MRI Diagnosis of Clival Cancer and Sixth Nerve Palsy.

BACKGROUND: Imaging diagnosis of clival cancer may be difficult, in part because of normal variation in marrow signal with aging. Identifying whether clival cancer has damaged the sixth cranial nerve is a further challenge because minimal clival abnormalities could impinge on the nerve, which travels very close to the clivus. METHODS: Two neuroradiologists, who were unaware of previous imaging and clinical diagnoses, reviewed MRI studies of 25 patients with cancer but no clival involvement and no sixth nerve palsy, 24 patients with clival cancer but without sixth nerve palsy, and 31 patients with clival cancer and sixth nerve palsy. The radiologists were tasked with determining whether there was clival cancer, whether there was a sixth nerve palsy and its laterality, and with indicating the pulse sequences used to make those determinations. RESULTS: Both neuroradiologists correctly identified all 25 cases with a normal clivus. In about half of those cases, they depended on finding a homogeneously bright marrow signal; in the remaining cases, they excluded cancer by determining that the clivus was not expanded and that there were no focal signal abnormalities. Both neuroradiologists correctly identified clival cancer in 54 (98%) of the 55 cases with and without sixth nerve palsy. In doing so, they relied mostly on clival expansion but also on focal signal abnormalities. Both neuroradiologists were at least 80% correct in identifying a sixth nerve palsy, but they often incorrectly identified a palsy in patients who did not have one. When there was a one-sided signal abnormality or the clivus was expanded in one direction, both neuroradiologists were accurate in identifying the side of the sixth nerve palsy. CONCLUSION: Current MRI pulse sequences allow accurate differentiation of a normal from a cancerous clivus. When the marrow signal is not homogeneously bright in adults, cancer can be diagnosed on the basis of clival expansion or focal signal abnormalities. MRI is less accurate in predicting the presence of a sixth nerve palsy. However, the side of a unilateral palsy can be predicted when the clivus is clearly expanded in one direction or there is a focal signal abnormality on one side.

Presenting Symptoms and Imaging Features of Posterior Cerebral Artery Stroke Causing Homonymous Hemianopia.

BACKGROUND: Posterior cerebral artery (PCA) stroke is a common cause of homonymous hemianopia and other neurologic deficits associated with more proximal ischemia in the vertebrobasilar circuit. Localization of the process can be challenging unless the symptom complex is well recognized, yet early diagnosis is critical to forestall dangerous driving and repeated stroke. We undertook this study to provide additional detail about the presenting symptoms and signs and their correlation with imaging abnormalities and stroke etiology. METHODS: Retrospective study of medical records of patients presenting to a single tertiary care academic center between 2009 and 2020 with homonymous hemianopia from PCA stroke. We excerpted data on symptoms, visual and neurologic signs, incident medical procedures and diagnoses, and imaging features. We determined stroke etiology using the Causative Classification Stroke system. RESULTS: In a cohort of 85 patients, 90% of strokes occurred without preceding symptoms. But in retrospect, 10% of strokes did have warning symptoms. In 20% of patients, strokes followed within 72 hours of a medical or surgical procedure or newly identified medical condition. In the subgroups of patients whose records contained a description of visual symptoms, 87% reported the visual sensation as negative, and 66% realized that it was located in a hemifield in both eyes. Concurrent nonvisual symptoms were present in 43% of patients, consisting commonly of numbness, tingling, and new headache. Infarction located outside the visual cortex affected primarily the temporal lobe, thalamus, and cerebellum, reflecting the widespread nature of ischemia. Nonvisual clinical manifestations and arterial cutoffs on imaging were associated with thalamic infarction, but the clinical features and location of the infarction did not correlate with the etiology of the stroke. CONCLUSIONS: In this cohort, clinical localization of the stroke was aided by the fact that many patients could lateralize their visual symptoms and had nonvisual symptoms suggestive of ischemia affecting the proximal vertebrobasilar circuit. Numbness and tingling were strongly linked to concurrent thalamic infarction. Clinical features and infarct location were not associated with the etiology of the stroke.

Demographics, Risk Factors, and Etiology of Posterior Cerebral Artery Stroke Causing Homonymous Hemianopia.

BACKGROUND: Posterior cerebral artery (PCA) strokes account for up to 10% of all ischemic strokes, often presenting with homonymous hemianopia. The proportion of these strokes attributed to various etiologies varies widely in previously published studies, owing largely to differing patient populations, definitions of stroke pathogenesis, and vascular territories involved. The Causative Classification System (CCS), an automated version of the Stop Stroke Study (SSS) Trial of Org 10,172 in Acute Stroke Treatment (TOAST) system, allows for a more rigorous assignment of stroke etiology. METHODS: We excerpted clinical and imaging data on 85 patients who had PCA stroke with homonymous hemianopia examined at the University of Michigan. We compared the stroke risk factor profile of our PCA cohort with that of 135 patients with stroke in the distribution of the internal carotid artery (ICA) and middle cerebral artery (MCA) in an unpublished University of Michigan registry. We applied the CCS web-based calculator to our PCA cohort to determine stroke etiology. RESULTS: In our PCA cohort, 80.0% had at least 2 conventional stroke risk factors and 30.6% had 4 risk factors, most commonly systemic hypertension. The risk factor profile of our PCA cohort resembled that of our ICA/MCA cohort except that the mean age of our PCA cohort was more than a decade younger and had a significantly lower frequency of atrial fibrillation (AF) than our ICA/MCA cohort. In nearly half of the patients with AF in our PCA cohort, AF was diagnosed after the stroke. Among stroke etiologies in our PCA cohort, 40.0% were of undetermined cause, 30.6% were from cardioaortic embolism, 17.6% were from other determined causes, and only 11.8% were from supra-aortic large artery atherosclerosis. Strokes after endovascular or surgical interventions were prominent among other determined causes. CONCLUSIONS: Most patients in our PCA cohort had multiple conventional stroke risk factors, a finding not previously documented. Mean age at stroke onset and AF frequency were lower than in our ICA/MCA cohort, in agreement with previous studies. As some other studies have found, nearly 1/3 of strokes were attributed to cardioaortic embolism. Within that group, AF was often a poststroke diagnosis, a finding not previously highlighted. Compared with earlier studies, a relatively high portion of strokes were of undetermined etiology and of other determined etiologies, including stroke after endovascular or surgical interventions. Supra-aortic large artery atherosclerosis was a relatively uncommon explanation for stroke.

Impact of Diplopia and Ptosis From Lingering Third Nerve Palsy After Treatment of Cerebral Aneurysms.

BACKGROUND: Third nerve palsies (TNPs) may not resolve after intervention for intracranial aneurysms that have compressed the nerve. The disability related to this lingering condition has not been assessed with the support of patient self-report. METHODS: A single-institutional retrospective study of patients with TNP who had undergone interventions for intracranial aneurysms. We used residual primary-position diplopia, a narrow zone of single binocular vision, and vision-obscuring ptosis to divide TNP recovery into complete, incomplete nondisabling, and incomplete disabling outcomes based on medical record documentation and patient self-report derived from telephonic interviews. RESULTS: In a cohort of 33 patients, 13 (39%) had complete TNP recovery. There were 11 patients (33%) with lingering visual disability from diplopia or ptosis present before ophthalmic interventions. Of the 6 patients who underwent ophthalmic interventions, visual disability was relieved in only 2 patients, leaving 9 patients (27%) with lingering impairment in instrumental activities of daily living. Telephonic interviews of 23 patients (70% of the cohort) confirmed that the outcome criteria we applied were accurate in assessing visual disability in 17 patients (74%). Univariate analysis using the Fisher exact test showed that aneurysmal clipping as a treatment modality was the only clinical feature associated with a favorable TNP outcome. CONCLUSIONS: In applying a novel method of assessing disability, this study showed that more than one-quarter of patients undergoing procedures for brain aneurysms had lingering disability from third nerve palsy-associated diplopia or ptosis, despite later ophthalmic interventions. Patient self-report gleaned from telephonic interviews was valuable in largely validating the assessment method derived from medical records and in revealing differences between physician and patient estimation of disability.

A Teenage Boy With a Radiation-Induced High-Grade Astrocytoma.

ABSTRACT: A 12-year-old boy developed acute headache and vomiting. MRI brain showed a partially cystic suprasellar mass. He underwent cyst fenestration, but the cyst regrew, so he underwent transcranial subtotal resection of the mass. The pathologic diagnosis was adamantinomatous craniopharyngioma. Residual tumor was treated with proton beam radiation therapy, and panhypopituitarism was treated with hormone replacement therapy, including growth hormone. Serial brain MRI scans over several years showed no evidence of tumor recurrence. But at four years after radiation, surveillance MRI showed a new focus of nonenhancing FLAIR hyperintensity in the left basal ganglia attributed to gliosis caused by radiotherapy. Seven months later, he developed progressive right hemiparesis, expressive aphasia, and blurred vision, prompting reevaluation. MRI brain showed new enhancing and T2/FLAIR hyperintense lesions in the midbrain, basal ganglia, thalamus, anterior temporal lobe, and optic tract. The abnormal regions showed low diffusivity and relatively high regional blood flow. Stereotactic biopsy disclosed a WHO Grade 4 astrocytoma, likely radiation-induced. A germline ataxia telangiectasia mutation was found in the tumor tissue. The risk of radiation-induced pediatric brain malignancies is low but may have been increased by the mutation.

Deadly Fungi: Invasive Fungal Rhinosinusitis in the Head and Neck.

Invasive fungal rhinosinusitis (IFRS) is a serious infection that is associated with high morbidity and mortality rates. The incidence of IFRS has been increasing, mainly because of the increased use of antibiotics and immunosuppressive drugs. Rhino-orbital cerebral mucormycosis has recently reemerged among patients affected by COVID-19 and has become a global concern. The detection of extrasinus involvement in its early stage contributes to improved outcomes; therefore, imaging studies are essential in establishing the degree of involvement and managing the treatment properly, especially in immunocompromised patients. The common sites of extrasinus fungal invasion are the intraorbital, cavernous sinus, and intracranial regions. Fungi spread directly to these regions along the blood vessels or nerves, causing devastating complications such as optic nerve ischemia or compression, optic neuritis or perineuritis, orbital cellulitis, cavernous sinus thrombosis, mycotic aneurysm, vasculitis, internal carotid arterial occlusion, cerebral infarction, cerebritis, and brain abscess. IFRS has a broad imaging spectrum, and familiarity with intra- and extrasinonasal imaging features, such as loss of contrast enhancement of the affected region, which indicates tissue ischemia due to angioinvasion of fungi, and the surrounding anatomy is essential for prompt diagnosis and management. The authors summarize the epidemiology, etiology, risk factors, and complications of IFRS and review the anatomy and key diagnostic imaging features of IFRS beyond the sinonasal regions. ©RSNA, 2022.

Retinal, Optic Nerve, and Cerebral Infarction in Odontogenic Lemierre Syndrome.

ABSTRACT: A 61-year-old healthy woman developed congestive orbitopathy, and bilateral retinal, optic nerve, and cerebral infarctions after removal of a chipped molar tooth. Ophthalmoscopy disclosed multiple retinal arteriolar occlusions and pallid swelling of both optic discs. Imaging revealed ipsilateral masticator and pterygoid muscle abscesses, and thrombosis of the right internal jugular vein and sigmoid sinus, both cavernous sinuses and superior ophthalmic veins, and restricted diffusion of both optic nerves and corona radiata. Blood cultures were positive for Streptococcus anginosus. Despite aggressive medical and surgical treatment, the patient remained unresponsive and presumptively blind. This case is an example of a catastrophic form of odontogenic Lemierre syndrome. Blindness, attributable to venous hypertension and vasculitis, has been rarely reported. Early recognition and treatment are critical to avoid such dire consequences.

Visual Field Defect Patterns Associated With Lesions of the Retrochiasmal Visual Pathway.

BACKGROUND: Perimetry is widely used in the localization of retrochiasmal visual pathway lesions. Although macular sparing, homonymous paracentral scotomas, and quadrantanopias are regarded as features of posterior retrochiasmal visual pathway lesions, incongruous hemianopia is regarded as a hallmark of anterior lesions. Recent studies have questioned the specificity of these defect patterns. METHODS: Retrospective record review conducted in a single, academic, medical center using an electronic search engine with the terms ""homonymous hemianopia," "optic tract," "temporal lobectomy," "visual field defect," and "MRI." Patients were included if they had reliable, automated, static visual fields, high-quality reviewable MRI scans, and pertinent lesions. MRI lesions were assigned to 1 of 6 retrochiasmal visual pathway segments by the study neuroradiologist. Two study authors independently reviewed the visual fields and designated 10 different defect patterns. RESULTS: From an original cohort of 256 cases, only 83 had MRI-defined lesions that were limited to particular retrochiasmal segments and had visual field defect patterns that allegedly permitted localization to those particular segments. The 5 contralateral nerve fiber bundle defects were exclusive to optic tract tumors with rostral extension. Pie-in-the-sky defects were exclusive to Meyer loop lesions. Among 22 fields with macular sparing, 86% arose from the visual cortex or posterior optic radiations. Among 31 fields with homonymous quadrantanopias, 77% arose from Meyer loop, visual cortex, or posterior optic radiations. Among 13 fields with homonymous paracentral scotomas, 69% arose from visual cortex or posterior optic radiations. Optic tract lesions accounted for 70% of incongruous hemianopias but that pattern occurred uncommonly. CONCLUSION: In correlating discrete MRI-defined retrochiasmal lesions with visual field defect patterns identified on static perimetry, this study showed that macular sparing, homonymous paracentral scotomas, and quadrantanopias localized to the visual cortex and posterior optic radiations segments but not exclusively. It has differed from an earlier study in showing that incongruous hemianopias occur predominantly from optic tract lesions.

Accuracy of Visual Fields in Localizing MRI Lesions in Posterior Cerebral Artery Infarction.

BACKGROUND: The representation of the visual field in visual cortex was established over a century ago by correlating perimetric defects with the estimated location of war wounds. The availability of high-definition MRI offers the possibility of more precise correlation. METHODS: Homonymous hemianopias disclosed on automated visual fields (HVFs) were drawn from an electronic medical record search from 2009 to 2020 at the Michigan Medicine, a tertiary care academic medical center. The patterns of the visual field defects (VFDs) were interpreted by a consensus of 2 authors. The VFDs were correlated with the location of MRI lesions in 92 patients with posterior cerebral artery (PCA) domain ischemic strokes, as determined by the neuroradiologist author, who was masked as to the VFDs. RESULTS: Among the 77 VFDs confined to 1 hemifield, 74 (96%) correctly predicted the side of the visual cortex lesion. In 3 cases, the MRI lesion in the opposite cerebral hemisphere was not foretold. Among the 15 VFDs present in both hemifields, 5 (33.3%) overestimated the MRI lesions, which were evident in only 1 hemisphere. Among the 30 VFDs confined to 1 quadrant, 29 (97%) correctly predicted the lesioned visual cortex quadrant. However, 14 VFDs failed to predict MRI lesions present in both superior and inferior visual cortex quadrants on the same side. Those unpredicted lesions mostly had subtle or indistinct signal abnormalities or were confined to anterior visual cortex, an area that is inaccessible with the HVF test protocol used in this study. CONCLUSION: In this study of PCA ischemic stroke, VFDs limited to 1 hemifield were accurate in locating the side and quadrant of the MRI visual cortex lesions. However, the quadrantic VFDs sometimes failed to predict that the lesions involved both the superior and inferior quadrants on the same side, largely because those lesions had subtle imaging features that defied accurate radiologic assessment or were out of the reach of the visual field test protocol.

Correlation of Macular Sparing and Homonymous Paracentral Scotomas With MRI Lesions in Posterior Cerebral Artery Infarction.

BACKGROUND: The concepts of the representation of visual field in primary visual cortex are based on studies of war wounds and correlations with brain imaging in small cohorts. Because of the difficulty of judging brain lesion extent and the small number of studied patients, there is lingering controversy as to whether the central 15° of visual field are mapped onto the posterior 25% of primary visual cortex or onto a larger area. To improve the delineation of MRI lesion extent, we have studied only patients with posterior cerebral artery (PCA) ischemic strokes. METHODS: We accrued a cohort of 92 patients with PCA strokes from an electronic medical records search between 2009 and 2020 at a single tertiary care academic institution. Patients had reliable static perimetry demonstrating homonymous hemianopias and high-definition reviewable brain imaging. We divided the primary visual cortex on the MRI T1 sagittal sequence into 8 equal segments in right and left cerebral hemispheres and located lesions according to the segments they occupied. We correlated lesion locations with 3 visual field defects (VFDs): macular-sparing homonymous quadrantanopias, macular-splitting homonymous quadrantanopias, and homonymous paracentral scotomas. RESULTS: Among 25 cases with macular sparing, 13 had lesion-sparing confined to the posterior 25% of visual cortex. Among 6 cases with homonymous paracentral scotomas, 2 had lesions confined to the posterior 25% of visual cortex. Macular-splitting quadrantanopia did not occur in any patients with lesions confined to the posterior 25% of visual cortex, but did occur in 3 patients with lesions confined to the posterior 50% of visual cortex. These phenomena would not be expected if the central 15° of visual field were mapped onto a region extending beyond the posterior 25% of visual cortex. In patients with PCA strokes that involved the retrogeniculate visual pathway proximal to visual cortex, the visual cortex lesions were often less extensive than predicted by the VFDs, perhaps because of widespread damage to axons before they reached their destination in visual cortex. CONCLUSIONS: These results support the concept that the central 15° of the visual field are represented in the posterior 25% of visual cortex. Although this study contributes a larger cohort of patients with better-defined lesion borders than in past reports, its conclusions must be tempered by the variability of patient attention during visual field testing, the subjectivity in the interpretation of the defect patterns, and the difficulty in judging MRI lesion extent even on diffusion-weighted and precontrast T1 sagittal sequences.

Evaluation of Diplopia by Emergency Medicine Physicians and Consulting Neurologists.

BACKGROUND: Appropriate evaluation of diplopia requires separating serious from benign causes. If providers are not adept in this task, diagnosis of critical conditions may be delayed and unnecessary testing may result. METHODS: We studied the records of 100 consecutive patients who presented to an emergency department between 2010 and 2020 with diplopia as a prominent symptom. We rated the performance of emergency medicine physicians (EMPs) and consulting neurologists (CNs) in the examination, diagnosis, and ordering of diagnostic tests according to standards based on neuro-ophthalmologic consultation and the neuro-ophthalmologic literature. RESULTS: EMPs made no diagnosis or an incorrect diagnosis in 88 (88%) of 100 encounters. They ordered 14 unindicated and 12 incorrect studies, mostly noncontrast computed tomography scans. CNs made an incorrect diagnosis in 13 (31%) encounters. They ordered 6 unindicated and 2 incorrect studies. The total charge for unindicated and incorrect studies ordered by EMPs and CNs was $119,950. CONCLUSIONS: EMPs and CNs made frequent errors in the examination, diagnosis, and ordering of diagnostic studies, leading to inefficient care and unnecessary testing. EMPs largely delegated the evaluation of diplopia to their consultants. If such consultative support were not available, the care of diplopic patients would be delayed. CNs performed more complete examinations, but rarely enough to allow appreciation of the pattern of ocular misalignment, contributing to misdiagnoses and ordering errors. The identification of these provider errors allows for more targeted teaching in the evaluation of diplopia.

The Clinical and Imaging Profile of Skew Deviation: A Study of 157 Cases.

BACKGROUND: Skew deviation, a vertical misalignment of the eyes caused by a lesion in the vestibulo-ocular pathway, is a common manifestation of brainstem dysfunction, yet comprehensive information about its clinical profile is lacking. The aim of this study was to document presenting symptoms, causes, ocular alignment features, accompanying neurologic signs, pertinent brain imaging abnormalities, and measures used to relieve diplopia. METHODS: We searched the electronic medical records text from 2000 to 2018 for "skew" or "skew deviation" at a tertiary care academic center, including only patients diagnosed under supervision of faculty neuro-ophthalmologists. After excluding patients with features suggesting an imitator of skew deviation, we collected data useful in answering the selected clinical issues. RESULTS: In a cohort of 157 patients, vertical misalignment ranged between 1 and 30 prism diopters (PD) (median 5 PD) and was comitant in 100 (64%) patients. Diplopia was reported by 87% and blurred vision by 11% of patients. Blurred vision was more common when vertical misalignment was less than 3 PD. At least one accompanying neurologic sign was present in 133 (85%) patients, most often nystagmus, followed by gaze paresis, ataxia, saccadic pursuit, and internuclear ophthalmoplegia. Stroke affecting the thalamus, brainstem, or cerebellum accounted for 82 (52%) of cases. Stroke was usually ischemic, mostly unprovoked, but also occurring after intracranial or extracranial surgical procedures. Brainstem tumor and operative injury caused most of the remaining cases. A subgroup of 17 (11%) patients had skew deviation as the only new clinical sign and had no pertinent brain imaging abnormalities. Resolution of skew deviation, documented in 58 (42%) of 137 patients who had at least one follow-up visit, usually occurred within 3 months, but sometimes not until after 12 months. Of 110 patients who still had diplopia on follow-up examinations, the diplopia was successfully relieved with prism spectacles in 68 (62%). The cause of the skew deviation, amount of vertical misalignment, and degree of incomitance did not predict the success in relieving diplopia. Accompanying neurologic signs, including ataxia, endured in 44% of patients and were often more debilitating than the diplopia of skew deviation. CONCLUSIONS: The amplitude of misalignment in skew deviation varies widely but is generally 5 PD or less. When misalignment is 3 PD or less, patients report blurred vision rather than diplopia. Skew deviation is usually accompanied by other neurologic signs reflecting brainstem dysfunction. Yet there is a small subgroup in which vertical misalignment is an isolated sign, and there are no supporting brain imaging abnormalities. The main cause of skew deviation is ischemic stroke, which affects not only the brainstem but also the thalamus. Diplopia from skew deviation frequently persists, in which case prism spectacles may be successful in palliating it. Accompanying neurologic signs, especially ataxia, may outlast skew deviation and be more debilitating.

Complications of Ventriculoperitoneal Shunt for Idiopathic Intracranial Hypertension: A Single-Institution Study of 32 Patients.

BACKGROUND: Because there are no head-to-head studies of the efficacy of surgical options in the treatment of medically-intractable idiopathic intracranial hypertension (IIH), procedure selection is often based on expected complications. Cerebrospinal fluid (CSF) diversion by shunting has been reported to have a 23%-67% rate of shunt failure. But these figures derive from small cohorts or studies that do not separate the complication rates of the different shunt options-ventriculoperitoneal (VP), lumboperitoneal (LP), and ventriculoatrial (VA). The complication rate of LP shunts seems to be higher than that for VP shunts, the procedure currently in widest use. Our experience with VP shunts for IIH over the past decades suggests that the complication rate for that option is lower than reported series would suggest. METHODS: Retrospective single-institutional study using a search engine that finds all text mentions of particular terms. We searched for the terms ("IIH" OR "Idiopathic intracranial hypertension" OR "PTC OR "pseudotumor") AND ("VP Shunt" OR "ventriculoperitoneal") over the period 1998 to 2018. From 490 "hits," only 32 patients met entry criteria: diagnosis of IIH confirmed at our institution, including examination in a neuro-ophthalmology clinic showing papilledema, elevated opening pressure on lumbar puncture or a consistently elevated intraparenchymal pressure on Codman intracranial pressure (ICP) monitoring, neuroimaging and CSF studies consistent with a diagnosis of IIH, and at least 1 year of follow-up in our neuro-ophthalmology or neurosurgery clinics. RESULTS: Shunt failures occurred in 6 (18.7%) of 32 patients, which included elevated ICP due to obstruction or discontinuity of the shunt, over-drainage, infection of the shunt system, or intractable abdominal pain or infection. None of these failures caused permanent worsening of vision, neurologic morbidity, or death. But they entailed considerable medical care. Placement of VP shunts also aroused patient fear of complications, precipitating 38 emergency visits in 14 patients for "false alarms." CONCLUSIONS: In this series of 32 patients, the largest retrospective study of VP shunts for IIH, there was an 18.7% failure rate, lower than previously published smaller series have disclosed. But among patients who suffered complications, a saga of intensive medical care often occurred. Placement of the shunt also aroused patient fear of complications, leading to many medical encounters required to rule out complications.

Dorsal Midbrain Syndrome: Clinical and Imaging Features in 75 Cases.

BACKGROUND: Dorsal midbrain syndrome (DMS) consists of a constellation of clinical features, including reduced upgaze, pupillary light-near dissociation, lid retraction, convergence retraction, and eye misalignment. This syndrome results mostly from intrinsic or extrinsic mesodiencephalic tumors or strokes, obstructive hydrocephalus, failure of cerebrospinal fluid shunting to correct obstructive hydrocephalus, and head trauma. Published reports that include imaging corroboration are based on relatively small cohorts and have not included comprehensive patient self-reports on the impact of these abnormalities on quality of life. METHODS: We conducted a retrospective review of cases of DMS identified between 1998 and 2019 at the University of Michigan using the Electronic Medical Record Search Engine. Patients were included only if they had been evaluated by a neuro-ophthalmologist and had a corroborative imaging abnormality. We collected data on symptoms and on neuro-ophthalmic and neurologic signs. We reviewed brain imaging reports on all 75 patients, and the study neuroradiologist analyzed the imaging in 57 patients. Using a uniform list of questions, we conducted telephone interviews of 26 patients to assess lingering symptoms and their impact on quality of life. RESULTS: There were 75 patients, only 5 of whom were younger than 10 years. Neoplasms accounted for 47%, strokes (mostly thalamic) for 25%, nonneoplastic masses for 12%, nonneoplastic hydrocephalus for 7%, traumatic brain injury for 5%, and demyelination for 4%. Reduced upgaze occurred in 93% of patients, being completely absent or reduced to less than 50% amplitude in 67%. Convergence retraction on attempted upgaze occurred in 52%, horizontal misalignment in 49%, vertical misalignment in 47%, and pupillary light-near dissociation in 37%. Optic neuropathy attributed to chronic papilledema occurred in only 3%. Three or more neuro-ophthalmic signs were present in 84%, and only 4% had a single sign-reduced upgaze. Imaging features did not correlate with the frequency or severity of clinical signs. There was some improvement in the clinical signs among the patients with stroke but no change among the patients with neoplasms. In the 26 telephone interviews, patients with neoplasms reported that imbalance had a greater impact on quality of life than did diplopia. Patients with strokes reported that imbalance had the greatest impact initially but that its effect dissipated. Neither group reported lingering effects of impaired upgaze. CONCLUSIONS: This large series expands on the clinical profile of DMS. Neoplasms and strokes were the most common causes. Obstructive hydrocephalus alone, identified as a major cause in the largest previously published series, was uncommon. At least 3 neuro-ophthalmic signs were present in nearly all patients, with upgaze deficit as predominant. Unlike an earlier report, this study found no correlation between brain imaging and clinical signs. Neuro-ophthalmic signs persisted even after neoplasms were successfully treated and improved only slightly after stroke. Telephone interviews with patients revealed that diplopia and upgaze deficit had less lasting impact on quality of life than did ataxia and concurrent nonneurologic problems.

Splenial Restricted Diffusion as MRI Correlate of Diaschisis in a Blind Infant With Unilateral Posterior Cerebral Artery Stroke.

ABSTRACT: A 3-month-old male infant appeared on multiple clinical examinations to have acutely developed bilateral retrogeniculate blindness. Electroencephalography showed focal status epilepticus confined to the left posterior cerebral hemisphere. MRI demonstrated restricted diffusion in the domain of the left posterior cerebral artery consistent with acute stroke. Notably, the restricted diffusion extended across the midline in the splenium of the corpus callosum. This splenial sign may be the imaging correlate of cerebral diaschisis, a well-described phenomenon in which patients with new brain lesions develop acutely impaired neurologic function in related but nonlesioned brain regions. Diaschisis has been posited as the explanation for the temporary bilateral blindness in adult patients suffering from unilateral occipital infarctions.

Imaging Errors in Distinguishing Pituitary Adenomas From Other Sellar Lesions.

BACKGROUND: Pituitary adenomas and nonadenomatous lesions in the sellar region may be difficult to distinguish by imaging yet that distinction is critical in guiding management. The nature of the diagnostic errors in this setting has not been well documented. METHODS: Two neurosurgeons and 2 neuroradiologists of differing experience levels viewed deidentified MRIs of 18 nonadenomatous sellar lesions and 21 adenomas. They recorded their diagnoses, the imaging features they used to make those diagnoses, and their confidence in making those diagnoses. RESULTS: Among the 18 nonadenoma cases, 11 (61%) were incorrectly diagnosed as adenoma by at least 1 reader, including Rathke cleft cyst, plasmacytoma, aneurysm, craniopharyngioma, chordoma, Langerhans cell histiocytosis, metastasis, and undifferentiated sinonasal carcinoma. Among the 21 adenoma cases, 8 (38%) were incorrectly diagnosed by at least 1 reader as craniopharyngioma, Rathke cleft cyst, sinonasal carcinoma, hemangioblastoma, and pituitary hyperplasia. Incorrect imaging diagnoses were made with high confidence in 13% of readings. Avoidable errors among the nonadenomatous cases occurred when readers failed to appreciate that the lesion was separate from the pituitary gland. Unavoidable errors in those cases occurred when the lesions were so large that the pituitary gland had been obliterated or the imaging features of a nonadenomatous lesion resembled those of a cystic pituitary adenoma. Avoidable errors in misdiagnosis of adenomas as nonadenomas occurred when readers failed to appreciate features highly characteristic of adenomas. An unavoidable error occurred because a cystic adenoma had features correctly associated with craniopharyngioma. CONCLUSIONS: Errors in imaging differentiation of pituitary adenoma from nonadenomatous lesions occurred often and sometimes with high confidence among a small sample of neurosurgeons and neuroradiologists. In the misdiagnosis of nonadenomatous lesions as adenomas, errors occurred largely from failure to appreciate a separate pituitary gland, but unavoidable errors occurred when large lesions had obliterated this distinguishing feature. In the misdiagnosis of adenomas as nonadenomatous lesions, avoidable errors occurred because readers failed to recognize imaging features more characteristic of adenomas and because cystic adenomas share features with craniopharyngiomas and Rathke cleft cysts. Awareness of these errors should lead to improved management of sellar lesions.

Neuro-Ophthalmologic Monitoring in the Management of Increased Intracranial Pressure From Leaking Arachnoid Cysts.

BACKGROUND: Intracranial arachnoid cysts are common incidental imaging findings. They may rarely rupture, leading to the development of subdural hygromas and high intracranial pressure (ICP). Neurosurgical intervention has been advocated in the past, but recent evidence indicates that most cases resolve spontaneously. The role of neuro-ophthalmologic monitoring in identifying the few cases that have persisting vision-threatening papilledema that justifies intervention has not been emphasized. METHODS: Retrospective review of 4 cases of leaking arachnoid cysts drawn from the files of the University of Michigan Medical Center (Michigan Medicine) between 2007 and 2018. RESULTS: In 1 case, surgery was avoidable as papilledema resolved over time despite lingering imaging features of mass effect. In 3 cases, papilledema persisted with the threat of permanent vision loss, prompting neurosurgical intervention. In one of those cases, the fluid collection was thinly but extensively spread across both hemispheres without brain shift; yet, papilledema was pronounced. Emergent evacuation led to rapid resolution of papilledema and encephalopathy, but with residual optic nerve damage. CONCLUSIONS: Because constitutional symptoms and even imaging are not always reliable indicators of high ICP in leaking arachnoid cysts, neuro-ophthalmologic monitoring of papilledema is valuable in identifying the cases when neurosurgical intervention is necessary.

Causes of Horner Syndrome: A Study of 318 Patients.

BACKGROUND: Some reports have indicated that when a cause for Horner syndrome can be determined, it is most often chest and neck tumors and stroke. Others have suggested that Horner syndrome is more frequently caused by surgical procedures in the neck and chest. These differences may be explained by disparate accrual methods. Therefore, we decided to compare the cause of Horner syndrome in cases where the diagnosis was confirmed by apraclonidine testing conducted by ophthalmologists to cases in which the diagnosis was made entirely on clinical grounds mostly by nonophthalmologists. METHODS: We applied a new search engine to the inpatient and outpatient electronic medical records text at the University of Michigan Medical Center from 1996 to 2018 for Horner syndrome with and without pharmacologic confirmation through ocular instillation of apraclonidine 0.5%. Among apraclonidine-confirmed cases, 159 met inclusion criteria. Among apraclonidine-unconfirmed cases, more than 2,000 cases were identified, so that we included only the first 159 cases that met inclusion criteria. In these 318 cases, we documented patient demographics, ophthalmologic features, imaging, underlying cause, and whether the cause was discovered before or after the diagnosis of Horner syndrome. RESULTS: In the cohort of 159 apraclonidine-confirmed cases of Horner syndrome, a cause was identified in 97 (61%). Procedures in the neck, chest, skull base, and paraspinal region accounted for most of the identified causes, with cervical carotid dissection the next most common cause. In a cohort of 159 cases of Horner syndrome not tested with apraclonidine because the clinical diagnosis appeared firm, procedures again accounted for the largest percentage, but tumor was the next most common cause. In both groups, when a cause for Horner syndrome could be identified, that cause was nearly always known before Horner syndrome was identified. However, in an important minority of cases, mostly involving carotid dissection or tumor, the identification of Horner syndrome was critical to the discovery of those conditions. CONCLUSIONS: The prevalence of causes of Horner syndrome depends on the accrual method. Among pharmacologically-confirmed cases, the cause was often undetermined or due to a preceding neck or chest procedure. Among pharmacologically-unconfirmed cases, a substantial proportion had also been caused by neck and chest procedures, but tumors in that region were also common. When a cause of Horner syndrome was found in both cohorts, it was usually known before Horner syndrome was discovered, making Horner syndrome an afterthought. However, in an important minority of cases where the cause was not yet known, the identification of Horner syndrome was valuable in leading to important diagnoses such as carotid dissection and tumor.

Catastrophic Allergic Fungal Sinusitis: A Report of Two Cases.

BACKGROUND: Allergic fungal rhinosinusitis (AFRS) is a common condition in which sinusitis develops as an IgE-mediated response to common sinonasal fungal organisms. If that response leads to blockage of sinus ostia, bone expansion and erosion by expansive cysts containing dense inspissated debris may occur with the potential for critical neurovascular compression including damage to the anterior visual pathway. METHODS: Review of clinical and imaging features of 2 patients who sustained catastrophic clinical outcomes. RESULTS: The first patient had pansinusitis with massive mucocele-like cysts expanding the sphenoid sinus and cranial base and causing compression of the anterior visual pathway that led to persistent severe vision loss despite extensive sinus surgery. The second patient developed sphenoethmoidal expansion with a marked inflammatory response and presumed conversion to invasive fungal sinusitis that caused anterior visual pathway vision loss, bilateral ocular motor palsies from extension into the cavernous sinuses, and death from a large middle cerebral artery stroke. CONCLUSIONS: Although AFRS is most often benign and treatable, it may rarely produce catastrophic outcomes, especially if the sphenoid sinus is involved. Irreversible vision loss may occur from compression, and ocular motor palsies and death from conversion to invasive fungal disease. Close ophthalmologic and imaging monitoring is necessary in patients with expanded sinuses, and prophylactic sinus surgery may be indicated in certain cases.

Isolated Fourth Nerve Palsy in Nontraumatic Tentorial Hemorrhage.

A 46-year-old woman being treated with warfarin for antiphospholipid antibody syndrome experienced a rise in international normalized ratio (INR) to 5.4 and developed sudden headache and diplopia. Neuro-ophthalmologic examination disclosed a right fourth nerve palsy. Noncontrast computed tomography revealed a subdural hematoma layered along the right tentorium cerebelli, directly in the path of the nerve. With normalization of the INR, the palsy markedly improved over subsequent weeks. This is a unique case of a nontraumatic subdural hematoma causing a fourth nerve palsy.