Abstract 323: Lyme Neuroborreliosis Presenting with CNS Vasculitis, Subarachnoid Hemorrhage, and Rupture of a PICA Aneurysm: A Case Report
Authors: Arthur M. , Penn D. , Wright P. , Lebovitz J. 
Published: January 2025

Background
Lyme disease, caused by Borrelia burgdorferi, is a tick‐borne illness that commonly manifests as lymphocytic meningitis, cranial neuritis, and radiculoneuritis. Central nervous system (CNS) vasculitis is an exceedingly rare complication of Lyme neuroborreliosis (LNB), often presenting with stroke or transient ischemic attack, and less frequently with cerebral venous sinus thrombosis, intracerebral hemorrhage, or aneurysm. To date, the literature includes only one report of LNB‐associated CNS vasculitis presenting with subarachnoid hemorrhage (SAH) and rupture of a basilar aneurysm.

Objective:
We report an exceptionally rare case of LNB‐associated CNS vasculitis manifesting as SAH and a dysplastic posterior inferior cerebellar artery (PICA) aneurysm.

Methods
A 67‐year‐old male with a history of seizure disorder, migraine, and hypertension presented with the worst headache of his life. He subsequently experienced neurological decline, requiring intubation for airway protection. CT imaging revealed diffuse intraventricular hemorrhage with hydrocephalus involving the 3rd and 4th ventricles, along with SAH in the bilateral sylvian and interhemispheric fissures. The patient's Hunt and Hess grade was 4, and the Modified Fisher score was 4. An emergent external ventricular drain (EVD) was placed. A diagnostic cerebral angiogram (DSA) showed a severely dysplastic PICA with multiple areas of ectasia and a 3.5 times 1.5 mm saccular aneurysm, which was successfully treated with endovascular coiling. The hospital course was complicated by aspiration pneumonia and a urinary tract infection, managed with ceftriaxone. The patient also experienced recurrent high‐grade fevers, suspected to be of central origin, although cerebrospinal fluid (CSF) analysis was negative for infection. One month into hospitalization, neurological examination revealed bilateral ataxia, gait instability, and mild dysphasia. Follow‐up CTA demonstrated no residual flow in the left PICA aneurysm, and CT imaging showed resolution of the SAH. During rehabilitation, the patient's ataxia and gait instability worsened, and he developed horizontal nystagmus and diplopia. Additionally, a patchy red rash developed, which responded to dupilumab. A repeat DSA at 6 months revealed bilateral posterior cerebral artery (PCA) beading and stenosis with ectatic segments and reduced flow, consistent with PCA vasculitis. Further investigation disclosed a history of Lyme disease 8 years prior, characterized by fever, headache, and chills, and treated with doxycycline. Repeat CSF analysis showed a protein level of 74 mg/dL, a CSF Lyme index of 1.4, and the presence of 4 IgG bands. Initial CSF negativity was attributed to the partial course of ceftriaxone administered in hospital. The patient was ultimately diagnosed with LNB and treated with a 28‐day course of 2 g ceftriaxone. Infectious and rheumatologic workups were otherwise negative.

Conclusion
In cases of non‐traumatic SAH associated with CNS vasculitis or aneurysm, where infection and other secondary causes are considered, Lyme neuroborreliosis should also be evaluated as a potential underlying condition, especially in patients with a clinical history suggestive of prior Lyme disease.