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NEURORADIOLOGY Table of Contents   
Year : 2006  |  Volume : 16  |  Issue : 3  |  Page : 315-320
Role of MR cisternography in the diagnosis of cerebrospinal fluid rhinorrhoea with diagnostic nasal endoscopy and surgical correlation


Department of Radiology and Imaging Sciences and Department of Otolaryngology, Sri Ramachandra Medical College and Research Institute, Chennai - 600 116, India

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   Abstract 

Objectives : To study the usefulness and accuracy of MR cisternography as noninvasive study in the diagnosis of cerebrospinal fluid (CSF) fistula with diagnostic sinonasal endoscopy and surgical correlation. Material and Methods: Twenty four patients with clinically suspected CSF rhinorrhoea were examined for CSF fistula with MR cisternography. The MR imaging technique included 3mm thin T2 weighted coronal and sagittal sections using Fast spin echo. In addition 1.5mm thin T2 weighted coronal sections were also obtained using CISS (Constructive Interference in Steady State) sequence. MR findings were correlated with diagnostic sinonasal endoscopy and surgical findings. Results : MR cisternography demonstrated the presence of fistula in 17 patients, absence of fistula in seven patients. Out of 17 patients with fistula, the diagnosis could be confirmed in 14 patients by diagnostic sinonasal endoscopy/surgery. Out of the seven patients without fistula, there was positive correlation in six patients when they were followed up clinically and by diagnostic nasal endoscopy. However in one patient, fistula was demonstrated on CT cisternography and was confirmed on sinonasal endoscopic surgery. The accuracy, sensitivity of MR cisternography was 96, 94% respectively. Conclusion : MR cisternography is a useful and accurate noninvasive study in localizing the site and extent of CSF fistula.

Keywords: CSF fistula, CSF rhinorrhoea, MR cisternography

How to cite this article:
Rajeswaran R, Chandrasekharan A, Mohanty S, Murali K, Joseph S. Role of MR cisternography in the diagnosis of cerebrospinal fluid rhinorrhoea with diagnostic nasal endoscopy and surgical correlation. Indian J Radiol Imaging 2006;16:315-20

How to cite this URL:
Rajeswaran R, Chandrasekharan A, Mohanty S, Murali K, Joseph S. Role of MR cisternography in the diagnosis of cerebrospinal fluid rhinorrhoea with diagnostic nasal endoscopy and surgical correlation. Indian J Radiol Imaging [serial online] 2006 [cited 2019 Aug 18];16:315-20. Available from: http://www.ijri.org/text.asp?2006/16/3/315/29005

   Introduction Top


Cerebrospinal fluid (CSF) rhinorrhoea is a serious condition as there is leak of CSF through the base of skull. There is predisposition to develop meningitis. However the treatment has become easy after the advent of sinonasal endoscopes where surgery can be done in a minimally invasive way. Accurate localization of site and extent of CSF fistula is important to eliminate the chance of negative or recurrent exploration.

Several diagnostic studies have been used for the last two decades to detect CSF fistula. CT cisternography has been considered the most reliable and accurate method of diagnosing CSF fistula [1]. However this technique is invasive, time consuming and has a relative risk of infection. MR cisternography is a noninvasive technique, which does not involve the use of contrast material or spinal puncture. It can detect CSF fistula by inherent bright signal of CSF on T2 weighted images. The present study was done to evaluate the usefulness and accuracy of MR cisternography in the diagnosis of CSF fistula with diagnostic sinonasal endoscopy and surgical correlation.


   Material and Methods Top


Twenty four patients with clinical diagnosis of CSF leakage were subjected to MR cisternography. The study was conducted from October 2003 to September 2005. The patients ranged in age from 15 and 69years (mean 42) and included 11 males and 13 females. MRI study was done when the patient had active CSF leak.

MR cisternography was performed with 1.5 Tesla Siemens Magnetom Vision (Erlangen). The examination was done in supine position. T2 weighted axial sections of the brain were first obtained. This was done to rule out intracranial space occupying lesion. Coronal, sagittal thin T2 weighted fast spin echo images (FSE) were then obtained to cover anterior and middle cranial fossa. Parameters 6000-8000/100/2 (TR / TE / Excitation) 3mm sections 0 mm gap, 20cm FOV and 512 X 220 matrix were used. In addition T2 weighted coronal 1.5mm section using CISS were acquired with parameters 12.25 / 5.9 / 2 (TR / TE / Excitation), Flip angle 70, Slab thickness 80mm, 512 x192 matrix and 260mmFOV

MR criteria for locating CSF leakage included a CSF column communicating from the subarachnoid space extracranially and or herniation of brain tissue / meninges extracranially. The presence of a bone defect without concomitant communication of CSF / herniation of brain tissue/ meninges extracranially was not considered a site of CSF fistula.

The MR cisternographic findings were interpreted independently by two radiologists with more than six years MR experience. There was no significant discrepancy in their findings. Diagnostic sinonasal endoscopy was done in seven patients. Diagnostic endoscopy followed by surgical repair was done in 11 patients. Open craniotomy and surgery was done in three patients. Three patients were managed conservatively. The MRI findings were correlated with sinonasal endoscopy and surgical findings.


   Results Top


Out of the 24 patients 22 presented with CSF rhinorrhoea. Two patients presented with recurrent meningitis. Precipitating events for CSF leakage were related to trauma in six patients, iatrogenic in one patient, spontaneous in 16 patients [Table - 1]. The cause of CSF rhinorrhoea was attributed in one patient to posterior fossa arachnoid cyst causing compression on fourth ventricle and consequent dilated third, lateral ventricles. In another patient there was incidental arteriovenous malformation in left parieto-occipital region.

Of the 24 patients, seven revealed no evidence of CSF rhinorrhoea on MR cisternography. They were followed up clinically and with diagnostic endoscopy (with and without valsalva). Six patients responded to conservative management. One patient who continued to have CSF rhinorrhoea was evaluated with contrast CT cisternography in which CSF leak was picked up and was subsequently treated by endoscopic surgery.

MR cisternography depicted CSF rhinorrhoea in 17 patients accounting for 71 % of the group. CSF continuity extracranially was seen in17 sites in14 patients [Figure - 1]. Three patients each had two sites of CSF rhinorrhoea. Brain herniation was seen in three patients[Figure - 2]. The sites involved were - cribriform plate (11), Fovea ethmoidalis(2 ), cribriform plate and Fovea ethmoidalis(4) frontal sinus and Fovea ethmoidalis(1), sphenoid sinus (2) [Table - 2]. 11 of the 17 MR positive patients underwent surgical repair via endoscopic nasal surgery, three of them by open craniotomy and three were managed conservatively [Table - 3]. MR cisternographic findings correlated with surgical findings.


   Discussion Top


Over the years different techniques has yielded varying grades of success in the attempts to accurately locate the CSF fistula. Precise localization of CSF fistula helps in surgical planning and enhances the chance of successful dural repair. The risk of meningitis in untreated CSF fistula is 4% [2]. Plain CT studies alone have shown that detection of the fistula is low. However Prashant G et al revealed that high resolution CT identified a CSF fistula or its absence with accuracy, sensitivity, specificity in 92%, 92% and 100% [3]. It would be difficult to rely only on HRCT in the presence of multiple fractures or a hair line fracture of skull base because only fracture without dural tear will not cause CSF leakage [4]. CT is useful in showing bony defects but the important criteria of CSF continuity extracranially may be difficult to interpret because it may be difficult on CT to differentiate between CSF and mucosal pathology of paranasal sinus [3]. Sometimes anatomical bony defects in ethmoid without demonstrable CSF leak can occur in normal individuals.

CT cisternography has been considered to be the standard reference for diagnosis of CSF fistula. However CT cisternography is invasive, time consuming and carries slight risk of infection. It is relatively contraindicated in patients with active meningitis or raised intracranial pressure.

MR cisternography is a non-invasive technique that can detect CSF fistula in multiple planes without the disadvantage of lumbar puncture and ionizing radiation. On the T2 weighted fast spin echo, the inherent bright signal of CSF is well seen against the black background of bone and air in paranasal sinus [5],[6]. The leaked CSF has a characteristic signal that can generally distinguish from inflammatory paranasal secretions [3]. In their study, Prashant G et al had accuracy of 89% with MR cisternography using FSE (256x192 matrix) [3],[7]. In our study using FSE (512x220 matrix) and CISS techniques the accuracy, sensitivity and specificity are 96, 94 and 100%. With newer machines the pick up rate will increase because of the availability of high resolution protocols and upto 1 mm thickness can be obtained. As CSF rhinorrhoea can be intermittent, we did MRI only on those patients who had active CSF rhinorrhoea. This eliminated our false negatives.

The commonest site of CSF fistula in our study is cribriform plate[Figure - 3], which could be attributed to the thinnest bony structure of the skull base. The pathogenesis of the CSF leakage related to trauma was 25%. We attribute this decreased number as the surgeons in trauma settings preferred CT to see for fractures. There was associated posterior fossa arachnoid cyst in one patient [Figure - 4] and arteriovenous malformation in left parieto-occipital region in another All patients in the present study underwent imaging only on the basis of clinical suspicion of CSF leakage. It would have been useful to evaluate the nasal fluid for the presence of 2 transferrin in doubtful cases of CSF leakage. 2 transferrin is highly specific for human CSF and this test would have reduced the need to perform imaging in doubtful patients. This test was not used in our study due to non-availability. Sometimes the cribriform plate may be deep [Figure - 5]. This should not be misinterpreted as continuity of CSF extracranially [8]. Close observation will reveal that the cribriform plate is intact.

Seven patients had negative results on MR. They were treated conservatively. There was need to do contrast CT cisternography in only one patient who continued to have CSF rhinorrhoea where CSF leak was picked up.


   Conclusion Top


MR Cisternography using T2 weighted FSE and CISS techniques is noninvasive, accurate and highly useful in the diagnosis of CSF rhinorrhoea especially due to nontraumatic cause. We also recommend screening the brain by T2 weighted axial sections to rule out space occupying lesions.

 
   References Top

1.Drayer BP, Wilkins RH, Boehnke M, Horton JA, Rosenbaum AE. Cerebrospinal fluid rhinorrhoea demonstrated by metrizamide CT cisternogram. AJR 1977;129:149-51  Back to cited text no. 1  [PUBMED]  
2.Eljamel MS, Fay PM. Acute traumatic Cerebrospinal fluid rhinorrhoea: the risk of intracranial infection. British Journal of Neurosurgery1990;11:205-7  Back to cited text no. 2    
3.Shetty PG, Shroff MM, Sahani DV, Kirtane MV. Evaluation of high resolution CT and MR cisternography in the diagnosis of cerebrospinal fluid fistula. AJNR 1998; 19:633-9  Back to cited text no. 3  [PUBMED]  [FULLTEXT]
4.Stone JA, Castillo M, Neelon B, Mukherji SK. Evaluation of CSF leaks: High resolution CT compared with contrast enhanced CT and Radionuclide cisternography. AJNR 1999; 20:706-12  Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.El Gammal T, Sobol W, Wadlington VR, Sillers MJ, Crews C, Fisher WS 3rd, et al. Cerebrospinal fluid fistula: detection with MR cisternography. AJNR 1998;19:627-31  Back to cited text no. 5  [PUBMED]  [FULLTEXT]
6.Eljamel MS,Piddgeon CN, Toland J, et al. MRI cisternography and the localization of CSF fistula. British Journal of Neurosurgery1994;8:433-7  Back to cited text no. 6    
7.Lojana Tuntiyatorn, Jiraporn Laothammatas. Evaluation of MR cisternography in cerebrospinal fluid fistula. Journal Med Assc Thai 2004:87(12):1471-6  Back to cited text no. 7    
8.Heinz stammberger. Functional endoscopic sinus surgery- The Messerklinger technique. 1st Ed. NewYork: Mc Graw Hill,1991: 75-76  Back to cited text no. 8    

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Correspondence Address:
R Rajeswaran
Department of Radiology and Imaging Sciences, Sri Ramachandra Medical College and Research Institute, Chennai - 600 116
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-3026.29005

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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]

    Tables

[Table - 1], [Table - 2], [Table - 3]

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    Abstract
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    Material and Methods
    Results
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