any meaningful analysis. We also lacked sufficient data of CSF pressures to perform a meaningful analysis. Many of the defects that we identified were not actively leaking at the time. However, we chose to repair all identified defects. It is not clear whether this is necessary in all cases, because we sometimes

found multiple small cribriform defects, and more manipulation in this area will lead to a greater risk of hyposmia/anosmia. Although we did not have most of the scans available to review during our chart review, it would have been useful to assess whether the multiple defects were identifiable on preoperative imaging. For some of the larger defects, it was clearly obvious, but some of the smaller defects could have easily been missed. We routinely use intrathecal fluorescein, which, in our opinion, is extremely helpful in identifying the skull base defect(s). However, we obviously do not know how many we missed intraoperatively that were not actively leaking. If we clinically and radiographically suspected a leak on one side, we would not explore the contralateral side but would generally perform a complete sphenoethmoidectomy on the ipsilateral side. This study has several other limitations. Our follow-up is relatively short considering that intracranial hypertension is a chronic disease, and, unless these patients have a shunt placed, they are at risk of recurrence or developing another leak at a different site for the rest of their lives. This short follow-up, along with the fact that several of the patients traveled from great distances, may contribute to the fact that we have no documented recurrences. Although almost one in five patients had multiple skull base defects, we do not know the prognostic value of this finding and how this information may help guide us in managing these complicated patients. We also do not know the

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Figure 2. Multiple bilateral cribriform skull base defects. (A) Endoscopic view of right horizontal lamella of the cribriform plate with fluorescein-stained meningocele; arrow ⫽ cut edge of middle turbinate. (B) Coronal CT correlate of the defect seen in A. (C) Endoscopic view of skull base defect of right lateral lamella of the cribriform plate with fluorescein-stained CSF leaking out; black arrow ⫽ skull base defect; white arrow ⫽ cut edge of middle turbinate; OC ⫽ olfactory cleft; AEA ⫽ anterior ethmoid artery. (D) Radiographic correlate of the defect seen in C. (E) Meningocele through skull base defect of the left horizontal lamella of the cribriform plate; white arrow ⫽ meningocele/ fluorescein; black arrow ⫽ cut edge of middle turbinate. (F) Radiographic correlate of defect seen in E.

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importance of seeking to find all of these bony defects, if they are not actively leaking, and how aggressive we should be in surgically repairing all defects versus medically managing their intracranial hypertension. Further study is warranted to help answer these questions.

CONCLUSION

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Our study found that among patients undergoing surgery for spontaneous CSF rhinorrhea of the ventral skull base, 18.2% had multiple skull base defects identified at the time of surgery. The clinical significance of this finding in surgical and medical decision making is not clear at this time.

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REFERENCES 1. 2.

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Wise SK, and Schlosser RJ. Evaluation of spontaneous nasal cerebrospinal fluid leaks. Curr Opin Otolaryngol Head Neck Surg 15:28–34, 2007. Shetty PG, Shroff MM, Fatterpekar GM, et al. A retrospective analysis of spontaneous sphenoid sinus fistula: MR and CT findings. Am J Neuroradiol 21:337–342, 2000. Schlosser RJ, and Bolger WE. Significance of empty sella in cerebrospinal fluid leaks. Otolaryngol Head Neck Surg 128:32–38, 2003. Schlosser RJ, Wilensky EM, Grady MS, and Bolger WE. Elevated intracranial pressure in spontaneous cerebrospinal fluid leaks. Am J Rhinol 17:191–195, 2003.

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Kirtane MV, Gautham K, and Upadhyaya SR. Endoscopic CSF rhinorrhea closure: our experience in 267 cases. Otolaryngol Head Neck Surg 132:208–212, 2005. Lopatin AS, Kapitanov DN, and Potapov AA. Endonasal endoscopic repair of spontaneous cerebrospinal fluid leaks. Arch Otolaryngol Head Neck Surg 129:859–863, 2003. Woodworth BA. Spontaneous CSF leaks: a paradigm for definitive repair and management of intracranial hypertension. Otolaryngol Head Neck Surg 138:715–720, 2008. Holzmann D, and Wild C. Obesity as a risk factor for primary spontaneous rhinoliquorrhea. Arch Otolaryngol Head Neck Surg 129:324–326, 2003. Silver RI, Moonis G, Schlosser RJ, et al. Radiographic signs of elevated intracranial pressure in idiopathic cerebrospinal fluid leaks: a possible presentation of idiopathic intracranial hypertension. Am J Rhinol 21:257–261, 2007. Psaltis AJ, Overton LJ, Thomas WW 3rd, et al. Differences in skull base thickness in patients with spontaneous cerebrospinal fluid leaks. Am J Rhinol Allergy 28:73–79, 2014. Schick B, Brors D, and Prescher A. Sternberg’s canal–cause of congenital sphenoidal meningocele. Eur Arch Otorhinolaryngol 257:430– 432, 2000. Baranano CF, Cure J, Palmer JN, et al . Sternberg’s canal: fact or fiction. Am J Rhinol Allergy 23:167–171, 2009. e

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Spontaneous CSF rhinorrhea: prevalence of multiple simultaneous skull base defects.

Spontaneous cerebrospinal fluid (CSF) leaks are caused by intracranial hypertension. Given this underlying etiology, patients may be at risk for devel...
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