Spotlight on Leber hereditary optic neuropathy

In this article, Dr. Tanyatuth Padungkiatsagul of Mahidol University discusses Leber hereditary optic neuropathy, a maternally inherited bilateral optic neuropathy that typically affects teenage males with acute vision loss first in one eye and then the other within days or weeks. There are some distinctive changes in the ocular fundus appearance at various stages of the process that make specific diagnosis possible clinically. The etiology involves mutations in the mitochondrial DNA, and penetrance is incomplete. Due to the acute sequential presentation, there is a unique opportunity to study treatments that reduce risk of symptom development. There are active clinical trials underway to study gene therapy and drug therapy.

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Spotlight on Presbyosmia

In this article, Dr. Douglas Lanska of the University of Wisconsin School of Medicine and Public Health, the Medical College of Wisconsin, and IM Sechenov First Moscow State Medical University explains the clinical presentation, pathophysiology, diagnostic workup, and management of presbyosmia.

Presbyosmia (literally “elderly olfaction” or “old age olfaction”) is the gradual loss of olfactory abilities that occurs in most people as they grow older. Age-related losses of smell (presbyosmia) are common in the elderly and result from normal aging, certain diseases (especially Parkinson disease and dementia with Lewy bodies), medications, surgical interventions, and prior environmental exposures.

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Spotlight on Myositis and cancer

There is a well-recognized association between cancer and myositis, mainly seen in classic dermatomyositis, amyopathic dermatomyositis, and immune-mediated necrotizing myopathy.

Idiopathic inflammatory myopathies, referred to as “myositis,” can be associated with cancer. Classic dermatomyositis, amyopathic dermatomyositis, and, to lesser extent, polymyositis are the most highly affected myositis phenotypes, whereas immune-mediated necrotizing myopathy has been linked to cancer as a paraneoplastic phenomenon. Cancer-associated myositis is defined as the concomitant presence of the 2 diseases within a 3-year period. However, a paraneoplastic pattern—that is, when cancer abates, myositis disappears and when malignancy recurs, myositis returns—is not always observed.

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Spotlight on Fetal alcohol syndrome

Fetal alcohol syndrome is the most common preventable cause of intellectual disability in the Western world. In addition to inducing developmental delay, gestational alcohol exposure can lead to a variety of neurodevelopmental abnormalities, including epilepsy, attention deficit hyperactivity disorder, and academic difficulties. Many of these behavioral deficits in children with fetal alcohol syndrome are due to alcohol-induced neuronal death.

In this updated article, Dr. Nancy Bonthius and Dr. Daniel Bonthius of the University of Iowa discuss alcohol consumption patterns by pregnant women in the United States and how this relates to the prevalence of fetal alcohol spectrum disorders. In addition, the authors discuss the neuropathologic changes induced by prenatal alcohol exposure and the role of genetics in determining vulnerability to alcohol-induced brain injury.

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Spotlight on Automatic-voluntary dissociation

Automatic-voluntary dissociation is the differential completion of an action depending on the patient’s attention to the task. Activities can be performed either attentively (“voluntarily”) or inattentively (“automatically”). Thus, 2 kinds of automatic-voluntary dissociation can occur. The kind that is more often described refers to the patient’s inability to complete an action voluntarily (attentively), but ability to do so automatically (inattentively). Less often described is the dissociation whereby activities are completed voluntarily, but not automatically, although this kind of dissociation is actually common. Recognizing automatic-voluntary dissociation in a patient may suggest potential methods for therapy for the concerned impairment, some of which have been developed.

In this article, Dr. Victor Mark of the University of Alabama at Birmingham reviews the many different manifestations of this phenomenon and discusses its implications for patient management.

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Spotlight on Corticobasal degeneration

Corticobasal degeneration is one of the atypical parkinsonian syndromes or Parkinsonism-plus syndromes that can mimic Parkinson disease, but it is distinct because of the added features of apraxia, dysphasia, cortical sensory signs, unusual dystonic postures, involuntary movements such as myoclonus, and “alien limb” sign.

In this article, Dr. Abhishek Lenka of MedStar Georgetown University Hospital reviews the clinical features of the disease as well as the pathological findings. New potential genetic etiologies of the disease are presented. Although treatment remains symptomatic, accurate diagnosis can help prepare families and help clinicians better understand and treat this progressive, fatal disorder.

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Spotlight on Migrainous infarction

Migrainous infarction is a rare complication after usual attacks of migraine with aura with a documentation of neuroimaging findings, such as cortical laminar necrosis. Migrainous infarction mostly occurs in the posterior circulation and in younger women with a history of migraine with aura. The majority of patients present with visual prolonged aura, and the stroke severity is mild with good short-term and long-term outcomes.

In this article, Dr. Shuu-Jiun Wang of the Brain Research Center, National Yang-Ming University, and the Neurological Institute, Taipei Veterans General Hospital updates the topic of migrainous infarction, including the diagnostic criteria proposed by the International Classification of Headache Disorders, 3rd edition, 2018. The summary also reports good outcomes of a Mexican study on a group of 15 patients with a mean follow-up of 7.5 years.

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Spotlight on Corticosteroid myopathies

Exposure to endogenous or exogenous corticosteroids may produce myopathy. A particularly interesting entity is severe myopathy occurring in critically ill patients exposed to high-dose corticosteroids and neuromuscular blocking agents.

In this updated article, Dr. Aziz Shaibani of Baylor College of Medicine and Dr. Husam Al Sultani of the Nerve and Muscle Center of Texas refer to the common problem of distinguishing steroid myopathy from an underlying inflammatory muscle disease. When glucocorticoids are tapered in this situation, the patient must be monitored for a flare of the underlying condition (in particular, rise of CK) and for signs of evolving adrenal insufficiency. Improved strength within 3 to 4 weeks after corticosteroid tapering is a good indicator that the weakness was indeed due to the drug and not to the underlying inflammatory muscle disease.

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Spotlight on Thyrotoxicosis

In this article, Dr. Douglas Ross of Harvard Medical School summarizes the clinical manifestations, causes, and treatment of thyrotoxicosis. Graves disease, toxic adenoma and toxic nodular goiter, and painless thyroiditis are the principal causes of thyrotoxicosis. Neurologists may encounter undiagnosed patients who present with a cerebrovascular accident due to atrial fibrillation complicating thyrotoxicosis, or they may see patients whose primary complaint is proximal muscle weakness or tremor. Subclinical hyperthyroidism has been associated with both subtle cognitive impairment and improvement in measures of mental health and mood. Initial evaluation and subsequent treatment of thyrotoxic patients is reviewed.

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Spotlight on Delayed sleep-wake phase disorder

In this article, Dr. Dr. Bradley Vaughn of UNC Hospital Chapel Hill and University of North Carolina School of Medicine and Dr. Sujay Kansagra of Duke University Delayed discuss sleep-wake phase disorder. The disorder is characterized by late bedtime and wake times, is frequently observed in adolescents and young adults, and is characterized by an inherent delay of biological rhythms compared to the natural daylight. This pattern may cause chronic sleep deprivation and lead to compromise in school and work performance. Some investigators have considered delayed sleep-wake phase disorder a marker for psychiatric and possibly neurologic issues.

Delayed sleep-wake phase disorder may disguise itself as insomnia, attention deficit disorder, emotional or affective disorder, or maladjustment, and it can be somewhat similar to the schedule seen in restless legs syndrome. The delay in the body clock can be treated with a combination of lifestyle modifications, appropriate timed exposure to light, and melatonin.

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