Differential Diagnosis
- Single most likely diagnosis
- NMDA receptor encephalitis: This condition is characterized by the presence of antibodies against the N-methyl-D-aspartate (NMDA) receptor, a neuronal cell surface receptor. The patient's symptoms, including behavioral changes, abnormal movements (orofacial dyskinesias), limb stiffness, short-term memory loss, disorientation, and involuntary limb movements, are consistent with NMDA receptor encephalitis. The CSF analysis showing lymphocytic pleocytosis further supports this diagnosis.
- Other Likely diagnoses
- Anti-LGI1 encephalitis: This is another form of autoimmune encephalitis that can present with similar symptoms, including behavioral changes, memory loss, and abnormal movements. The presence of antibodies against a neuronal cell surface receptor could also be consistent with this diagnosis.
- Hashimoto's encephalitis: This condition is associated with autoimmune thyroiditis and can present with a range of neurological symptoms, including behavioral changes, memory loss, and abnormal movements. While less likely, it should be considered in the differential diagnosis.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Viral encephalitis (e.g., herpes simplex encephalitis): Although the presence of antibodies against a neuronal cell surface receptor suggests an autoimmune etiology, viral encephalitis can present with similar symptoms and is a medical emergency that requires prompt treatment.
- Subacute sclerosing panencephalitis (SSPE): This rare but deadly condition is caused by a persistent measles virus infection and can present with behavioral changes, memory loss, and abnormal movements.
- Rare diagnoses
- Bickerstaff's brainstem encephalitis: This rare condition is characterized by inflammation of the brainstem and can present with a range of neurological symptoms, including behavioral changes, memory loss, and abnormal movements.
- Paraneoplastic encephalitis: This condition is associated with underlying malignancy and can present with a range of neurological symptoms, including behavioral changes, memory loss, and abnormal movements. While rare, it should be considered in the differential diagnosis, especially if other symptoms or signs suggest an underlying cancer.