Magnetic resonance imaging assessment of degenerative cervical myelopathy: a review of structural changes and measurement techniques.

Degenerative cervical myelopathy encompasses a spectrum of age-related structural changes of the cervical spine that result in static and dynamic injury to the spinal cord and collectively represent the most common cause of myelopathy in adults. Although cervical myelopathy is determined clinically, the diagnosis requires confirmation via imaging, and MRI is the preferred modality. Because of the heterogeneity of the condition and evolution of MRI technology, multiple techniques have been developed over the years in an attempt to quantify the degree of baseline severity and potential for neurological recovery. In this review, these techniques are categorized anatomically into those that focus on bone, ligaments, discs, and the spinal cord. In addition, measurements for the cervical spine canal size and sagittal alignment are also described briefly. These tools have resulted collectively in the identification of numerous useful parameters. However, the development of multiple techniques for assessing the same feature, such as cord compression, has also resulted in a number of challenges, including introducing ambiguity in terms of which methods to use and hindering effective comparisons of analysis in the literature. In addition, newer techniques that use advanced MRI are emerging and providing exciting new tools for assessing the spinal cord in patients with degenerative cervical myelopathy.

Primary germinoma of the medulla oblongata: illustrative case.

BACKGROUND: Primary central nervous system germinomas of the medulla oblongata are extremely rare and usually have been found in young female Asian patients. The authors present an illustrative case of a patient who presented with severe medullary and posterior cord syndrome, the first South American case published to date, to the authors' knowledge. OBSERVATIONS: Initially, the radiological differential diagnosis did not include this entity. The lesion was located at the obex and exhibited a well-delineated contrast enhancement without hydrocephalus. An emergency decompressive partial resection following functional limits was performed. After histological confirmation, radiotherapy was indicated, with complete remission achieved at a 6-month follow-up. The patient, however, continued to have a severe proprioceptive disorder. The literature review identified 21 other such patients. The mean age for this location was 23 years, with a strong female and Asian origin predilection. All tumors exhibited contrast enhancement, and only one presented with hydrocephalus. LESSONS: In the absence of elevated tumor markers, radiological clues such as a well-delineated, contrast-enhanced lesion arising from the obex, without hydrocephalus, associated with demographic features such as young age, female sex, and Asian heritage, should evoke a high level of suspicion for this diagnosis. Gross total resection must not be attempted, because this tumor is potentially curable with high-dose radiotherapy.

Primary microcystic/reticular schwannoma of the frontal bone: illustrative case.

BACKGROUND: To the best of the authors' knowledge, this is the first case of microcystic/reticular schwannoma arising in the frontal bone. OBSERVATIONS: An 18-year-old man presented to the authors' orthopedic clinic with a complaint of a progressively enlarging, painless mass in the frontal bone. It showed significant hyperintensity on T2-weighted imaging with progressive enhancement. Computed tomography combined with three-dimensional reconstruction showed expansive bone destruction with a soft tissue mass in the left side of the frontal bone, without calcification inside or a sclerotic margin around it. The mass was a microcystic/reticular schwannoma as confirmed by surgical pathology. LESSONS: The authors report a rare case of a microcystic/reticular schwannoma arising in the frontal bone, with relatively comprehensive imaging data that enabled them to learn more about this tumor.

Idiopathic dissecting cerebral aneurysm of the distal anterior cerebral artery in an infant successfully treated with aneurysmectomy: illustrative case.

BACKGROUND: Idiopathic dissecting cerebral aneurysms (IDCAs) are male dominant but are extremely rare in children. Many IDCAs in children are located in the posterior cerebral artery and the supraclinoid internal cervical artery. No cases of IDCA of the distal anterior cerebral artery (ACA) have been reported. OBSERVATIONS: A previously healthy 7-month-old boy experienced afebrile seizures and presented at the authors' hospital 1 week after the first seizure. He was not feeling well but had no neurological deficits. The authors diagnosed a ruptured aneurysm of the right distal ACA based on imaging results. He underwent emergency craniotomy to prevent re-rupture of the aneurysm. Using intraoperative indocyanine green videoangiography, the authors confirmed peripheral blood flow and then performed aneurysmectomy. Pathological examination of the aneurysm revealed a thickened intima, fragmentation of the internal elastic lamina, and a hematoma in the aneurysmal wall. The authors ultimately diagnosed IDCA because no cause was indicated, including a history of trauma. The boy recovered after surgery and was subsequently discharged with no complications. LESSONS: The authors reported, for the first time, IDCA of the distal ACA in an infant. The trapping technique is often used for giant fusiform aneurysms in infants. Indocyanine green videoangiography is useful for evaluating peripheral blood flow during trapping in this case.

Spinal intramedullary hemangioblastoma and schwannoma collision tumor: illustrative case.

BACKGROUND: Intramedullary spinal cord tumors represent a minority of intradural tumors. Among intramedullary spinal cord tumors, hemangioblastomas are uncommon, and schwannomas are extremely rare. Collision tumors are histologically distinct tumors that are intermingled and growing together. OBSERVATIONS: In this report, the authors describe a patient with a cervical intramedullary collision tumor involving a hemangioblastoma and schwannoma. To the authors' knowledge, no prior spinal intramedullary collision tumor involving multiple neoplasms has been described. The patient's presentation and management are described. LESSONS: Clinicians should consider the possibility of collision tumors when evaluating intramedullary spinal cord tumors, especially when patient presentation and radiographic findings are atypical. When tumors with similar radiographic characteristics form collision tumors, distinction using preoperative imaging can be extremely challenging. In addition, surgical management of intramedullary collision tumors, like that for all intramedullary spinal cord tumors, should involve meticulous perioperative care and a methodical surgical technique. Maximal safe resection will depend upon histopathological diagnosis, anatomical location of the tumor, presence of distinct dissection planes, and stability of neuromonitoring. Finally, ongoing research on the genetics of intramedullary spinal cord tumors may identify underlying genetic links for intramedullary hemangioblastomas and schwannomas.

Papillary glioneuronal tumor growing slowly for 26 years: illustrative case.

BACKGROUND: Papillary glioneuronal tumors (PGNTs) are classified as a type of World Health Organization grade I mixed neuronal-glial tumor. Most PGNTs involve cystic formations with mural nodules and solid components in the cerebral hemispheres, and PGNTs occur mainly in young adults. The long-term prognosis of PGNTs remains unclear. OBSERVATIONS: A 38-year-old male had been diagnosed with an arachnoid cyst associated with epilepsy in a local hospital. The initial magnetic resonance imaging (MRI) study showed the tumor as a heterogeneously enhanced nodule in the left postcentral gyrus. Subsequent MRI studies showed slow growth of the tumor for 26 years. He underwent gross total resection to control his epilepsy. The histopathological findings revealed pseudopapillary structures involving hyalinized blood vessels with a single or pseudostratified layer of cuboidal glial cells with round nuclei and scant cytoplasm. At the periphery of the lesion, Rosenthal fibers and acidophilic granule bodies were observed in the gliotic brain tissue. Immunohistochemically, some interpapillary cells were positive for NeuN. On the basis of these findings, the tumor was diagnosed as a PGNT. LESSONS: This PGNT showed slow growth for 26 years. When recognizing a slowly growing tumor in the cerebral hemispheres of relatively young people that is associated with epileptic seizures, PGNT should be considered as a differential diagnosis.

Primary intracranial aggressive fibromatosis arising in sella turcica: illustrative case.

BACKGROUND: Aggressive fibromatosis is a rare histologically benign but locally infiltrative myofibroblastic tumor. Primary intracranial aggressive fibromatosis (IAF) can exhibit a clinically malignant course. OBSERVATIONS: A 22-year-old otherwise healthy woman presented with left painful ophthalmoplegia. Magnetic resonance imaging (MRI) revealed a left sellar tumor with cavernous sinus invasion. Endoscopic transsphenoidal surgery was performed. The lesion could not be totally resected. An inflammatory myofibroblastic tumor was suspected, so steroid pulse therapy was introduced, but it was ineffective. The tumor recurred after a few months, and she complained of visual acuity loss, abducens nerve palsy, trigeminal neuralgia, and panhypopituitarism. The lesion was diagnosed as primary IAF by a pathological review. Gamma Knife radiosurgery was performed, and chemotherapies were introduced but ineffective. Her consciousness was disturbed, and MRI showed hypothalamic invasion of the tumor, occlusion and stenosis of carotid arteries, and cerebral stroke. Palliative care was introduced, and she died 32 months after the onset. The autopsy revealed tumor invasion to the cavernous sinus, optic nerve, hypothalamus, pituitary, and tonsillar herniation due to massive cerebral stroke. LESSONS: Radical resection can be impossible in patients with IAF. Radiotherapy and chemotherapy are not always effective for residual lesions. Adjuvant therapy for IAF remains to be explored.

Mixed germ cell tumor infiltrating the pineal gland without elevated tumor markers: illustrative case.

BACKGROUND: Tumors in the pineal region consist of various histological types, and correct diagnosis from biopsy specimens is sometimes difficult. The authors report the case of a patient with a mixed germ cell tumor infiltrating into the pineal gland despite showing no elevation of tumor markers. OBSERVATIONS: An 18-year-old man complained of headache and nausea and showed disturbance of consciousness. Magnetic resonance imaging showed hydrocephalus associated with a cystic pineal tumor. The patient underwent tumor biopsy followed by endoscopic third ventriculostomy for hydrocephalus in a local hospital. A pineocytoma was diagnosed, and the patient was referred to the authors' hospital for treatment. Concentrations of placental alkaline phosphatase, alpha-fetoprotein (AFP), and beta-human chorionic gonadotropin in cerebrospinal fluid were not elevated. However, the authors' review of the tumor specimen revealed some immature cells infiltrating the pineal gland. These cells were positive for AFP, Sal-like protein 4, and octamer-binding transcription factor 3/4; and the diagnosis was changed to mixed germ cell tumor. Chemoradiotherapy was initiated, followed by surgical removal of the residual tumor. LESSONS: Careful examination of all tumor specimens and immunohistochemical analyses are important for accurate diagnosis of pineal tumors.

Prediction of recurrence in solid nonfunctioning pituitary macroadenomas: additional benefits of diffusion-weighted MR imaging.

OBJECTIVE: A subset of benign, nonfunctioning pituitary macroadenomas (NFMAs) has been shown to undergo early progression/recurrence (P/R) during the first years after surgical resection. The aim of this study was to determine preoperative MR imaging features for the prediction of P/R in benign solid NFMAs, with emphasis on apparent diffusion coefficient (ADC) values. METHODS: We retrospectively investigated the preoperative MR imaging features for the prediction of P/R in benign solid NFMAs. Only the patients who had undergone preoperative MRI and postoperative MRI follow-ups for more than 1 year (at least every 6-12 months) were included. From November 2010 to December 2016, a total of 30 patients diagnosed with benign solid NFMAs were included (median follow-up time 45 months), and 19 (63.3%) patients had P/R (median time to P/R 24 months). RESULTS: Benign solid NFMAs with cavernous sinus invasion, failed chiasmatic decompression, large tumor height and tumor volume, high diffusion-weighted imaging (DWI) signal, and lower ADC values/ratios were significantly associated with P/R (p < 0.05). The cutoff points of ADC value and ADC ratio for prediction of P/R are 0.77 × 10-3 mm2/sec and 1.01, respectively, with area under the curve (AUC) values (0.9 and 0.91) (p < 0.01). In multivariate Cox proportional hazards analysis, low ADC value (< 0.77 × 10-3 mm2/sec) is a high-risk factor of P/R (p < 0.05) with a hazard ratio of 14.07. CONCLUSIONS: Benign solid NFMAs with low ADC values/ratios are at a significantly increased risk of P/R, and aggressive treatments accompanied by close follow-up with imaging studies should be considered.

Retrospective review of previous minor leak before major subarachnoid hemorrhage diagnosed by MRI as a predictor of occurrence of symptomatic delayed cerebral ischemia.

OBJECTIVE This study attempted to determine whether a previous minor leak correlated with the occurrence of symptomatic delayed cerebral ischemia (sDCI). METHODS The authors retrospectively evaluated sDCI-related clinical features and findings from MRI, including T1-weighted imaging (T1WI)-FLAIR mismatch at the time of admission, in 151 patients admitted with subarachnoid hemorrhage (SAH) within 48 hours of ictus. RESULTS The overall incidence of sDCI was 23% (35 of 151 patients). In all subjects, multivariate analysis revealed that World Federation of Neurosurgical Societies Grades II-V, age 70 years or older, presence of rebleeding after admission, a previous minor leak before the major SAH attack as diagnosed by T1WI-FLAIR mismatch, acute infarction on diffusion-weighted imaging, and CT SAH score were significantly associated with occurrence of sDCI. In patients with no previous minor leak before major SAH as diagnosed by T1WI-FLAIR mismatch, the incidence of sDCI was only 7% (7 of 97 patients). CONCLUSIONS A previous minor leak before major SAH as diagnosed by T1WI-FLAIR mismatch represents an important sDCI-related factor. When the analysis was restricted to patients with true acute SAH without a previous minor leak diagnosed by T1WI-FLAIR mismatch, the incidence of sDCI was extremely low.

Nonenhancing peritumoral hyperintense lesion on diffusion-weighted imaging in glioblastoma: a novel diagnostic and specific prognostic indicator.

OBJECTIVE Glioblastoma differentials include intracranial tumors, like malignant lymphomas and metastatic brain tumors with indiscernible radiological characteristics. The purpose of this study was to identify a distinct radiological feature for the preoperative differentiation of glioblastoma from its differentials, which include malignant lymphomas and metastatic brain tumors. METHODS Preoperative MR images, including diffusion-weighted imaging (DWI) studies (b = 1000 and 4000 sec/mm2), obtained in patients with newly diagnosed malignant tumor, were analyzed retrospectively after receiving approval from the institutional review board. Sixty-four patients with histologically confirmed glioblastoma, 32 patients with malignant lymphoma, and 46 patients with brain metastases were included. The presence of a nonenhancing peritumoral DWI high lesion (NePDHL, i.e., hyperintense lesion in a nonenhancing peritumoral area on DWI) was confirmed in both DWI sequences. Gray matter lesions were excluded. Lesions were termed "definite" if present within 3 cm of the hyperintense tumor border with a signal intensity ratio ≥ 30% when compared with the contralateral normal white matter in both sequences. Discriminant analysis between the histological diagnosis and the presence of Definite-NePDHL was performed, as well as Kaplan-Meier survival analysis incorporating the existence of Definite-NePDHL. RESULTS In 25% of glioblastoma patients, Definite-NePDHL was present, while it was conspicuously absent in patients with malignant lymphoma and metastatic brain tumors. The specificity and positive predictive value were 100%. In the glioblastoma subset, a higher preoperative Karnofsky Performance Scale score (p = 0.0028), high recursive partitioning analysis class (p = 0.0006), and total surgical removal (p = 0.0012) were associated with better median overall survival. Patients with Definite-NePDHL had significantly early local (p = 0.0467) and distant/dissemination recurrence (p < 0.0001) and poor prognosis (p = 0.0007). CONCLUSIONS The presence of Definite-NePDHL is very specific for glioblastoma and indicates poor prognosis. Definite-NePDHL is a significant indicator of early local and distant/dissemination recurrence in patients with glioblastoma. Studying peritumoral DWI and high-b-value DWI is useful for tumor differentiation.

An orphan disease: IgG4-related spinal pachymeningitis: report of 2 cases.

IgG4-related disease is relatively new disease entity and a rare one, and our knowledge of this entity continues to evolve. It was first described in the pancreas and since then has been described in virtually every organ. Spinal involvement resulting in pachymeningitis is rare, and there are only 8 reported cases of the same to date, with the cervicothoracic spine being the most commonly affected region. The authors describe 2 cases in which the patients presented with spinal compression resulting in myeloradiculopathy (Case 1) and radiculopathy (Case 2). Imaging of spine in both cases revealed an ill-defined contrast-enhancing lesion at the lumbar level. Preoperatively, a diagnosis of spinal tumor was made, but intraoperatively no spinal tumor was found. The diagnosis was established histopathologically. The disease has no particular defining features clinically or radiologically and can mimic common spinal tumors. It is important to accurately diagnose this rare entity because of its multisystem involvement and progressive course. Strict treatment guidelines have yet to be formulated. Although histologically this disease can mimic other inflammatory conditions, the presence of storiform fibrosis and an increased number of IgG4-positive plasma cells can help in clarifying the diagnosis.

Three-dimensional SPACE fluid-attenuated inversion recovery at 3 T to improve subthalamic nucleus lead placement for deep brain stimulation in Parkinson's disease: from preclinical to clinical studies.

OBJECTIVE Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established therapy for motor symptoms in patients with pharmacoresistant Parkinson's disease (PD). However, the procedure, which requires multimodal perioperative exploration such as imaging, electrophysiology, or clinical examination during macrostimulation to secure lead positioning, remains challenging because the STN cannot be reliably visualized using the gold standard, T2-weighted imaging (T2WI) at 1.5 T. Thus, there is a need to improve imaging tools to better visualize the STN, optimize DBS lead implantation, and enlarge DBS diffusion. METHODS Gradient-echo sequences such as those used in T2WI suffer from higher distortions at higher magnetic fields than spin-echo sequences. First, a spin-echo 3D SPACE (sampling perfection with application-optimized contrasts using different flip angle evolutions) FLAIR sequence at 3 T was designed, validated histologically in 2 nonhuman primates, and applied to 10 patients with PD; their data were clinically compared in a double-blind manner with those of a control group of 10 other patients with PD in whom STN targeting was performed using T2WI. RESULTS Overlap between the nonhuman primate STNs segmented on 3D-histological and on 3D-SPACE-FLAIR volumes was high for the 3 most anterior quarters (mean [± SD] Dice scores 0.73 ± 0.11, 0.74 ± 0.06, and 0.60 ± 0.09). STN limits determined by the 3D-SPACE-FLAIR sequence were more consistent with electrophysiological edges than those determined by T2WI (0.9 vs 1.4 mm, respectively). The imaging contrast of the STN on the 3D-SPACE-FLAIR sequence was 4 times higher (p < 0.05). Improvement in the Unified Parkinson's Disease Rating Scale Part III score (off medication, on stimulation) 12 months after the operation was higher for patients who underwent 3D-SPACE-FLAIR-guided implantation than for those in whom T2WI was used (62.2% vs 43.6%, respectively; p < 0.05). The total electrical energy delivered decreased by 36.3% with the 3D-SPACE-FLAIR sequence (p < 0.05). CONCLUSIONS 3D-SPACE-FLAIR sequences at 3 T improved STN lead placement under stereotactic conditions, improved the clinical outcome of patients with PD, and increased the benefit/risk ratio of STN-DBS surgery.

The predictive value of magnetic resonance imaging in evaluating intracranial arteriovenous malformation obliteration after stereotactic radiosurgery.

OBJECT: The current gold standard for diagnosing arteriovenous malformation (AVM) and assessing its obliteration after stereotactic radiosurgery (SRS) is digital subtraction angiography (DSA). Recently, MRI and MR angiography (MRA) have become increasingly popular imaging modalities for the follow-up of patients with an AVM because of their convenient setup and noninvasiveness. In this study, the authors assessed the sensitivity and specificity of MRI/MRA in evaluating AVM nidus obliteration as assessed by DSA. METHODS: The authors study a consecutive series of 136 patients who underwent SRS between January 2000 and December 2012 and who underwent regular clinical examinations, several MRI studies, and at least 1 post-SRS DSA follow- up evaluation at the University of Virginia. The average follow-up time was 47.3 months (range 10.1-165.2 months). Two blinded observers were enrolled to interpret the results of MRI/MRA compared with those of DSA. The sensitivity, specificity, positive predictive value, and negative predictive value for the obliteration of AVM were reported. RESULTS: On the basis of DSA, 73 patients (53.7%) achieved final angiographic obliteration in a median of 28.8 months. The sensitivity (the probability of finding obliteration on MRI/MRA among those for whom complete obliteration was shown on DSA) was 84.9% for one observer (Observer 1) and 76.7% for the other (Observer 2). The specificity was 88.9% and 95.2%, respectively. The false-negative interpretations were significantly related to the presence of draining veins, perinidal edema on T2-weighted images, and the interval between the MRI/MRA and DSA studies. CONCLUSIONS: MRI/MRA predicted AVM obliteration after SRS in most patients and can be used in their follow-up. However, because the specificity of MRI/MRA is not perfect, DSA should still be performed to confirm AVM nidus obliteration after SRS.

Clinical presentation and surgical outcomes of intramedullary neurenteric cysts.

OBJECT: Intramedullary neurenteric cysts (NECs) are exceedingly rare lesions and have been previously reported in case reports. The aim of this study was to determine the clinical manifestations, radiological features, and long-term prognosis of patients with such lesions. METHODS: The authors retrospectively reviewed the records of 13 patients with an intramedullary NEC. Each patient underwent MRI, laminotomy, and microsurgery. The accurate diagnosis was based on imaging and pathology findings. Each patient's follow-up status was determined through individual office visits and a structured telephone interview. RESULTS: The series included 7 male and 6 female patients. Progressive or intermittent motor deficit was the main symptom associated with or without pain or sensory disturbance. Five cysts were located in the cervical cord, 1 in the cervicothoracic cord, 3 in the thoracic cord, and 4 in the conus medullaris. Concurrent malformations included scoliosis (3 cases), fusion of rib (1 case), enlarged spinal canal (1 case), tethered spinal cord (1 case), and ectocardia (1 case). Gross-total resection of the cyst was achieved in 8 cases, and subtotal resection (STR) was achieved in 5 cases. All patients were followed up, with a mean duration of 66.5 months. Cyst recurrence was observed in 4 cases after STR. In 2 cases the patients underwent reoperation; the other 2 patients remained clinically stable and did not undergo reoperation. At the last evaluation, neurological function was improved in 11 patients and remained stable in 2 patients. CONCLUSIONS: Intramedullary NECs should be considered in the differential diagnosis of a middle-aged patient with intermittent neurological symptoms and concurrent malformations. Early surgery is advocated to prevent permanent neurological deficits. When gross-total resection cannot be achieved, maximally safe removal under the protection of intraoperative neuromonitoring is advised. Because of the high risk of cyst recurrence, routine follow-up MRI is needed. If a residual cyst shows obvious regrowth and results in neurological deficits, timely reoperation with a goal of STR should be performed.