Infections of the Nervous System: Current Approaches

A vast array of infectious pathogens can affect the nervous system, leading to symptoms at any level of the neurologic axis. Given the complexity in diagnosis and treatment of neuroinfectious diseases, it is essential that neurologists remain familiar with advances in diagnostic testing, emergence of novel pathogens, and current treatment guidelines. I am thrilled to introduce the articles in this issue, which take a cutting-edge global approach to a wide variety of neurologic infections.

To open the issue, Drs. Vishnevetsky, Wilcox, Farhad, Varma-Doyle, O’Neal, and Robbins provide a comprehensive and timely overview of the long-term neurologic complications of COVID-19. Many of the symptoms associated with post-acute sequelae of COVID-19 (PASC) are neurologic in nature, including cognitive dysfunction, sensory changes, and autonomic symptoms. The authors describe a practical clinical approach to these symptoms while placing them in the context of syndromes commonly encountered by neurologists such as myalgic encephalomyelitis and postural orthostatic tachycardia syndrome.

Next, Drs. Kolchinski and Venkatesan explore viral infections of the central nervous system by focusing on updates in our understanding of 3 specific viruses. The authors provide a clinical update on the increasingly recognized phenomenon of post-herpes simplex virus autoimmune encephalitis, review changes in varicella zoster virus diagnostic testing and epidemiology, and describe the newly recognized entity of enterovirus D68-mediated acute flaccid myelitis.

Dr. Harrold then provides a detailed discussion of the neurologic manifestations of tick-borne illnesses, reviewing the most common neurologic manifestations of Lyme disease including cranial neuritis, radiculitis, and meningitis, and reviewing guidelines for appropriate diagnostic testing and treatment of Lyme disease. Additional tick-borne illnesses with neurologic sequelae discussed in this article include Powassan, Anaplasmosis, Ehrlichiosis, Rocky Mountain Spotted Fever, Tularemia, and Babesiosis.

Drs. Marshall and Abdel-Wahed focus on the neurologic complications of syphilis, tuberculosis, and cysticercosis which are highly prevalent worldwide, especially in vulnerable populations. Given the potential for high morbidity and mortality, early recognition of these infections is essential for practicing neurologists. In this article, the authors review the most common neurologic clinical presentations, sensitivity and specificity of widely available diagnostic tests, and guideline-based treatment strategies for these infections.

Over 39 million people are living with HIV worldwide, and despite advances in modern antiretroviral therapy, many may still experience neurologic sequelae. Dr. Ocampo reviews the pathophysiology of HIV entry into the central nervous system (CNS) and the contribution of the CNS reservoir to the development of cognitive impairment, HIV CNS escape, and cerebrovascular diseases. The article also provides an overview of the neurologic complications of acute HIV infection, including the most common peripheral neurologic complication of HIV, peripheral neuropathy.

Finally, Drs. Ji and Zunt contribute a unique article on the effects of climate change on the global landscape of neuroinfectious diseases. The authors discuss how rainfall and rising temperatures can alter the epidemiology of vector-borne infections, rising lake temperatures can lead to algae blooms, and human migration can lead to increased rates of sexually transmitted infections and highly contagious pathogens, all of which may have neurologic complications. Additionally, the authors review the effects of habitat destruction and population displacement on the emergence of new zoonotic infections such as Nipah virus encephalitis.

Thank you to the authors for their excellent contributions to this issue.