Spontaneous CSF Leaks From the Temporal Bone

Badr Eldin Mostafa, M.D.

Spontaneous

CSF

Leaks

From the Temporal Bone

Spontaneous cerebrospinal fluid (CSF) leaks from the temporal bone are a rare entity.1.2 The absence of a history of trauma, infection, or surgery makes the etiology obscure. Although congenital dehiscences of the tegmen occur in up to 6% of normal skulls, the incidence of spontaneous leaks from the temporal bone seems to be much less than spontaneous CSF leaks through the anterior posea. Spontaneous leaks may manifest themselves as recurrent attacks of meningitis, serous otitis media, hearing loss, external leaks, or pneumocephalus.3-6 The management of such cases is usually surgical, but it must be borne in mind that there may be multiple sites of leak.23 Fourteen cases of spontaneous leaks from the temporal bone are presented here.

PATIENTS AND METHODS This series includes 14 patients with different presentations who were eventually proven to have spontaneous CSF leaks from the temporal bone lateral to the labyrinth. All patients were males aged 45 to 72 (mean 54.2 years). No patient had a history of trauma, infection, or surgery of the head or temporal bone.

Clinical Presentations The different presentations are listed in Table 1. Hearing Loss

Hearing loss was the most frequent presentation (12 cases). In all cases the hearing loss was progressive and of relatively recent onset (1 week to 8 months, mean 3.3 months). All patients had a conductive component averaging 20 dB (10 to 35 dB). In seven a sensorineural component was present that could not be explained by any other cause. Fluid

A clear middle ear effusion was the next most common presentation. This was manifested as a fluid level behind an intact drum (five cases), as a clear fluid draining through a tympanostomy tube (two cases), as a watery component with mucopurulent discharge through a perforated drum (one case), or as a watery rhinorrhea (1 case). Mass

In two cases the most prominent presentation was a reddish fleshy pulsating mass. In one patient, the mass was present behind an intact drum; in the other, it pro-

Skull Base Surgery, Volume 7, Number 3, 1997, Department of Otorhinolaryngology, Head and Neck Surgery, Faculty of Medicine, Ain-Shams University, Cairo, Egypt. Reprint requests: Badr E. Mostafa, M.D., 8 El Magd Street, 11341-Cairo, Egypt. Copyright C 1997 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001. All rights reserved.

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SKULL BASE SURGERY/VOLUME 7, NUMBER 3 1997 Presentation Hearing loss

Table 1. Patient Presentations Number of Cases 12

Conductive Sensorineural Fluid Behind intact drum Through a tympanostomy tube Mucupurulent Rhinorrhea Mass Facial paresis

12 7 9 5 2 1

Investigations All patients underwent a computed tomography (CT) scan of the temporal bone with intravenous contrast (Fig. 1), eight underwent metrizamide cisternography, and six had a magnetic resonance imaging (MRI) examination (Fig. 2). In four cases, a lumbar puncture was performed and CSF pressure was measured.

1 2

1

truded through a defect in the tympanic membrane. Both cases were initially misdiagnosed elsewhere as glomus tumors. These masses were later proved to be granulation tissue covering the meningocele.

Facial Paresis Facial paresis was the presenting event in one patient who complained of 5 months of mixed watery and mucopurulent otorrhea and (?) granulations in the external meatus.

Surgery All patients underwent an extradural transmastoid repair under general anesthesia. A retroauricular incision was performed, as were a cortical mastoidectomy and an atticotomy. After proper exposure of the bony defect, the granulations were removed from the mastoid and from the surface of the dura. The ossicular chain was also carefully cleared of granulation tissue and its continuity preserved. The thinned-out bone around the site of the defect was excised back to healthy unyielding bone. The dura was reduced intracranially and a temporalis fascia graft tucked between the dura and bone. The graft was at least 30% larger than the size of the defect. With large defects (two cases) a rectus abdominis pascra was used. The defect was then supported with strips of conchal or costal cartilage placed between the bone and

Figure 1. Coronal CT scan showing the bone defect and soft tissue impinging on the ossicular chain. 140

SPONTANEOUS CSF LEAKS-MOSTAFA

Figure 2. Axial T2-weighted MRI showing the site ot leak.

fascia. The mastoid was packed with muscle only when the defect was large.

RESU LTS Preoperative Investigations The site of leak was determined preoperatively in 10 patients as a defect in the tegmen tympani shown in the coronal CT scan. In two cases, an additional defect could be found in the posterior fossa. CT cisternography was not highly accurate in determining the site of the defect. In three cases the site of leak could be detected, whereas in another three the dye was found in the mastoid but the exact site could not be detected. In two cases (2 of 8) the dye failed to reach the middle ear cleft. The site of the defect was clearly seen on the T2weighted MRI images in four of six cases. CSF pressure was normal in all four cases in which it was measured. In two patients, CSF pressure was measured postoperatively and was normal in both. Coronal CT scans were obtained in all patients one month after surgery. The site of repair was well delineated, with no active leaks, and the mastoid was well aerated. In no case was ventricular dilatation apparent

(Fig. 3).

Operative Findings In 12 cases, the defect was found in the tegmen at the level of the body of incus and extending to a variable distance posteriorly. In five cases the defect was limited to the region of the tegmen antri; in the other seven cases it extended back to the level of the solid angle. In the last two cases the defect was just anterior to the sino-dural angle. In two cases an additional defect was found in the posterior fossa dura. In one the area of weak bone involved the whole region of Trautmann's triangle with multiple areas of leak, and in the other case the defect was limited to the region just behind the solid angle. In all cases the meningeal hernia was covered with granulation tissue. In the 12 cases with defects involving the tegmen antri, the granulation tissue was found engulfing the body of incus and in six cases the same tissue extended along the long process of the incus to the level of the oval window niche.

Histopathologic Results The excised granulation tissue was examined after staining with hematoxylin and eosin. In all cases there was granulation tissue with areas of fibrosis, cellular infiltration by polymorphs, mast cells, and plasma cells. 141

SKULL BASE SURGERY/VOLUME 7, NUMBER 3 1997

Figure 3. Postoperative coronal CT scan showing the site of repair. The blood vessels were numerous and thin-walled (Fig. 4). In two cases the matrix was myxomatous, with thin elongated cells (Fig 5). No organisms were detected in pathologic specimens, and all aerobic and anaerobic cultures were negative.

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Clinical Results The leak was stopped in 12 cases in a single stage with a follow-up of 1.2 years (5 months to 2.4 years). The average duration of postoperative leak was 5.2 days (2 to 15 days).

Figure 4. Histopathologic specimen of excised granulation tissue. (Hematoxylin & eosin, mag. .< 1 50.)

Figure 4. Histopathologic specimen of excised granulation tissue. (Hematoxylin & eosin, mag.

x 150.)

SPONTANEOUS CSF LEAKS-MOSTAFA

Figure 5. Histopathologic specimen of excised granulation tissue showing myxomatous matrix. (Hematoxylin & eosin, mag. x 150.)

The extradural granulations may be arachnoid granulations,9 or some form of reaction to the leak, because the same tissue is present in the mastoid cells away from the dural hernia. Defects in the tegmen seem to be more frequent than posterior fossa defects,9'10 but in two of our cases both were present simultaneously; this did not change the clinical presentation or the surgical management. However, posterior defects tended to be larger and needed a costal cartilage and rectus fascia repair rather than temporalis fascia and conchal cartilage. A transmastoid extradural two-layered repair is easy and effective. Different techniques have been described.3,7"112 The technique used here emphasizes the following points: Care must be taken to "freshen" the DISCUSSION edges of the bony defect, as the bone in the immediate vicinity is usually thin and yielding and may not propSpontaneous CSF leaks from the temporal bone erly support the repair. This bone must be excised and away from the labyrinth may be more frequent than the repair done on healthy thick bone. All granulation thought. They may present in a variety of ways. A high tissue must be removed from the surface of the dura and index of suspicion should be maintained, especially in in the mastoid cavity, but there seems to be no need to older males with progressive conductive hearing loss excise the herniating dura, because it is almost always associated with a clear fluid in the middle ear. Similarly, healthy and unbreached. Packing of the mastoid cavity the presence of a fleshy pulsating mass in the middle ear is not needed in all cases and may be reserved for cases or external meatus without a history of bleeding may in- with large defects and poor bony support. dicate extradural granulations secondary to an acquired Although the exact cause of spontaneous CSF meningocele rather than a vascular tumor. The site of leaks is unknown, age-related atrophy of the dura and leak may not be accurately delineated with routine bone was incriminated in the etiology of CSF rhinorimaging using CT or even metrizamide CT cisternogra- rhea. Whether this is the cause in CSF otorrhea is not phy. MRI seems to be more accurate in this respect.7,8 clear. The absence of preformed foramina like the cribIn two cases a leak could be suspected after 1 month and the patient underwent another operation. In both the site of leak was found as part of the cartilage dropped in the mastoid. The fascia was replaced and a larger piece of cartilage placed. In both cases the leak stopped and the patients are free of recurrence 8 and 12 months later. Conductive heariXng loss was improved in seven patients and worse in two. No additional sensorineural loss was recorded. The patient presenting with facial palsy recovered after 2 months. There were no cases of meningitis or meningeal irritation and no deaths.

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SKULL BASE SURGERY/VOLUME 7, NUMBER 3 1997 riform plate and the firm attachments of the dura at the edges of the tegmen seem to give it more support. It is possible, however, that the constant CSF pressure waves can thin out the edges of congenital dehiscences in the tegmen in certain individuals, with gradual thinning and loss of support inviting herniation of the atrophic dura and cracks in its fibrillar structure that allow the leak to occur.2-5 It may be interesting to follow up these patients as well as those with repaired spontaneous CSF rhinorrhea because of the possibility of development of multiple cranial base leaks in the other location or in the occurrence of an empty sella syndrome.

3 4. 5.

6. 7. 8.

9.

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10. 11. 12.

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