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.