BACKGROUND: Primary spinal melanoma is extremely rare, accounting for ∼1% of all primary melanomas. Typically presenting insidiously in the thoracic spinal cord, primary spinal melanomas can have an acute presentation due to their propensity to hemorrhage.
METHODS: Despite its rarity, primary spinal melanoma should be included in the differential diagnosis when a hemorrhagic pattern of T1 and T2 intensities is seen on magnetic resonance imaging. Furthermore, the complete diagnosis is crucial because the prognosis of a primary spinal melanoma is considerably more favorable than that of a primary cutaneous melanoma with metastatic spread.
CONCLUSIONS: Resection is the treatment of choice, with some authors advocating for postoperative chemotherapy, immunotherapy, and/or radiation. We describe a case of acute quadriplegia from hemorrhagic primary spinal melanoma requiring resection.

BACKGROUND: Primary intracranial rhabdomyosarcoma is an extraordinarily rare malignant tumor, with even fewer presenting with distant metastasis. To date, only five cases, including the one presented here, have been reported to present metastatic activity.
METHODS: A 12-year-old boy presented with a few days of headache, nausea, vomiting, but no neurological deficit. Brain computed tomography and magnetic resonance imaging demonstrated hydrocephalus and a cystic lesion with left parieto-occipital extension. After resection, pathology reported primary rhabdomyosarcoma, with positive desmin and myogenin on immunohistochemistry. The patient presented with pulmonary metastasis. The patient had an overall survival of 21 months after diagnosis with optimal treatment.
CONCLUSIONS: Rhabdomyosarcoma is a malignant neoplasm arising from undifferentiated skeletal muscle cells, with morphological, immunohistochemical, ultrastructural, or molecular genetic evidence of primary skeletal muscle differentiation. It presents with a rapidly worsening clinical course and the final outcome is poor. Treatment is widely based on protocols that have been proven to be effective in extracranial versions of these tumors, although repeatedly ineffective. Primary brain rhabdomyosarcoma poses a diagnostic challenge because of its infrequent presentation, grade of undifferentiation and tumor heterogeneity. Immunohistochemical and genetic testing have proven to be useful tools for diagnosis.

BACKGROUND: Multiple myeloma (MM) has the propensity to spread to vertebral bodies; however, extramedullary plasmacytomas involving the central nervous system are extremely rare.
METHODS: The authors report the first intradural extramedullary plasmacytoma in the lumbar region of the spine in a patient with preexisting MM. They present a 50-year-old female with severe back and radicular pain and progressive neurological deficit.
CONCLUSIONS: MM is typically treated with chemotherapy and radiation therapy. However, in this unique case, resection proved to be a key part of treatment.

BACKGROUND: Chordomas, which are rare malignant neoplasms arising from notochordal remnants, often cause gradually progressive clinical symptoms. Intradural cranial chordomas (ICCs) are extremely rare and generally have a favorable prognosis. However, the authors reported the case of a primary ICC originating in the pineal gland presenting with recurrent thalamic hemorrhage and displaying an aggressive postoperative clinical course.
METHODS: A 41-year-old man arrived at the emergency department with morning headaches and recurrent syncope that had lasted several months. Computed tomography and magnetic resonance imaging (MRI) revealed a pineal gland mass causing obstructive hydrocephalus and a subacute hematoma in the right thalamus. Three weeks after an endoscopic third ventriculostomy was performed, recurrent hemorrhage was observed in the right thalamus. The tumor was promptly removed surgically. The yellowish-white tumor did not exhibit abundant bleeding. No evidence of intratumoral hemorrhage around the hematoma pocket was found. Histopathological examination revealed the characteristics of a chordoma with minimal vascularity. MRI performed 10 weeks postoperatively for worsening headaches revealed abnormal enhancement of multiple cranial nerves, suggesting leptomeningeal seeding (LMS) of the tumor.
CONCLUSIONS: Despite radiotherapy and intrathecal chemotherapy, the patient\'s neurological status worsened; he died 2 years postoperatively. A pineal ICC may cause recurrent thalamic hemorrhage and potentially fatal LMS, even in the early postoperative period.

BACKGROUND: Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare sinonasal neuroectodermal malignancy with a slow onset of symptoms, favorable 5-year survival, and a propensity for delayed locoregional recurrence. Current treatment options include resection, adjuvant radiotherapy, and/or chemotherapy; however, because of its rarity and location, determining the optimal treatment for ENB has been challenging.
METHODS: ENBs strongly express somatostatin receptors (SSTRs), particularly SSTR2, providing a molecular target for imaging and therapy.
UNASSIGNED: The authors present a case series of ENBs imaged with [68Ga]-DOTATATE PET/MRI and PET/CT and discuss the emerging role of [68Ga]-DOTATATE PET for ENB diagnosis, staging, and treatment response monitoring.

BACKGROUND: Lower-grade insular gliomas often appear as expansile and infiltrative masses on magnetic resonance imaging (MRI). However, there are nonneoplastic lesions of the insula, such as demyelinating disease and vasculopathies, that can mimic insular gliomas.
METHODS: The authors report two patients who presented with headaches and were found to have mass lesions concerning for lower-grade insular glioma based on MRI obtained at initial presentation. However, on the immediate preoperative MRI obtained a few weeks later, both patients had spontaneous and complete resolution of the insular lesions.
CONCLUSIONS: Tumor mimics should always be in the differential diagnosis of brain masses, including those involving the insula. The immediate preoperative MRI (within 24-48 hours of surgery) must be compared carefully with the initial presentation MRI to assess interval change that suggests tumor mimics to avoid unnecessary surgical intervention.

UNASSIGNED: Leber\'s hereditary optic neuropathy (LHON) is a mitochondrial disease characterized by bilateral severe subacute central vision loss and a mutation in the mitochondrial DNA (mtDNA). The findings on cranial magnetic resonance imaging of patients with LHON vary from subtle to multiple white matter changes. However, they rarely present with diffuse infiltrative white matter changes.
METHODS: The authors reported a case with diffuse white matter changes mimicking gliomatosis cerebri (GC). The histological findings included only mild glial hyperplasia without immunohistochemical positivity, supporting the diagnosis of glial tumors. Analysis of mtDNA obtained from the blood and brain tissue revealed mutation of m.11778G>A in the NADH dehydrogenase 4 gene, which confirmed the case as LHON. Immunohistochemistry of the brain tissue revealed 8-hydroxy-2\'-deoxyguanosine positivity, suggesting the presence of oxidative stress.
CONCLUSIONS: LHON is extremely difficult to diagnose unless one suspects or knows the disease. The present case brings attention not only to LHON but also to other mtDNA-mutated diseases that need to be considered with diffuse white matter changes or GC.

Neuroimaging is an indispensable tool in the workup and management of patients with neurological disorders. Arterial spin labeling (ASL) is an imaging modality that permits the examination of blood flow and perfusion without the need for contrast injection. Noninvasive in nature, ASL provides a feasible alternative to existing vascular imaging techniques, including angiography and perfusion imaging. While promising, ASL has yet to be fully incorporated into the diagnosis and management of neurological disorders. This article presents a review of the most recent literature on ASL, with a special focus on its use in moyamoya disease, brain neoplasms, seizures, and migraines and a commentary on recent advances in ASL that make the imaging technique more attractive as a clinically useful tool.

OBJECTIVEFor stereotactic radiosurgery (SRS) planning, precise contouring of tumor boundaries and organs at risk is of utmost importance. Correct interpretation of standard neuroimaging (i.e., CT and MRI) can be challenging after previous surgeries or in cases of skull base lesions with complex shapes. The aim of this study was to evaluate the impact of 68Ga-DOTATOC PET/MRI on treatment planning for image-guided SRS by CyberKnife.METHODSThe authors retrospectively identified 11 meningioma treatments in 10 patients who received a 68Ga-DOTATOC PET/MRI prior to SRS. The planning target volume (PTV) used for the patients\' treatment was defined as the reference standard. This was contoured by a treating radiosurgeon (RS0) using fused planning CT and PET/MRI data sets. The same tumors were then contoured by another experienced radiosurgeon (RS1) and by a less-experienced radiosurgeon (RS2), both blinded to PET data sets. A comparison of target volumes with focus on volume-based metrics and distance to critical structures was performed. RS1 and RS2 also filled in a questionnaire analyzing the confidence level and the subjective need for the implementation of PET data sets for contouring.RESULTSAnalysis showed a subjective personal preference for PET/MRI in all cases for both radiosurgeons, particularly in proximity to critical structures. The analysis of the planning volumes per physician showed significantly smaller RS2-PTV in comparison to RS1-PTV and to RS0-PTV, whereas the median volumes were comparable between RS1-PTV and RS2-PTV (median: RS0: 4.3 cm3 [IQR 3.4-6.5 cm3] and RS1: 4.5 cm3 [IQR 2.7-6 cm3] vs RS2: 2.6 cm3 [IQR 2-5 cm3]; p = 0.003). This was also reflected in the best spatial congruency between the 2 experienced physicians (RS0 and RS1). The percentage of the left-out volume contoured by RS1 and RS2 compared to RS0 with PET/MRI demonstrated a relevant left-out-volume portion in both cases with greater extent for the less-experienced radiosurgeon (RS2) (RS1: 19.1% [IQR 8.5%-22%] vs RS2: 40.2% [IQR 34.2%-53%]). No significant differences were detected regarding investigated critical structures.CONCLUSIONSThis study demonstrated a relevant impact of PET/MRI on target volume delineation of meningiomas. The extent was highly dependent on the experience of the treating physician. This preliminary study supports the relevance of 68Ga-DOTATOC PET/MRI as a tool for radiosurgical treatment planning of meningiomas.

Some adult patients with moyamoya disease (MMD) undergoing revascularization surgery show an improvement or decline in cognition postoperatively. Revascularization surgery for ischemic MMD augments cerebral blood flow (CBF) and improves cerebral oxygen metabolism. However, cerebral hyperperfusion, which is a short-term, major increase in ipsilateral CBF that is much greater than the metabolic needs of the brain, sometimes occurs as a complication. Cerebral hyperperfusion produces widespread, minimal injury to the ipsilateral white matter and cortical regions. The aim of the present prospective study was to determine how changes in CBF due to arterial bypass surgery affect cognitive function in adult patients with symptomatic ischemic MMD and misery perfusion.
Thirty-two patients with cerebral misery perfusion, as determined on the basis of 15O gas positron emission tomography, underwent single superficial temporal artery-middle cerebral artery (M4 in the precentral region) anastomosis. Brain perfusion single-photon emission computed tomography (SPECT) studies were performed preoperatively, on the 1st postoperative day, and 2 months after surgery. Neuropsychological tests were also performed preoperatively and 2 months after surgery.
Postoperative neuropsychological assessments demonstrated cognitive improvement in 10 cases (31%), no change in 8 cases (25%), and decline in 14 cases (44%). Based on brain perfusion SPECT and symptoms, 10 patients were considered to have cerebral hyperperfusion syndrome, and all of these patients exhibited a postoperative decline in cognition. Relative precentral CBF on the 1st postoperative day was significantly greater in patients with postoperative cognitive decline (167.3% ± 15.3%) than in those with improved (105.3% ± 18.2%; p < 0.0001) or unchanged (131.4% ± 32.1%; p = 0.0029) cognition. The difference between relative precentral CBF 2 months after surgery and that before surgery was significantly greater in patients with postoperative cognitive improvement (17.2% ± 3.8%) than in those with no postoperative change (10.1% ± 2.4%; p = 0.0003) or with postoperative decline (11.5% ± 3.2%; p = 0.0009) in cognition.
Cerebral hyperperfusion in the acute stage after arterial bypass surgery impairs cognitive function. An increase in CBF in the chronic stage without acute-stage cerebral hyperperfusion improves cognitive function in adult patients with symptomatic ischemic MMD and misery perfusion.