Lyme Meningitis Linked to Low Sodium and SIADH

Lyme meningitis may present with neurologic and electrolyte abnormalities.
An elderly woman developed persistent hyponatremia and back pain.
Her spinal tap ultimately confirmed Lyme meningitis.

There are many causes of hyponatremia, including infections involving the central nervous system.

Only a small number of reports have described Lyme meningitis presenting with hyponatremia and Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH), according to the authors.

Hyponatremia occurs when blood sodium levels become abnormally low, often because the body retains too much water. Symptoms may include confusion, fatigue, poor concentration, weakness, or unsteadiness.

Back Pain and Cognitive Symptoms Preceded Lyme Meningitis Diagnosis

One month before hospitalization, the 83-year-old woman presented to the emergency department with stabbing back pain localized to the left shoulder.

“The shoulder pain gradually subsided but lower back pain ensued, worsening at night,” wrote the authors. “In parallel, she noticed difficulties in concentrating, unsteadiness, and poor appetite.”

The patient was admitted for evaluation of gastrointestinal complaints, weight loss, and persistent hyponatremia.

Her sodium level was low at 125 mmol/L, consistent with SIADH.

Persistent Hyponatremia and Lyme Meningitis Evaluation

Initially, clinicians suspected medication-related hyponatremia because no clear cause could be identified.

Her antihypertensive medication was changed, and sodium levels improved only slightly.

However, one month later, her sodium level remained low at 126 mmol/L.

“In view of the history, nocturnal back pain and obscure hyponatremia, she was admitted for a lumbar puncture,” the authors explained.

Her spinal tap was diagnostic for Lyme meningitis.

SIADH Resolved After Lyme Disease Treatment

The patient completed a 3-week course of antibiotics, after which the SIADH resolved.

“In hindsight, the lancinating shoulder pain prompting the patient’s first hospital visit likely represented Bannwarth syndrome, a radiculoneuritis occurring early in the course of Lyme disease,” the authors pointed out.

Bannwarth syndrome is a neurologic manifestation of Lyme neuroborreliosis that may involve severe radiating pain, meningitis, sensory symptoms, weakness, or autonomic dysfunction.

For additional discussion, see meningitis and radiculitis due to Lyme disease.

FAQ: Lyme Meningitis and SIADH

Can Lyme meningitis cause hyponatremia?

Yes. Although uncommon, Lyme meningitis and Lyme neuroborreliosis have been associated with SIADH and low sodium levels in published case reports.

What symptoms can occur with Lyme meningitis?

Symptoms may include headache, neck pain, cognitive problems, back pain, radiculitis, weakness, gait instability, or other neurologic complaints.

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention