Neuro-Infectious Disease

A major area of Dr. Funk's neuro-infectious practice is the diagnosis and treatment of vestibular neuritis and other infectious or post-infectious vestibular disorders. Vestibular neuritis can produce acute unilateral vestibular dysfunction following inflammation of the vestibular nerve, commonly in association with a presumed viral or post-viral mechanism. Dr. Funk uses detailed bedside vestibular and neurological examination together with video-guided infrared oculography when appropriate to objectively analyze spontaneous and gaze-evoked nystagmus, ocular fixation, vestibulo-ocular function, and other eye-movement findings. These findings help determine whether a vestibular syndrome localizes to the peripheral vestibular system or suggests central neurological pathology requiring further investigation.

Infection can also produce peripheral and central neurological disease through several distinct mechanisms. Lyme neuroborreliosis, varicella-zoster virus, HIV, hepatitis viruses, and other infections can involve peripheral nerves, nerve roots, cranial nerves, or other components of the nervous system, while infection can also trigger immune-mediated neuropathies such as Guillain-Barré syndrome. Dr. Funk also diagnoses Ramsay Hunt syndrome (herpes zoster oticus), in which reactivation of varicella-zoster virus can produce facial nerve palsy and, when the vestibulocochlear system is involved, vertigo, hearing abnormalities, and other vestibular or auditory dysfunction.

Gastrointestinal and systemic infections can also have important neurological consequences. Enteric infections can trigger post-infectious neurological disease, while invasive bacterial infections can, under appropriate circumstances, disseminate systemically and involve the central nervous system. Certain pathogenic strains of Escherichia coli (E. coli), for example, can cause severe systemic disease with neurological complications, while specific E. coli strains are recognized causes of meningitis. Dr. Funk therefore considers whether neuropathy or other neurological dysfunction reflects direct infection, systemic consequences of infection, post-infectious immune activation, or another neurological mechanism rather than assuming that an infection originating outside the nervous system cannot be neurologically relevant.

Dr. Funk also performs advanced laboratory investigation when an infectious or post-infectious etiology is suspected. Depending on the clinical presentation and differential diagnosis, testing may investigate Lyme disease and Borrelia infection, other tick-borne pathogens and coinfections, COVID-19, EBV, CMV, herpesviruses, infectious exposure and immune responses, inflammatory abnormalities, and other biological mechanisms potentially contributing to neurological dysfunction. An important part of this process is distinguishing active infection, previous infectious exposure, post-infectious neurological dysfunction, secondary neuroimmune activation, and unrelated neurological disease rather than automatically attributing persistent neurological symptoms to an infection.

A polysubspecialty approach is particularly important because infection-associated neurological disease frequently crosses traditional neurological boundaries. Dr. Funk integrates Neuro-Infectious Disease with Neuroimmunology, Neuromuscular Medicine and Peripheral Neuropathy, Vestibular Neurology, Dysautonomia/POTS, Neuro-Ophthalmology, Neuroimaging, Cognitive and Memory Disorders, Headache and Pain Medicine, and other relevant neurological subspecialties to determine how infectious, immune, autonomic, peripheral, vestibular, and central neurological mechanisms interact within the individual patient.

Treatment follows the diagnosis, localization, and underlying mechanism. Dr. Funk develops individualized treatment strategies addressing infectious, post-infectious, neuroimmune, inflammatory, metabolic, autonomic, and neurological mechanisms contributing to the patient's condition. When prescription antiviral, antimicrobial, or other pharmacological therapy is appropriate, Dr. Funk may recommend medication strategies and co-manage the neurological aspects of treatment with infectious disease physicians, primary care physicians, or other prescribing providers. He may also prescribe individualized over-the-counter medications and nutraceutical strategies intended to support antimicrobial and antiviral function, immune regulation, inflammatory control, and neurological recovery in conjunction with appropriate prescription therapies and neurological treatment.

When infectious or post-infectious disease has produced persistent neurological dysfunction, Dr. Funk develops individualized neurological rehabilitation and neuromodulation based on the structures, pathways, and neural networks affected. Depending on the neurological localization, treatment may incorporate vestibular and oculomotor rehabilitation, neuro-optometric rehabilitation, motor and sensory rehabilitation, peripheral nerve stimulation, transcutaneous auricular vagus nerve stimulation (taVNS), transcranial photobiomodulation, balance and coordination rehabilitation, nutraceutical and over-the-counter strategies, and other targeted interventions when clinically appropriate.

The objective is not simply to identify that a patient has been exposed to an infectious organism. Dr. Funk determines whether an infectious or post-infectious process is neurologically relevant, diagnoses the resulting neurological disorder, localizes the affected nervous-system structures, pathways, and networks, investigates interacting infectious, immune, inflammatory, and physiological mechanisms, and develops an individualized strategy to address the neurological dysfunction that remains.