In the absence of the adverse effect of a medication, orthostasis is uncommon in a well-hydrated young person. Some guidelines4 suggest that symptoms of catatonia should be considered a red flag for autoimmune encephalitis. According to the Bush-Francis Catatonia Rating Scale, commonly identified features include immobility, staring, mutism, posturing, withdrawal, rigidity, and gegenhalten.15 Catatonia is common among patients with anti-NDMA receptor encephalitis, though it may not be initially present and could emerge later.2 However, there are documented cases of autoimmune encephalitis where the patient had only isolated features of catatonia, such as echolalia or mutism.2
CASE CONTINUED
History helps narrow the diagnosis
Ms. L’s parents say their daughter has not had prior contact with a therapist or psychiatrist, previous psychiatric diagnoses, hospitalizations, suicide attempts, self-injury, or binging or purging behaviors. Ms. L’s paternal grandfather was diagnosed with schizophrenia, but he is currently employed, lives alone, and has not taken medication for many years. Her mother has hypothyroidism. Ms. L was born at full term via vaginal delivery without cardiac defects or a neonatal intensive care unit stay. Her mother said she did not have postpartum depression or anxiety, a complicated pregnancy, or exposure to tobacco, alcohol, or illicit drug use. Ms. L has no history of childhood seizures or head injury with loss of consciousness. She is an only child, born and raised in a house in a metropolitan area, walked at 13 months, did not require early intervention or speech therapy, and met normal language milestones.
She attended kindergarten at age 6 and progressed throughout public school without regressions in reading, writing, or behavioral manifestations, and did not require a 504 Plan or individualized education program. Ms. L graduated high school in the top 30% of her class, was socially active, and attended a local college. In college, she achieved honor roll, enrolled in a sorority, and was a part of a research lab. Her only medication is oral contraception. She consumes alcohol socially, and reports no cannabis, cigarette, or vaping use. Ms. L says she does not use hallucinogens, stimulants, opiates, or cocaine, and her roommate and family confirm this. She denies recent travel and is sexually active. Ms. L’s urinary and serum toxicology are unremarkable, human chorionic gonadotropin is undetectable, and her sodium level is 133 mEq/L. A measure of serum neutrophils is 6.8 x 109/L and serum lymphocytes is 1.7 x 109/L. Her parents adamantly request a Neurology consultation and further workup, including a lumbar puncture (LP), EEG, and brain imaging (MRI).
This information is useful in ruling out other potential causes of psychosis, such as substance-induced psychosis and neurodevelopmental disorders that can present with psychosis. Additionally, neurodevelopmental abnormalities and psychiatric prodromal symptoms are known precedents in individuals who develop a primary psychotic disorder such as schizophrenia.16 A family history that includes a psychotic illness may increase the likelihood of a primary psychotic disorder in offspring; however, clinicians must also consider the accuracy of diagnosis in the family, as this can often be inaccurate or influenced by historical cultural bias. We recommend further elucidating the likelihood of a genetic predisposition to a primary psychotic disorder by clarifying familial medication history and functionality.
For example, the fact that Ms. L’s grandfather has not taken medication for many years and has a high degree of functioning and/or absence of cognitive deficits would lower our suspicion for an accurate diagnosis of schizophrenia (given the typical cognitive decline with untreated illness). Another piece of family history relevant to autoimmune encephalitis includes the propensity for autoimmune disorders, but expert opinion on this matter is mixed.17 Ms. L’s mother has hypothyroidism, which is commonly caused by a prior episode of Hashimoto’s autoimmune thyroiditis. Some physicians advocate for measuring antithyroid antibodies and erythrocyte sedimentation rate or C-reactive protein to gauge the level of autoimmunity, but the usefulness of these measures for detecting autoimmune encephalitis is unclear. These serum markers can be useful in detecting additional important etiologies such as systemic infection or systemic inflammation, and there are conditions such as steroid-responsive encephalopathy with associated thyroiditis, which, as the name suggests, responds to steroids rather than other psychotropic medications. Other risk factors for autoimmune encephalitis include being female, being young, having viral infections (eg, HSV), prior tumor burden, and being in the postpartum period.18 Some experts also suggest the presence of neurologic symptoms 4 weeks after the first psychiatric or cognitive symptom presentation increases the likelihood of anti-NMDA receptor encephalitis, and a lack of neurologic symptoms would make this diagnosis less likely.6,19
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