Intracranial hepatitis B virus (HBV) infection following intracerebral hemorrhage in a patient with seronegative occult HBV infection.

Hepatitis B virus (HBV) infection is primarily associated with liver diseases but can also manifest with various extrahepatic complications. While numerous extrahepatic manifestations have been reported in acute or chronic hepatitis B patients, intracranial HBV infection remains clinically rare. A 43-year-old male had a pre-existing diagnosis of serologically negative occult HBV infection (OBI), which was initially diagnosed by detecting HBV DNA in serum while HBsAg, anti-HBs, anti-HBe, and anti-HBc were all negative. Following intracerebral hemorrhage, the patient's consciousness gradually restored through a course of rehabilitation therapy. Subsequently, the patient developed persistent fever and his level of consciousness progressively deteriorated. Serological testing confirmed the presence of HBsAg and HBeAg, the HBV loads in the serum was high, subsequent metagenomic next-generation sequencing (mNGS) of the cerebrospinal fluid (CSF) revealed positivity for HBV. After 8 weeks of treatment with entecavir, the HBV loads in the serum and CSF decreased significantly, the patient's consciousness improved, and the patient's temperature returned to normal. This study first reported a seronegative OBI patient developing intracranial HBV infection following intracerebral hemorrhage and clarified the diagnostic value of mNGS in rare intracranial infections.