CASE REPORT Clival meningocele causing bilateral hearing loss in a child due to superficial siderosis of the central nervous system: case report Stephen J. Johans, MD,1 Kevin N. Swong, MD,1 Daniel J. Burkett, MD,2 Michael P. Wemhoff, MD,1 Sean M. Lew, MD,3 Chirag R. Patel, MD,4 and Anand V. Germanwala, MD1,4 Departments of 1Neurological Surgery and 4Otolaryngology, Loyola University Medical Center; 2Loyola University Chicago Stritch School of Medicine, Loyola University Medical Center, Maywood, Illinois; and 3Department of Neurological Surgery, Medical College of Wisconsin/Children’s Hospital of Wisconsin, Milwaukee, Wisconsin Superficial siderosis (SS) of the CNS is a rare and often unrecognized condition. Caused by hemosiderin deposition from chronic, repetitive hemorrhage in the subarachnoid space, it results in parenchymal damage in the subpial layers of the brain and spinal cord. T2-weighted MRI shows the characteristic hypointensity of hemosiderin deposition, classically occurring around the cerebellum, brainstem, and spinal cord. Patients present with progressive gait ataxia and sensorineural hearing impairment. Although there have been several studies, case reports, and review articles over the years, the clear pathophysiology of subarachnoid space hemorrhage remains to be elucidated. The proposed causes include prior intradural surgery, prior trauma, tumors, vascular abnormalities, nerve root avulsion, and dural abnormalities. Surgical repair of a dural defect associated with SS has been shown to be efficacious at preventing symptomatic progression. There have been several reports of dural defects within the spinal canal treated with surgery. Here, the authors present the first known case of a dural defect of the ventral skull base, namely a clival meningocele, presumed to be causing SS. In this case report, a 10-year-old girl with a history of head trauma at the age of 3 years was found to have a clival meningocele 3 years after her original trauma. On follow-up imaging, the patient was found to have radiographic growth of the meningocele along with evidence of SS of the CNS. The patient was treated conservatively until she began to have progressive hearing loss. It was presumed that the growing meningocele was the source of her SS. An endoscopic endonasal transclival approach with a multilayer dural reconstruction was performed to fix the dural defect and repair the meningocele in hopes of mitigating the progression of her symptoms. At her 12-month postoperative follow-up, she was doing well, with audiometry showing a slightly decreased hearing threshold in the left ear but improved speech discrimination bilaterally. Postoperative MRI showed a stable level of hemosiderin deposition and meningocele repair. Long-term follow-up will be necessary to evaluate for continued clinical stabilization or possible improvement. https://thejns.org/doi/abs/10.3171/2017.11.PEDS17302 S KEY WORDS clival meningocele; endoscopic skull base surgery; superficial siderosis; trauma; congenital uperficial siderosis (SS) of the CNS is an uncom- mon and often underdiagnosed disorder caused by chronic slow or repeated hemorrhage in the subarachnoid space.8 Hemosiderin deposition in the subpial layers of the brain and spinal cord results in parenchymal damage.18 The causes of hemorrhage include prior intradural surgery, prior trauma, tumors, vascular abnormalities, nerve root avulsion, and dural abnormalities.2,5,8,15,18,​ 24,29 Patients present with slowly progressive gait ataxia and sensorineural hearing impairment.11,18,27 Magnetic resonance imaging has made it easier to diagnosis SS of the CNS. T2-weighted MRI shows the characteristic hypointensity of hemosiderin deposition, classically occurring around the cerebellum, brainstem, and spinal cord.16,32 We present the case of a patient with SS that we hypothesized was caused by a skull base dural defect. The patient had a clival meningocele that was treated surgically via an endoscopic endonasal transclival approach. We also review previously reported cases of SS with dural defects in the spinal canal and the posterior fossa. Our case is the first known report of a patient with a dural defect of the ventral posterior fossa presumed to be causing SS of the CNS. ABBREVIATIONS SS = superficial siderosis. SUBMITTED May 31, 2017. ACCEPTED November 7, 2017. INCLUDE WHEN CITING Published online February 16, 2018; DOI: 10.3171/2017.11.PEDS17302. ©AANS 2018, except where prohibited by US copyright law J Neurosurg Pediatr February 16, 2018 1 S. J. Johans et al. Case Report History A 10-year-old girl was involved in a motor vehicle collision at the age of 3 years. At that time, a head CT scan revealed traumatic subarachnoid hemorrhage in the basal cisterns, including the prepontine cistern, and MRI revealed diffuse axonal injury. Her original CT and MRI studies of the brain showed no evidence of a clival fracture or a meningocele. Three years after the accident, she developed a sore throat and was noted to have left-sided tongue fasciculations. This prompted MRI of the brain that showed evidence of a clival meningocele. She was initially followed with observation and serial imaging. Three years after the clival meningocele was initially seen, a follow-up MRI study demonstrated SS of the posterior fossa. The patient had no subjective hearing loss at that time, but an audiogram was ordered on which mild left-sided highfrequency hearing loss was diagnosed. The patient completed an audiogram every 6 months for the next 2 years, and every audiogram showed evidence of progressively worsening hearing loss. Additionally, the family noticed progressive hearing loss and worsening balance problems including falls. Imaging demonstrated progression of the siderosis, with growth of the meningocele (Fig. 1), and she was referred to our clinic. Examination On our initial examination, the patient denied any head- ache, swallowing problems, or any signs or symptoms of a CSF leak. Besides her hearing loss, she continued to have left tongue fasciculations and left hemitongue atrophy. An audiogram was performed that showed evidence of worsened bilateral sensorineural hearing loss. Although the meningocele might have been completely unrelated to her symptoms, with evidence of CNS SS and progressive hearing loss, along with serial imaging showing radiographic progression of the meningocele, operative intervention for closure of the dural defect to possibly halt her clinical decline was extensively discussed with her and her family. With their consent she was taken to the operating room for an endoscopic endonasal repair of the clival meningocele. Operation An endoscopic endonasal transclival approach was performed with image guidance and neurophysiological monitoring. Some fibrinous material was identified within the bone during drilling of the clivus, consistent with possible prior fibrous union of a fracture. Once the superficial bone was removed, a dural defect and meningocele were identified and clear CSF was encountered. The arachnoid of the meningocele was noted to have a brownish discoloration, probably representing varying stages of hemorrhage and possibly the source of her siderosis. The bony defect was then widened and the meningocele was thoroughly fenestrated. The basilar artery and brainstem perforating vessels were identified. The meningocele was then re- FIG. 1. A and B: Preoperative axial and sagittal T2-weighted images showing the clival meningocele 3 years after trauma, with evidence of hemosiderin deposition within the cerebellar folia consistent with SS. C: Preoperative sagittal T2-weighted image showing progression of the clival meningocele. D: Postoperative sagittal T2-weighted image showing meningocele repair and multilayer dural closure with allograft and a vascularized nasoseptal flap (NSF). 2 J Neurosurg Pediatr February 16, 2018 S. J. Johans et al. paired with a multilayer dural reconstruction; this included placement of an allograft and vascularized pedicled nasoseptal flap (Fig. 2). Postoperative Course Postoperative brain MRI showed obliteration of the clival meningocele, with the dural defect reconstructed using a multilayer closure, including a nasoseptal flap (Fig. 1D). At her 8-month follow-up, her balance had subjectively improved, and she was able to return to taekwondo. She had no signs or symptoms of a CSF leak. A repeat audiogram obtained 8 months after surgery showed evidence of severe sensorineural hearing loss in both ears, with the left ear hearing slightly worse than the right ear. Hearing thresholds decreased for the right ear at 6000 Hz and 8000 Hz and for the left ear at 3000 Hz and above, which were both worse when compared with her last preoperative audiogram. Her subsequent audiogram performed 4 months later (1 year after surgery) suggests that in the right ear the hearing loss has stabilized. Her conventional audiometry showed no decreased thresholds in her right ear and a very slight decrease in the left ear. Interestingly, the word-discrimination scores improved minimally in the right ear (to 76%, from 68%) and significantly in the left ear (to 68%, from 40%). This most recent audiogram does provide some optimism that the progression of her hearing loss may have stabilized. Follow-up MRI sessions done 6 and 12 months postoperatively showed stable postsurgical changes related to the repair of the meningocele. A multilayer dural reconstruction was seen along the previous dural defect. Extensive susceptibility signals, findings compatible with SS, were again seen in the cerebellum and brainstem and were reportedly stable when compared with preoperative imaging. Discussion Superficial siderosis of the CNS is a rare and often unrecognized condition. The cardinal features of SS are deafness and cerebellar ataxia, which occur in approximately 90% of cases.8 Superficial siderosis is caused by chronic and repetitive hemorrhaging into the subarachnoid space. Parenchymal damage occurs from the deposition of hemosiderin around the brainstem, cerebellum, and spinal cord.17,18 The MRI studies reveal a rim of hypointensity on T2-weighted images, covering the surface of the brainstem, cerebellum, spinal cord, and sometimes cortical fissures. Even with MRI, the diagnosis may still be overlooked because the imaging abnormalities follow the contours of the brain.32 Gradient-echo T2-weighted images have even higher sensitivity for hemosiderin deposition, and can be used to aid in the diagnosis of SS.25 The ability of the brain to biosynthesize ferritin in response to prolonged contact with hemoglobin iron is important in the pathogenesis of SS. Ferritin synthesis is thought to be neuroprotective by binding iron released by FIG. 2. Endoscopic views through the right nasal cavity demonstrating the technique for the repair of a clival meningocele via a transsphenoidal approach. A: Intraoperative photograph demonstrating the relationship of the clival defect to the paraclival carotid artery and sella. B: The clivus has been drilled and the meningocele is visualized with entrance into the prepontine cistern. The basilar artery and hemosiderin deposition are identified. C: The first layer of our multilayer dural reconstruction, allograft, is placed within the posterior fossa defect. Figure is available in color online only. J Neurosurg Pediatr February 16, 2018 3 S. J. Johans et al. red blood cells.13 Tissue damage occurs in SS when this reserve is exhausted by chronic, repetitive hemorrhage.14 It is believed that the excess intrathecal iron may overload the ferritin biosynthesis capacity of the microglial cells; subsequent free radical damage and lipid peroxidation may cause neuronal injury. Accelerated ferritin synthesis in the Bergmann glia of the cerebellum may account for the preferential cerebellar involvement. The vulnerability of the eighth cranial nerve may be explained by its long glial segment, thus leading to greater length of hemosiderin deposition.13,17 There have been several studies, case reports, and review articles published over the years with the goal of providing insight into the underlying causes of subarachnoid bleeding in SS. Clear pathophysiology of this phenomenon is not known. In 1995, Fearnley et al. published a review of SS cases in the literature. An underlying cause was identified in 34 of 63 cases. A dural pathology was found in 47% of cases. This included CSF cavity lesions (meningoceles, pseudomeningoceles, pseudoencephaloceles) and cervical root pathology (root avulsions or epidural cysts).8 Brachial plexus injury with associated nerve root avulsion is a commonly reported association; brachial plexus injury may be associated with injury of nerve root sleeves, and this may lead to the formation of a pseudomeningocele.3,6 Tumors were seen in 35% of cases, and vascular abnormalities were seen in 18%. In 2006, Kumar et al. published a singleinstitution series of 30 patients with SS and found that the most common predisposing condition for patients with SS was prior trauma.18 The main finding from their paper was that a fluid-filled collection in the spinal canal was seen on MR images in 14 patients and on CT myelograms in 3 patients.20 These fluid collections presumably resulted from CSF leakage from dural defects in the spine.18 Of these 17 cases with a possible dural pathology, a history of trauma was present in 9, intradural surgery in 3, and a spontaneous dural tear in 1 patient. Three patients underwent surgical repair of their dural defect found in the thoracic spine (excluding cases with root avulsion), with a reduction in the fluid collection documented in 2 patients with postoperative MRI. Long-term clinical outcomes were not reported. Since Kumar et al. first described surgical repair of the defect, the efficacy of surgical intervention for the abnormal communication between the subarachnoid space and the epidural fluid collection has been reported.4,10,19,28 Egawa et al. published a review of SS cases associated with dural defects treated surgically with dural closure. They reviewed 13 total patients (11 previously reported and 2 cases of their own) with spinal dural defects that had been surgically repaired, excluding the cases with root avulsion. In all cases, preoperative MRI demonstrated fluid collection in the spinal canal.7 The CSF examinations showed typical findings for patients with SS (xanthochromia and increased red blood cell counts). The dural defects were generally closed using sutures or patches. When primary closure with sutures was not possible due to the location of the dural defect, fibrin glue, collagen sponge, muscle, or fat grafting was used to repair the defects.7,19 However, improvement on imaging and even CSF findings does not dramatically resolve the symptoms associated with SS. Egawa et al. concluded that the surgical re4 J Neurosurg Pediatr February 16, 2018 pair of dural defects has been shown to stop CSF leakage and subarachnoid hemorrhaging regardless of the closing method. In most cases, MRI indicated resolved or reduced fluid collection, and CSF analyses demonstrated postoperative resolution of the xanthochromia.7 However, only 2 of 9 patients showed partial improvement in gait, and 6 showed no change in neurological impairment. Based on these findings, Egawa et al. concluded that successful repair of a dural defect can stabilize the progression of neurological symptoms in most cases. They presented a patient with a 30-year history of symptoms who underwent closure of a dural defect but had progressive clinical deterioration. In patients with long histories of SS, symptoms may worsen even after a successful dural closure. Therefore, early diagnosis, detection of the dural defect, and an aggressive surgical closure may be important for at least stabilizing the neurological impairment in patients with SS of the CNS. The importance of dural closure is again demonstrated in a case report of a series of 3 patients who developed SS following posterior fossa operations in which dural closure was incomplete.22 In all 3 patients, revision surgery and complete duraplasty were performed to halt the progression of SS. The authors concluded that posterior fossa dural patency and pseudomeningocele development are risk factors for the latent development of SS. They recommended that revision duraplasty be performed in patients with posterior fossa pseudomeningoceles and SS to prevent progression of the disease. Clival meningoceles reported in the literature have been idiopathic or developed following a skull fracture.1,30,31 The previous patients who were reported either were asymptomatic or presented with CSF rhinorrhea.23 The CSF pressures and hydrostatic pulsatile forces may lead to the development of small holes in the middle fossa at the sites of arachnoid villi, with herniation of dura mater and arachnoid or brain tissue. When these defects are located over the underlying lateral extension of the sphenoid sinus, an encephalocele or meningocele can develop in the clivus and lead to CSF leakage through the sinuses.1 Our patient had suffered a previous trauma when younger, which may have caused a dural injury or even an occult clival fracture. Although there was no evidence of a clival fracture on the original scans at the time of the trauma, intraoperative findings suggested a previous fracture with fibrous bone and bony spicules. The probable previous dural injury or clival fracture may have allowed for a meningocele to form through constant pulsations and expansion of the previous injury. Extradural fluid collections, when in continuity with the intradural space, allow for decreased CSF pressure due to an increase in volume. The dural defect, along with pulsations from the meningocele, may have led to stress within the walls of the friable dural defect and arachnoid. The vessels within this dura and arachnoid may have been engorged from CSF hypovolemia due to the meningocele growing outside of the intradural space. This combination of friability, continued stress, and engorgement may have led to small vessels rupturing within the subarachnoid space. The dura and arachnoid with friable vessels will tear and retear over many years.21 S. J. Johans et al. Our patient is the first one to our knowledge to have a clival meningocele presumed to be causing SS of the CNS. The endoscopic endonasal approach to the sphenoid sinus has been proven to be effective for CSF rhinorrhea associated with trauma, prior transsphenoidal or anterior cranial base surgery, and even medial intrasphenoidal and sellar encephaloceles. We performed an endoscopic endonasal approach to the sphenoid sinus and clivus.9,12 The bone defect and meningocele in the clivus were seen and repaired with a multilayer closure, including a vascularized nasoseptal flap.26 Postoperative imaging showed good positioning of the allograft and nasoseptal flap. The patient will be followed with serial MRI, audiometry, and clinical examinations. Although the postoperative hearing decline noted on her audiogram 8 months after her procedure is disappointing, and despite the fact that her hearing loss may be unrelated to the pathophysiology of the meningocele and may continue to worsen, there are reasons to remain optimistic. Several studies discussed in this report have shown that successful repair of a dural defect can potentially stabilize the long-term progression of neurological symptoms. Our patient’s hearing decline seen on her first postoperative audiogram (8 months after surgery) may have happened preoperatively—there was a 3-month interval between her last preoperative audiogram and surgery. Her subsequent audiogram performed 4 months later (1 year after surgery) suggests that the right ear hearing loss has stabilized at this point with no changes in thresholds. Even though conventional audiometry showed a very slight decrease in thresholds in the left ear, there were still positive findings, with word-discrimination scores significantly improving in the left ear and showing slight improvement in the right ear. Additionally, 1 year may not be enough time to allow for her hearing loss to completely stabilize, and repeat audiograms in the future may show that her hearing loss has not worsened. The overall extent of the SS remains stable and will be followed with future imaging. Conclusions The progression of neurological deficits in SS associated with dural defects may be slowed or stabilized with surgical closure. There are several reports of spinal canal defects resulting in CNS SS in which surgical repair has led to radiographic improvement and clinical stability. 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