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The oculomotor nerve is the third cranial nerve, exiting the brainstem in the medial border of the cerebral peduncle, from where it crosses straight to the superior orbital fissure. It is a purely motor nerve responsible for the innervation of all the extraocular muscles, except the superior oblique and lateral rectus muscles. It also has parasympathetic pre-ganglionic fibers, responsible for the innervation of sphincter pupillae and ciliary muscles. Magnetic resonance imaging (MRI) is the best imaging exam to evaluate patients with clinical signs of third cranial nerve palsy. The oculomotor nerve can be affected by several diseases, such as congenital malformations, trauma, inflammatory or infectious diseases, vascular disorders, and neoplasms. This article aims to review the oculomotor nerve anatomy, discuss the best MRI techniques to evaluate each nerve segment, and demonstrate the imaging aspect of the diseases that most commonly affect it.

Arboviruses are zoonotic RNA viruses maintained in nature in cycles that involve arthropod vectors. The arboviruses that cause disease in humans are members of the Bunyaviridae, Togaviridae, Flaviviridae, and Reoviridae families. These viral species have geographically and climatically restricted distributions due to particular ecological and vector features. The main emerging arboviruses in the Americas are dengue, zika, yellow fever (Flaviviridae), and chikungunya (Togaviridae). All of these viruses can be transmitted by the Aedes aegypti and Aedes albopictus mosquitoes. Although not commonly, these infections are associated with neurological complications, characterized mainly by hemorrhage, encephalitis, myelitis, acute disseminated encephalomyelitis, Guillain-Barré syndrome, and/or congenital malformations. This review describes the imaging features of the neurological complications of these emerging arbovirus infections.

Although vaccination against Coronavirus disease-2019 (COVID-19) is still occurring, several adverse effects temporally related to these vaccines are already being reported, even if through isolated case reports. In the present study, we describe the lesions seen on magnetic resonance imaging (MRI) of three patients who developed neurological symptoms after receiving the ChAdOX1 nCoV-19 vaccine (Oxford/AstraZeneca). The first patient presented with an ischemic stroke in the posterior limb of the left internal capsule, two days after vaccination. The second patient presented with a left facial nerve palsy, seven days after vaccination. The third patient presented with myelitis, eight days after receiving the vaccine. All patients presented the symptoms after the first dose of the vaccine and did not have a history of previous COVID-19. The real incidence of these types of complications is not known yet, but it is important to consider the possibility of COVID-19 vaccine complications, in patients with a recent history of vaccination and recent development of neurological symptoms, even though this association is only casual. Longitudinal studies are necessary to further analyze the incidence of the adverse effects of each vaccine against SARS-CoV-2.

Sjögren's syndrome can be complicated by several neurological manifestations, including aseptic meningitis, which can be manifested with headache, flu-like symptoms, confusion, fever, signs of meningeal irritation, with or without focal neurological symptoms and cranial nerve palsy. Neuroimaging can reveal contrast enhancement in the lepto- or pachymeninges. Therefore, Sjögren's syndrome should be considered in the differential diagnosis of lepto- or pachymeningeal enhancement.

The trigeminal nerve is the fifth cranial nerve and is a sensory-motor nerve that provides the innervation to the face with its three roots. The trigeminal nerve can be affected by several diseases, such as vascular conflict, congenital malformation, inflammatory or neoplastic diseases. Magnetic Resonance Imaging plays a crucial role in its evaluation. This article aims to review the trigeminal nerve anatomy, discuss the best magnetic resonance imaging techniques to evaluate each nerve segment, and demonstrate the imaging aspect of the diseases that most commonly affect it.

Intra-articular osteoid osteoma may simulate arthritis, due to the intra-articular presence of prostaglandin, which leads to synovitis, joint effusion, pain, and high local temperature. Also, intra-articular osteoid osteoma may present with minimum or no cortical thickening. Therefore, a high suspicion is needed for a correct and early diagnosis. Perfusion weighted imaging, such as dynamic contrast-enhanced imaging, can aid in the localization of the tumor nidus, seen as an early arterial-phase focal enhancement after the gadolinium injection, with fast washout, as a result of its hypervascularity.

The complete features of the neurological complications of coronavirus disease 2019 (COVID-19) still need to be elucidated, including associated cranial nerve involvement. In the present study we describe cranial nerve lesions seen in magnetic resonance imaging (MRI) of six cases of confirmed COVID-19, involving the olfactory bulb, optic nerve, abducens nerve, and facial nerve. Cranial nerve involvement was associated with COVID-19, but whether by direct viral invasion or autoimmunity needs to be clarified. The development of neurological symptoms after initial respiratory symptoms and the absence of the virus in the cerebrospinal fluid (CSF) suggest the possibility of autoimmunity.

Neurologic complications are being recognized as important outcomes of coronavirus disease 2019 (COVID-19). Pathogenesis is varied and incompletely understood, and may include neuroinvasion, indirect post-infectious neuroinflammation, and cerebrovascular pathologies. We present a case of COVID-19-related encephalomyeloradiculitis with clinical and magnetic resonance imaging characteristics of neuromyelitis optica spectrum disorders that was associated with anti-aquaporin-4 antibodies. Our case suggests post-infectious autoimmunity as a mechanism in at least a subset of patients with COVID-19-related neurologic disease.

Since 2005, it has been known that mother-to-child transmission of the chikungunya virus is possible. Transmission generally occurs in the perinatal period. In the present study, we describe the brain lesions seen on MR imaging of 6 cases of perinatal chikungunya infection. Patients who underwent brain MR imaging in the acute phase presented with areas of restricted diffusion in the white matter, suggesting a perivascular distribution, whereas those in the subacute/late phase showed cystic lesions, also with a perivascular distribution, with or without brain atrophy. One patient also presented with scattered hemorrhages in the frontal and parietal lobes. Important differential diagnoses include rotavirus, Parechovirus, herpes simplex infection, and hypoxic-ischemic encephalopathy, depending on the disease phase.

To report the computed tomography (CT) features of acute cerebrovascular complications in severely ill patients with confirmed coronavirus disease 2019 (COVID-19) in the intensive care unit.We conducted a retrospective analysis of 29 intensive care unit patients with confirmed COVID-19 who underwent CT of the brain. We describe the CT features of the cerebrovascular complications of COVID-19, as well the demographic characteristics and clinical features, together with the results of laboratory tests, such as complete blood cell count, coagulation testing, renal function testing, and C-reactive protein assay.Two patients were excluded because of brain death. Among the remaining 27 patients, CT revealed acute cerebrovascular complications in six (three men and three women; 49-81 years of age), whereas no such complications were seen in 21 (15 men and six women; 36-82 years of age).Radiologists should be aware of the risks of cerebrovascular complications of COVID-19 and the potential underlying etiologies. COVID-19-associated coagulopathy is likely multifactorial and may increase the risk of ischemic and hemorrhagic infarction.Relatar as características da tomografia computadorizada (TC) das complicações cerebrovasculares agudas em pacientes com doença do coronavírus 2019 (COVID-19) grave, internados em unidade de terapia intensiva.Foi realizada análise retrospectiva de 29 pacientes com COVID-19 confirmada, internados em unidade de terapia intensiva, que realizaram TC de crânio. Descrevemos as alterações tomográficas das complicações cerebrovasculares, bem como as características demográficas, clínicas e exames laboratoriais, tais como hemograma completo, teste de coagulação, função renal e proteína C reativa desses pacientes.Seis pacientes (três homens e três mulheres; faixa etária de 49-81 anos) apresentaram alterações cerebrovasculares reveladas por TC e 21 pacientes (15 homens e 6 mulheres; faixa etária de 36-82 anos) não apresentaram complicações cerebrovasculares agudas. Dois pacientes foram excluídos por morte encefálica.Os radiologistas devem estar cientes dos riscos de complicações cerebrovasculares da COVID-19 e das possíveis etiologias subjacentes. A coagulopatia relacionada à COVID-19 é provavelmente multifatorial e pode aumentar os riscos de infarto isquêmico e hemorrágico.

The term congenital Zika syndrome (CZS) describes the spectrum of fetal and/or newborn findings associated with maternal-fetal Zika virus (ZIKV) transmission. Since 2015, congenital ZIKV infection is linked to microcephaly. Although microcephaly is the hallmark of CZS, not all affected fetuses have microcephaly. There is a wide range of other signs of this syndrome, including brain atrophy, malformations of cortical development, dysgenesia of the corpus callosum, hypoplasia of the cerebellum and cerebellar vermis, eye abnormalities, and arthrogryposis. Congenital transplacental transmission may happen at any time during pregnancy, as well as during the delivery, and there is an association between the time of ZIKV infection during the pregnancy and the severity of congenital malformations. Different imaging modalities, both prenatally and postnatally, are important to evaluate and follow up vertically ZIKV-infected patients.

Severe neurologic complications are associated with Zika virus (ZIKV) infection. Congenital Zika syndrome (CZS) results from vertical transmission of ZIKV from an infected woman to the fetus during pregnancy. The viral transmission occurs through the placenta. The neurological complications of CZS are caused by affection of the neural stem cells by the virus. CZS is characterized by severe microcephaly; decreased brain volume, with parenchymal calcifications; damage to the back of the eye; congenital contractures; and hypertonia. Prenatal and postnatal imaging, particularly magnetic resonance imaging, has a prominent role in detecting microcephaly, brain calcifications, ventriculomegaly, and malformations of cortical development. Neurological complications of postnatal acquired ZIKV infection are also known, such as Guillain-Barre syndrome (GBS), encephalitis, myelitis, and acute disseminated encephalomyelitis (ADEM). Although there is no specific imaging finding to distinguish GBS, encephalitis, myelitis, and ADEM secondary to ZIKV to their other causes, the combination of typical imaging finding and clinical history may lead to suspect of ZIKV infection as the pathogenic agent.

Zika virus (ZIKV) infection is associated with a number of neurological complications, in adults and older children, such as Guillain-Barre syndrome, encephalitis/meningoencephalitis, myelitis, and acute disseminated encephalomyelitis (ADEM). ADEM is an immune-mediated inflammatory demyelinating disorder of the central nervous system (CNS), predominantly affecting the white matter of the brain and spinal cord. Clinically, it is characterized by new-onset multifocal neurologic symptoms, including encephalopathy, with neuroimaging evidence of multifocal white matter inflammatory demyelinating lesions. Classically, ADEM is considered a monophasic illness, with highest incidence in early childhood. Magnetic resonance imaging (MRI) is the main imaging technique to diagnose ADEM. The typical MRI findings of ADEM are widespread, bilateral, asymmetric irregular lesions with hyperintense signal on T2-weighted imaging and fluid-attenuated inversion recovery (FLAIR), within the white matter (mainly the juxtacortical white matter), gray matter (typically the basal ganglia), and spinal cord. The lesions vary from small and round to large, amorphous, and irregular. Contrast enhancement is variable and nonspecific. A longitudinal extensive transverse myelitis is commonly seen in ADEM. The lesions usually appear simultaneously with clinical presentation. There is no specific imaging finding for ZIKV-related ADEM to distinguish it from other causes of ADEM.

Melanoma is a malignant neoplasm of melanin-producing cells. Melanoma usually occurs in the skin, but can also arise in any anatomical site that contains melanocytes, such as mucous membranes, the eyes, and the central nervous system (CNS). Primary CNS malignant melanoma most often develops in the leptomeninges. We report a case of a rare intramedullary melanoma of the thoracic spinal cord. A 78-year-old man was treated with surgery, radiotherapy, and immunotherapy for leptomeningeal spread. We also discuss the role of imaging methods in diagnosis and follow-up. Medullary melanoma occurs more frequently in adults. The most common presenting symptoms are the insidious onset of lower extremity weakness and paresthesia. Magnetic resonance imaging is the method of choice for evaluation. Although there are no imaging features to accurately distinguish primary malignant melanoma from other melanocytic or hemorrhagic tumors, hyperintensity on T1-weighted magnetic resonance imaging should lead to inclusion of this neoplasm in differential diagnosis of spinal cord tumors. Positron emission tomography-computed tomography is a useful auxiliary examination to evaluate the extent of local and metastatic disease. Surgical resection is the primary treatment for intramedullary melanoma. However, the efficacy of adjunctive radiotherapy and chemotherapy for primary spinal cord malignant melanoma is still controversial.