Two cases of spontaneous temporal encephalocele

A Comparison of Outcomes Using Combined Intra- and Extradural versus Extradural-Only Repair of Tegmen Defects

Objective  Tegmen tympani or tegmen mastoideum defects involve dehiscence of the temporal bone that can be a source of cerebrospinal fluid (CSF) otorrhea. Herein, we compare a combined intra-/extradural repair strategy with an extradural-only repair as it pertains to surgical and clinical outcomes. Design  A retrospective review from our institution was performed of patients with tegmen defects requiring surgical intervention. Participants  Patients with tegmen defects who underwent surgery (combined transmastoid and middle fossa craniotomy) for repair of tegmen defects between 2010 and 2020 were inclined in this study. Results  A total of 60 patients with 40 intra-/extradural (mean follow-up time: 1,060 ± 1,103 days) and 20 extradural-only (mean follow-up time: 519 ± 369 days) repairs were identified. No major differences in demographic factors or presenting symptoms were identified between the two cohorts. There was no difference in hospital length of stay between the two patient cohorts (mean: 4.15 vs. 4.35 days, p  = 0.8). In the extradural-only repair technique, synthetic bone cement was more frequently used (100 vs. 7.5%, p  < 0.01), whereas in the combined intra-/extradural repair, synthetic dural substitute was used more often (80 vs. 35%, p  < 0.01), with similar successful surgical outcomes achieved. Despite disparities in the techniques and materials used for repair, there were no differences in complication rates (wound infection, seizures, and ossicular fixation), 30-day readmission rates, or persistent CSF leak between the two treatment cohorts. Conclusion  The results of this study suggest no difference in clinical outcomes between combined intra-/extradural versus extradural-only repair of tegmen defects. A simplified extradural-only repair strategy can be effective, and may reduce the morbidity of intradural reconstruction (seizures, stroke, and intraparenchymal hemorrhage).

Encephalocele-Associated Drug-Resistant Epilepsy of Adult Onset: Diagnosis, Management, and Outcomes

Epileptogenic encephaloceles, most frequently located in the temporal lobe, are a known lesional cause of focal epilepsy. Data are limited regarding diagnosis, management, and outcomes of patients with epilepsy in the setting of an encephalocele, because the literature mostly comprises case reports, case series, and retrospective studies. We conducted a broad literature review for articles related to encephaloceles and epilepsy regardless of level of evidence. Hence, this review provides a summary of all available literature related to the topic. Thirty-six scientific reports that fulfilled our inclusion criteria were reviewed. Most reported patients presented with focal impaired awareness seizures and/or generalized tonic-clonic seizures. Although most of the encephaloceles were located in the temporal lobe, we found 5 cases of extratemporal encephaloceles causing epilepsy. More patients who underwent either lesionectomy or lobectomy were seizure free at time of follow-up. In the temporal lobe, there is no clear consensus on the appropriate management for epileptic encephaloceles and further studies are warranted to understand the associated factors and long-term outcomes associated with epilepsy secondary to encephaloceles. Reported data suggest that these patients could be manageable with surgical procedures including lesionectomy or lobectomy. In addition, because of data suggesting similar results between procedures, a more conservative surgery with lesionectomy and defect repair rather than a lobectomy may have lower surgical risks and similar seizure freedom.

A Case of An Unusual Bell's Palsy Mimic

We discuss the case of a 5-year-old boy who presented with an isolated left-sided cranial nerve 7 palsy that was initially magnetic resonance imaging negative. Owing to continued symptoms, repeat magnetic resonance imaging was performed and showed a temporal bone encephalocele. A review of the differential diagnosis of cranial nerve 7 palsy, warning signs signaling the need for additional workup, and a discussion of temporal lobe encephaloceles is provided in this case report. It is important to recognize that structural lesions can closely mimic idiopathic Bell's palsy, despite initial negative imaging.

Detection and Characteristics of Temporal Encephaloceles in Patients with Refractory Epilepsy

BACKGROUND AND PURPOSE

Temporal encephaloceles are increasingly visualized during neuroimaging assessment of individuals with refractory temporal lobe epilepsy, and their identification could indicate an intracranial abnormality that may be related to a potential seizure focus. Careful review by an experienced neuroradiologist may yield improved detection of TEs, and other clinical, neurophysiologic, and radiologic findings may predict their presence.

MATERIALS AND METHODS

Data were reviewed retrospectively in patients at our institution who were presented at a multidisciplinary conference for refractory epilepsy between January 1, 2010, and December 31, 2016. Clinical, neurophysiologic, and imaging data were collected. An expert neuroradiologist reviewed the latest MR imaging of the brain in patients for whom one was available, noting the presence or absence of temporal encephaloceles as well as other associated imaging characteristics.

RESULTS

A total of 434 patients were reviewed, 16 of whom were excluded due to unavailable or poor-quality MR imaging. Seven patients had temporal encephaloceles reported on initial imaging, while 52 patients had temporal encephaloceles identified on expert review. MR imaging findings were more often initially normal in patients with temporal encephaloceles (P < .001), and detection of temporal encephaloceles was increased in patients in whom 3T MR imaging was performed (P < .001), the T2 sampling perfection with application-optimized contrasts by using different flip angle evolutions sequence was used (P < .001), or the presence of radiologic findings suggestive of idiopathic intracranial hypertension was noted. Seizure onset by scalp electroencephalogram among patients with temporal encephaloceles was significantly more likely to be temporal compared with patients without temporal encephaloceles (P < .001). A significant correlation between intracranial electroencephalogram seizure onset and patients with temporal encephaloceles compared with patients without temporal encephaloceles was not observed, though there was a trend toward temporal-onset seizures in patients with temporal encephaloceles (P = .06).

CONCLUSIONS

Careful review of MR imaging in patients with refractory temporal lobe epilepsy by a board-certified neuroradiologist with special attention paid to a high-resolution T2 sequence can increase the detection of subtle temporal encephaloceles, and certain clinical and neurophysiologic findings should raise the suspicion for their presence.

Intradiploic encephalocele of the primary motor cortex in an adult patient: electrophysiological implications during surgery

Encephaloceles are herniations of brain parenchyma through congenital or acquired osseous-dural defects of the skull base or cranial vault. Different types of symptoms, due to CSF fistulas, meningitis, or seizures, are often associated with this condition. The authors present a rare case of spontaneous right frontal parasagittal encephalocele in a 70-year-old man who was experiencing a spastic progressive paresis of his left lower limb. Results of routine electrophysiological workup (motor evoked potentials, somatosensory evoked potentials, and electroneuromyography), as well as those of MRI of the spinal cord, were normal. A brain MRI study detected a partial herniation of the right precentral gyrus through a meningeal defect into the diploe, embedding corticospinal fibers. The patient underwent navigated craniotomy. Intraoperative neuromonitoring of motor function with transcranial electrical stimulation and direct cortical stimulation indicated the presence of motor cortex inside the encephalocele. Thus, the brain parenchyma was carefully released without resection to preserve motor function and, finally, a cranioplasty was performed. After a few months, the patient demonstrated considerable improvement in his left lower-limb function and, after 1 year, he had fully recovered. Intraoperative electrophysiological monitoring and mapping allowed for the determination of the best surgical strategy for the isolation of the encephalocele and correlated well with preoperative multimodal MRI.

Occult temporal lobe encephalocoele into the transverse sinus

In this article we present a case of an incidental encephalocoele protruding through a dural defect into the transverse sinus. Encephalocoeles are usually described as a herniation of the meninges and brain parenchyma through a bony defect of the cranium or base of skull. To our knowledge, there are only a few patients reported in the literature of occult encephalocoeles through dural defects. Our case study highlights that encephalocoele should be a differential diagnosis for a filling defect in this location.

Excavating Meckel's cave: Cavum-trigeminale-cephaloceles (CTCs)

BACKGROUND AND PURPOSE

Cavum-trigeminale-cephaloceles (CTCs) are rare lesions of Meckel's cave and the petrous apex. Despite distinctive imaging features, they are frequently mistaken for other petrous apex lesions. In contrast to many of these entities, CTCs do--when asymptomatic--not require any invasive work-up or even surgical excision. Since correct diagnosis has profound impact on clinical decision-making, we report on a series of CTCs with distinct imaging features and their important differential diagnoses.

MATERIAL AND METHODS

We report a retrospective series of 5 patients with CTCs and the associated imaging features including the absence of diffusion restriction and solid contrast enhancement as well as their size, anatomical location with regard to adjacent structures and the remodeling or erosion of surrounding bony structures.

RESULTS

Our series contains the largest CTC that has, to the best of our knowledge, been reported so far. It revealed a deep cervical extension and was initially mistaken for a branchial cleft cyst. Furthermore, we show that CTCs can erode or remodel important structures such as canalis nervi hypoglossi, canalis Vidiani, foramen rotundum, ovale, lacerum and spinosum without causing clinical symptoms.

CONCLUSION

In contrast to previous reports in which asymptomatic CTC did not include critical structures such as the foramina rotundum, ovale, lacerum or spinosum or the hypoglossal or Vidian canal, we show that CTCs can be asymptomatic even when eroding or remodeling such clinically important structures. When extending below the skull base, CTCs are a rare differential diagnosis to cystic cervical lesions such as type II branchial cleft cysts.