Hemorrhagic cervical juxta-facet cyst presenting with Brown-Séquard syndrome: illustrative case.

BACKGROUND: Intraspinal juxta-facet cysts of the spine are known to predominate at the lumbar level and is relatively rare at the cervical level. Most cervical spinal lesions are found incidentally, but they sometimes cause myelopathy or radiculopathy in a chronic course. OBSERVATIONS: The authors present a rare case of hemorrhagic cervical juxta-facet cyst presenting with Brown-Séquard syndrome. An 86-year-old woman presented with acute-onset right hemiparesis following neck pain and was admitted to the local hospital. She was started on antithrombotic therapy with a suspected diagnosis of cerebral infarction, but quadriplegia progressed 2 days later. Cervical magnetic resonance imaging revealed an intraspinal mass at the C4-5 level and she was referred to the authors' hospital. Her neurological findings on admission revealed right Brown-Séquard syndrome. In emergency surgery, the mass was resected with a posterior approach. Pathological findings showed hemosiderin deposition and fibroblast proliferation, consistent with a juxta-facet cyst with intracystic hemorrhage. The patient recovered well and returned to an independent daily life. LESSONS: Rarely, juxta-facet cyst of the cervical spine can cause acute Brown-Séquard syndrome due to intraspinal hemorrhage. In a case of hemiparesis that develops following neck pain, hemorrhagic cervical juxta-facet cyst should be taken into consideration as a differentiation.

Nonconvulsive status epilepticus due to pneumocephalus after suprasellar arachnoid cyst fenestration with transsphenoidal surgery: illustrative case.

BACKGROUND: Nonconvulsive status epilepticus (NCSE) requires prompt diagnosis and treatment, particularly after neurosurgical procedures for cerebral damage. Here, the authors reported an extremely rare case of suprasellar arachnoid cyst presenting with NCSE after cyst fenestration with transsphenoidal surgery, which was associated with pneumocephalus. OBSERVATIONS: A 61-year-old man presented with visual impairment and was diagnosed with a suprasellar arachnoid cyst on magnetic resonance imaging (MRI). The patient received cyst fenestration with endonasal transsphenoidal surgery. His visual symptoms improved immediately after the operation; however, on postoperative day 3, semicoma appeared and was prolonged. The patient was diagnosed with NCSE due to pneumocephalus based on MRI and electroencephalography (EEG) findings. The administration of antiepileptic drugs (AEDs) improved his clinical symptoms and the abnormal findings on MRI and EEG. LESSONS: This is the first case of NCSE with pneumocephalus after transsphenoidal surgery for a suprasellar arachnoid cyst. Pneumocephalus due to cerebrospinal fluid leakage can cause NCSE. Arterial spin labeling perfusion imaging and diffusion-weighted imaging are as useful for differentially diagnosing NCSE as EEG and AED tests.

Primary Spinal Intradural Extramedullary Mesenchymal Chondrosarcoma.

BACKGROUND: Among chondrosarcomas arising from bones and soft tissues, mesenchymal chondrosarcoma (MCS), especially primary spinal intradural extramedullary MCS, is extremely rare, and only 18 cases have been reported to date. We report an adult case of this rare condition mimicking meningioma. CASE DESCRIPTION: A 42-year-old woman presented with paraplegia and sensory disturbance associated with right-sided Brown-Séquard syndrome following back pain. Magnetic resonance imaging showed an intradural mass in the right dorsal spinal canal with homogeneous enhancement and dural tail sign at the T8 level. Computed tomography demonstrated a calcified portion in the mass. Following T7-8 laminectomies, an intradural extramedullary tumor was completely removed after detaching the tumor from the dura mater. The histopathologic diagnosis was MCS, and positron emission tomography showed no metastatic lesions at other sites. The patient did not receive adjuvant therapy, and magnetic resonance imaging revealed no evidence of recurrence during 2-year follow-up. CONCLUSIONS: Primary spinal intradural extramedullary MCS has been reported to have a better prognosis than MCS occurring in other regions. In a case with early complete surgical resection, adjuvant therapy should be considered at the time of recurrence.

Theoretical study of O2-H2O: potential energy surface, molecular vibrations, and equilibrium constant at atmospheric temperatures.

The intermolecular potential energy surface of O(2)-H(2)O was investigated at ab initio MP2 and MRSDCI levels using the aug-cc-pVTZ basis set. The vibrational levels were evaluated by numerically solving the Schrödinger equations for the nuclear motions with the ab initio potential functions using one- to three-dimensional finite-element methods. On the basis of the calculated partition functions, the equilibrium constant of the complex, K(p), was studied. The K(p) values at atmospheric temperatures of 200-300 K were found to be 1-2 orders of magnitude less than previous estimates from the harmonic oscillator approximation.