Linda J. Bagley

Magnetization transfer imaging of traumatic brain injury

Magnetization transfer imaging (MTI) has been shown to be sensitive for the detection of white matter abnormalities in entities such as multiple sclerosis, progressive multifocal leukencephalopathy, and wallerian degeneration. Our hypothesis was that MTI would detect traumatic white matter abnormalities (TWMA) and provide information additional to that obtainable with routine spin‐ and gradient‐echo imaging. We hypothesized that the presence of TWMA defined by MTI would correlate with outcome following TBI. Twenty‐eight victims of head trauma and 15 normal controls underwent magnetic resonance imaging including MTI. Magnetization transfer ratios (MTR) were calculated for areas of shearing injury and for normal‐appearing white matter (NAWM) in locations frequently subject to diffuse axonal injury. Abnormal MTRs were detected in NAWM in eight patients. All eight had persistent neurologic deficits, including cognitive deficits, aphasia, and extremity weakness. Seven of the 28 patients had no abnormal findings on neurologic exam at discharge, transfer, or follow‐up. None of these patients had an abnormal MTR in NAWM. In the remaining 13 patients, who had persistent neurologic deficits, no regions of abnormal MTR were detected in NAWM. MTI is a sensitive method for the detection of TWMA. Detection of abnormal MTR in NAWM that is prone to axonal injury may predict a poor patient outcome. The presence of normal MTR in NAWM in these areas does not necessarily confer a good outcome, however. J. Magn. Reson. Imaging 2000;11:1–8.

Endovascular stent treatment of cervical internal carotid artery aneurysms with parent vessel preservation

BACKGROUND Aneurysms involving the cervical portion of the internal carotid artery (ICA) frequently result from prior trauma or dissection. CASE DESCRIPTIONS Two patients are reported with cervical internal carotid artery aneurysms. In both cases, disease involving the contralateral ICA precluded safe treatment of the aneurysms by ICA occlusion. Endovascular stents placed across the diseased portion of the artery resulted in thrombosis of the aneurysm with preservation of the parent artery. CONCLUSION Endovascular stent placement should be considered for treatment of aneurysms involving the cervical ICA when preservation of the parent vessel is necessary.

Alternative management considerations for ethmoidal dural arteriovenous fistulas

BACKGROUND Ethmoidal dural arteriovenous fistulas (EDAFs) are an unusual type of intracranial vascular lesion that commonly present with acute hemorrhage. They are often best treated surgically; however, recent endovascular advances raise questions concerning the best therapeutic approach. METHODS We present 7 cases of EDAFs managed at this institution over a 6-year period, which demonstrate the broad spectrum of clinical behavior associated with the lesions. Four patients presented with intracranial hemorrhage, 1 patient with rapidly progressive dementia, 1 patient with a proptotic, red eye, and 1 with a retro-orbital headache. RESULTS One patient underwent no treatment, 1 underwent embolization alone, 2 underwent embolization and resection, and 3 patients underwent resection alone. There was complete obliteration of the EDAF in all of the patients who underwent surgical resection. Embolization was performed through the external carotid circulation and not the ophthalmic artery. There were no treatment-related neurologic deficits. CONCLUSIONS Treatment is best managed with a multidisciplinary approach, which emphasizes complete resection of the lesions with assistance from interventional neuroradiology techniques. However, each patient must be evaluated independently as treatment may vary depending on the angioarchitecture of the lesion.

Localization of traumatic oculomotor nerve palsy to the midbrain exit site by magnetic resonance imaging

PURPOSE To present the magnetic resonance imaging findings for a patient with traumatic oculomotor nerve injury. METHODS We examined a patient with a right pupil-involving oculomotor nerve palsy after severe closed head trauma. RESULTS Magnetic resonance imaging of the brain demonstrated marked signal hypointensity on gradient-echo T2*-weighted images consistent with hemorrhage at the midbrain exit site of the right oculomotor nerve. CONCLUSIONS Distal fascicular damage or partial rootlet avulsion is a mechanism of injury in some traumatic oculomotor nerve palsies. Gradient-echo T2*-weighted magnetic resonance imaging is the most sensitive method to detect hemorrhagic changes associated with shearing injury.

Spinal cord arteriovenous fistulas involving the conus medullaris: presentation, management, and embryologic considerations

BACKGROUND Spinal cord arteriovenous fistulas (SCAVF) are uncommon congenital lesions that usually involve the most caudal aspects of the cord. We present three cases of SCAVF that illustrate the clinical manifestations and possible management options. The characteristic involvement of the conus medullaris and an associated tethered spinal cord in one of our patient suggests that a disorder of secondary neurulation may be involved in the formation of these arteriovenous shunt lesions. METHODS Review of records and radiologic studies in three consecutive patients with SCAVFs treated at this institution. RESULTS All three patients had SCAVF involving the lower lumbar spinal cord segments or the conus. One of the conus lesions was associated with tethering of the spinal cord. One small lesion (Type A) was treated surgically, whereas the two larger lesions (Type B) were treated using interventional neuroradiologic techniques. CONCLUSIONS Both surgical and endovascular method have a role in management of these unusual spinal cord vascular malformations. The association with tethered cord suggests that the propensity for SCAVM to occur in the most caudal portions of the spinal cord may result from failure of secondary neurulation to properly develop the unique and complex vascular anatomy of the region.

Unusual behavior of clear cell chondrosarcoma

We report two unusual cases of clear cell chondrosarcoma. Both emphasize the slow-growing nature of the lesion and the need for long-term follow-up. Additionally, the clinical, radiologic and histologic characteristics of this neoplasm are discussed.

Anterior choroidal artery supply to the posterior cerebral artery distribution: embryological basis and clinical implications

OBJECTIVE AND IMPORTANCE: We report four cases of anomalous anterior choroidal artery supply to the temporal, parietal, and occipital cortical regions normally supplied by branches of the posterior cerebral artery. Three of these cases were associated with significant intracranial vascular pathology. We examine the embryological basis for the anomalous vascular anatomy to emphasize the potential variability of the anterior choroidal artery distribution and illustrate the spectrum of this variability angiographically. These variants may also have significant implications for surgical and endovascular treatment. CLINICAL PRESENTATION: One patient was diagnosed with an arteriovenous malformation, and two patients were diagnosed with aneurysms, one of which presented with a subarachnoid hemorrhage. INTERVENTION: The patient with the arteriovenous malformation underwent preoperative embolization and surgical resection, one patient with an aneurysm was treated via surgical clipping, and the other aneurysm underwent endovascular coiling. CONCLUSION: This group of patients illustrates an underemphasized but potentially important vascular anomaly. Phylogeny and embryology of the intracerebral vessels suggest a mechanism related to transposed distributions. Careful attention must be directed to the microvascular anatomy of the intracerebral circulation so that these anomalies are recognized and, if necessary, factored into surgical and interventional planning.

Case report 822

Fig. 1. A Coronal proton density image (TR 2500/TE 20) through the proximal end of the right fibula demonstrates a lcsion arising from the lateral mctaphysis, one centimeter distal to the level of the epiphyseal plate. B Coronal T-2 weighted image (TR 2500/TE 80) shows a well-defined high signal cartilaginous cap covering the lesion Fig. 2. Axial T-1 weighted image (TR 600/TE 20). The peroneal nerve itself is not identified with certainty on the image, This is not surprising, as the nerve was found to be thin and splayed at surgery. However, the sequelae of peroneal nerve entrapment are clearly demonstrated. All of the visualized muscles of the anterior and lateral compartments are small with evidence of fatty infiltration. The atrophied muscles themselves are low in signal intensity. As suggested by the EMG study, the peroneus longus and brevis arc involved to a lcsser extent than the anterior compartment muscles Clinical information

Complete regression of intracranial arteriovenous malformations.

BACKGROUND Spontaneous and complete regression of intracranial arteriovenous malformations (AVMs) is a rare occurrence, with only 59 angiographically proven cases reported in the English literature. We present three new cases and perform a literature review to determine possible mechanisms underlying this unusual phenomenon. METHODS Three patients with angiographically proven AVMs demonstrated complete obliteration of the AVM on follow-up angiography. Two patients had MRIs performed at the time of follow-up angiography. RESULTS A literature review of all reported cases shows that the vast majority (88%) of spontaneously closing AVMs had a single draining vein as did our three cases. In addition, hemodynamic alterations of intracranial (IC) blood flow, including intracranial hemorrhage, were seen in a majority (79%) of patients, including two of our three cases. MRI was performed in two of our three cases and showed a thrombosed-draining vein in both. CONCLUSIONS Complete spontaneous regression of intracranial AVMs is a rare occurrence. The phenomenon seems to require the interaction of hemodynamic changes in compromising or closing the limited, usually single, venous drainage pathway from the AVM. Hemorrhage may contribute to the effect by further compromising flow though the lesion, or it may merely be a phenomenon associated with the effects of venous hypertension on the AVM nidus.

Cranial Nerve Schwannomas: Diagnostic Imaging Approach

Schwannomas are benign nerve sheath tumors that may arise along the complex course of the cranial nerves (CNs), anywhere in the head and neck. Sound knowledge of the CN anatomy and imaging features of schwannomas is paramount for making the correct diagnosis. In this article, we review approaches to diagnosing CN schwannomas by describing their imaging characteristics and the associated clinical presentations. Relevant anatomic considerations are highlighted by using illustrative examples and key differential diagnoses categorized according to regions, which include the anterior skull base, orbit, cavernous sinus, basal cisterns, and neck. The clinical presentations associated with CN schwannomas vary and range from no symptoms to symptoms caused by mass effect or CN deficits. Individuals with the inherited disorder neurofibromatosis type 2 are predisposed to multiple schwannomas. When a lesion follows the course of a CN, the radiologists roles are to confirm the imaging features of schwannoma and exclude appropriate differential considerations. The characteristic imaging features of CN schwannomas reflect their slow growth as benign neoplasms and include circumscribed margins, displacement of local structures, and smooth expansion of osseous foramina. These neoplasms exhibit various degrees of solid enhancement, often with internal cystic spaces on magnetic resonance (MR) and computed tomographic (CT) images and heterogeneous high signal intensity specifically on T2-weighted MR images. Clinical and/or imaging evidence of end-organ compromise of the involved CN may exist and aid in the identification of the nerve of origin. With a detailed understanding of the course of the CNs, the diagnostic features of CN schwannomas, and the correlation between these data and the associated clinical presentations of these tumors, the radiologist can have a key role in the diagnosis of CN schwannomas and the treatment planning for affected patients. (©)RSNA, 2016.