Skull base defects can manifest as meningocele/meningoencephalocele (M/ME) or cerebrospinal fluid (CSF) leaks. A pressure gradient across the defect often maintains symptoms, thereby necessitating medical intervention. The resulting CSF rhinorrhea is characterized by a clear, watery nasal discharge due to a breach in the CSF containment space [1,2]. A deficiency in all layers—including the arachnoid membrane, dura mater, bony skull base, periosteum, and nasal mucosa—at a specific site leads to skull base fistula formation [3].

Common leak sites include the roof of the anterior ethmoids, the lateral wall of the sphenoid sinus, and the posterior wall of the frontal sinus [4,5]. According to Har‐El [6], CSF leaks may be classified according to their site and cause. Given that the fovea ethmoidalis is the thinnest part of the skull base, it is the most common site of non‐traumatic, spontaneous CSF leaks.

Treatment options for defect closure range from conservative management to surgical repair, with the appropriate choice ultimately depending on the underlying cause and clinical presentation. Advances in endonasal approaches have significantly improved the outlook for ventral skull base defect repair. Successful endoscopic endonasal surgical repair of a CSF leak depends on precisely identifying the location and size of the fistula and understanding the detailed anatomy of the area. The goal of the endonasal endoscopic method is to address CSF leaks and achieve a durable dural repair using a minimally invasive technique, thereby avoiding the need for craniotomy [3]. Similarly, the use of a microscope is effective for repairing defects in the temporal bone region. Conventionally, a multilayered free tissue graft comprising fascia lata and fat is the preferred technique for reconstruction. For larger defects, pedicled nasoseptal and temporoparietal flaps are employed; however, each graft or flap harvest carries a risk of donor site morbidity. In the case of commonly used grafts such as fascia lata, complications such as hematoma formation and wound infection have been frequently reported. Harvesting a nasoseptal flap can result in a significant posterior septal defect. Moreover, not all small defects require the use of a large free graft or pedicled flap for secure closure.

For otorhinolaryngologists, the accessibility and maneuverability of temporalis fascia (TF) are well recognized. This study aims to share our experience in managing small (<1 cm) defects resulting in M/ME or CSF leaks. A combination of post‐aural TF and post‐aural soft tissue is used for defect closure, accompanied by supportive management.

Retrospective analysis of clinical records of patients who underwent repair for small (<1 cm) ventral and lateral skull base defects at a tertiary care teaching hospital from June 2022 to December 2023 was performed.

Data were extracted from clinical case records—including demographic characteristics, clinical and radiological features, operative findings, and follow-up visits—using a standardized data extraction proforma.

The use of TF is well known among otorhinolaryngologists. Its accessibility, maneuverability, and reliability have been well established in otolaryngology practice. However, TF is not routinely employed in the repair of skull base defects. Conventionally, grafts such as autologous cartilage, fascia lata, and abdominal fat (as free grafts) or pedicled flaps such as the nasoseptal flap are employed. The thickness and texture of fascia lata are considered appropriate for successful reconstruction. This retrospective study highlights the utility of using TF with soft tissue in a multilayered reconstruction, along with supportive management, as an effective solution.

The endonasal approach has emerged as a safe and effective modality for the treatment of skull base defects. The first step involves reducing the prolapsed meninges in cases of M/ME using energy devices (such as bipolar cautery or coblation) to fully expose the defect. Other measures, such as selecting an appropriately fitting graft and ensuring its stabilization, are also critical to successful repair [7].

CSF leaks can be classified as traumatic or non-traumatic. Traumatic leaks may be iatrogenic or accidental, often related to head injuries. Non-traumatic causes include spontaneous CSF leaks and leaks due to intracranial or skull base tumors that cause erosion of the skull base [8]. Spontaneous leaks can be classified as either high-pressure or normal-pressure. Obesity is a significant risk factor, as it increases intra-abdominal and intrathoracic pressures, potentially leading to chronic benign intracranial hypertension [9,10]. Traumatic leaks are more common and may occur due to iatrogenic factors (such as anterior skull base or endoscopic sinus surgery) or non-iatrogenic trauma to the skull base [11]. Accidental traumatic leaks managed conservatively tend to have a better prognosis compared to those of iatrogenic origin. All cases in this series were non-traumatic, spontaneous, normal-pressure leaks at presentation. Three cases were congenital defects, while three involved spontaneous leaks with very small bony defects in the ethmoids.

In pediatric patients, skull base defects often manifest as M/ ME. The loss of the barrier between the sterile intracranial compartment and the non-sterile sinonasal cavity increases the risk of serious complications, such as meningitis or brain abscesses [12]. Recurrent fever usually prompts further investigation, and in three cases, the skull base defect was incidentally discovered during a radiological workup for fever.

Before performing invasive imaging, such as CT cisternography, some experts recommend testing the fluid for beta-2 transferrin or, if possible, beta-trace protein to confirm or exclude CSF rhinorrhea according to the diagnostic algorithm [13]. Due to limited availability and cost concerns, routine beta-2 transferrin testing is not feasible in many settings. Only one patient in this series underwent this test; however, the absence of such testing in other cases did not affect management.

Imaging techniques are essential for diagnosing and pinpointing the site of the CSF leak. CT coronal scans of the paranasal sinuses at 1-mm intervals provide detailed anatomical information of the region. CT cisternography is particularly useful in cases of intermittent leakage and may be employed postoperatively to confirm the success of the reconstruction. Both contrast and non-contrast (3D T2 DRIVE sequence) MR cisternography are valuable noninvasive studies for evaluating brain parenchyma herniation through the defect [14-16]. The cribriform plate was the most frequently identified defect site, occurring in 80% of cases, consistent with previous studies.

Surgical treatment for CSF rhinorrhea can be performed either endonasally or transcranially. The transcranial approach is associated with higher morbidity due to craniotomy and has failure rates ranging from 20% to 40% [17]. In contrast, the endonasal endoscopic approach is less invasive and has reported success rates ranging from 90% to 94% [18].

The average bony defect size was 4 mm. Smaller defects were observed in spontaneous CSF leak cases, whereas congenital defects varied in size (up to 0.8×1.0 cm). The cases of prolapsed M/ME occupying the nasal cavity were larger than the bony defects. Endonasal endoscopic repair was accomplished in all cases, beginning with the reduction of the prolapsed M/ME using coblation and bipolar cautery down to the level of the bony defect. The surrounding mucosa was denuded, and sinus drainage was secured via antrostomy and appropriate widening of recesses. An effort was made to preserve the middle turbinate to facilitate graft stabilization. A TF graft in combination with fat/soft tissue was applied using an overlay technique to cover the defect. Multilayered free tissue grafts have higher success rates in defect closure [19].

The overall success rate in our case series was 83.33%. Four out of five cases with bony cribriform plate defects without dural involvement were successfully repaired without recurrence. One patient with a posterior fossa defect in the temporal bone was successfully repaired using a transmastoid approach.

The strength of TF is adequate for successful closure of the defect. There appear to be no contraindications for its use. However, larger defects may limit the applicability of this technique. In our experience, the TF graft that can be safely harvested without causing donor site complications is relatively small (approximately 2×2 cm). Hence, for larger bone defects or recurrent skull base defects, TF may not be the optimal choice for reconstruction. We acknowledge the small sample size as a limitation of the study. A prospective, comparative study with other free grafts, such as fascia lata, may provide further evidence for its efficacy. This series includes subcentimeter skull base defects, and only the necessary sinuses were opened while preparing the graft bed. We did not collect data regarding olfactory loss or nasal blockade. Meticulous handling of the nasal mucosa and the use of a precisely sized TF graft ensured early healing. Patients experienced nasal blockade only during the initial two days, which was attributed to the removable nasal packs. Future studies should consider evaluating these parameters when analyzing similar cases.

In conclusion, TF grafts combined with post-aural soft tissue may be effectively used for the repair of small (<1 cm) ventral and lateral skull base defects. Donor site morbidity associated with TF was minimal in all patients.