Table 1. Alternative Final Diagnoses in Those Initially Misdiagnosed as Autoimmune Encephalitis.
| Alternative diagnosis | No. (%) | |
|---|---|---|
| Individuals with initial diagnosis (n = 107) | Individuals who fulfilled possible autoimmune encephalitis criteria (n = 30) | |
| Functional neurologic disorder | 27 (25) | 6 (22) |
| Neurodegenerative dementia | 22 (20.5) | 5 (23) |
| Alzheimer diseasea | 6 | 0 |
| Dementia with Lewy bodiesb | 4 | 1 |
| Behavioral variant frontotemporal dementia | 4 | 2 |
| Creutzfeldt-Jakob disease | 2 | 1 |
| Vascular cognitive impairment | 1 | 0 |
| Otherc | 5 | 1c |
| Psychiatric disease | 19 (18) | 2 (11) |
| Depressiond | 7 | 2 |
| Anxiety | 3 | 0 |
| Schizophrenia | 2 | 0 |
| Bipolar | 2 | 0 |
| Othere | 5 | 0 |
| Nonspecific cognitive syndrome in the setting of ≥1 of fibromyalgia, chronic fatigue, sleep disorder, medication adverse reaction, or other comorbidityf | 11 (10) | 1 (9)f |
| Neoplasm | 10 (9.5) | 7 (70) |
| Glioma (glioblastoma, astrocytoma, or not otherwise specified)g | 7 | 5 |
| Primary central nervous system lymphoma | 2 | 2 |
| Cerebellar medulloblastoma with cerebellar cognitive syndrome | 1 | 0 |
| Seizure disorder, nonimmune-mediatedh | 5 (4.5) | 3 (60) |
| Infectious | 3 (2.5) | 1 (33) |
| Residua of prior viral encephalitis | 2 | 1 |
| HIV leukoencephalopathy | 1 | 0 |
| Mitochondrial encephalomyopathy lactic acidosis and strokelike episodes | 2 (2) | 1 (50) |
| Other metabolic | 2 (2) | 1 (50) |
| Adrenal insufficiency | 1 | 0 |
| Wernicke encephalopathy | 1 | 1 |
| Other | 6 (6) | 3 (50) |
| Small vessel vasculitis | 2 | 0 |
| Klein Levin syndrome | 1 | 0 |
| Nonimmunotherapy responsive progressive cerebellar degeneration with cerebellar cognitive syndrome | 1 | 1 |
| Multiple sclerosis and depression | 1 | 1 |
| Nonimmune encephalopathy without further classification | 1 | 1 |
One individual had coexisting vascular cognitive impairment; 1 patient with prior typical anti-LGI1 encephalitis developed an insidious dementia in follow-up that was suspected to be recurrent autoimmune encephalitis, but repeat LGI1 antibodies testing results were negative (and thus we categorized as antibody negative for this study), and the patient did not respond to immunotherapy and autopsy later confirmed Alzheimer disease as the cause of the insidious dementia.
Two individuals were suspected to have comorbid Alzheimer disease.
Progressive supranuclear palsy, 1; neuronal intranuclear inclusion disease, 1 (this patient fulfilled criteria for possible autoimmune encephalitis); primary lateral sclerosis with cognitive impairment, 1; amnestic mild cognitive impairment, 1; neurodegenerative unclassifiable, 1.
Two individuals had psychosis, one of which also had catatonia.
Depression and anxiety in combination, 1; developmental delay with regression, 1; psychiatric disease without classification, 3.
Other contributors included migraine headaches, insomnia, and psychiatric comorbidity; in this category, there were often multiple combinations of these factors contributing.
In 1 patient, biopsy confirmation was not available.
One from multiple cavernous malformations.