Autoimmune encephalopathy presenting as a ‘posterior circulation stroke’

Meningioma preceding CASPR2 antibody limbic encephalitis with a stroke mimic: A case report

RATIONALE

Todd paralysis (a stroke-like presentation in some patients with epilepsy) caused by limbic encephalitis (LE) is not easily distinguished from acute ischemic stroke by clinicians in the emergency room.

PATIENT CONCERNS

We report a contactin-associated protein-like 2-antibody (CASPR2-Ab)-positive patient who presented with atypical LE.

DIAGNOSES

CASPR2-Ab-positive LE was the presumed diagnosis. Re-evaluation of cerebrospinal fluid (CSF) samples revealed autoantibodies targeting CASPR2 at an immunoglobulin G titer of 1:1. The clinical presentation of subacute onset seizures, abnormal electroencephalography, hypermetabolism on positron emission tomography, good immunotherapy response, and the presence of specific antibodies in serum supports a diagnosis of autoimmune LE.

INTERVENTION

The patient received glucocorticoids (1 g for 3 days and 500 mg for 3 days), immunoglobulin (25 g for 3 days), sodium valproate (1 g for 3 days), and clonazepam (1 mg for 3 days).

OUTCOMES

Remission of temporal lobe epilepsy symptoms and cognitive dysfunction was observed. Follow-up analysis of CSF and serological examination were not approved by the patient. His Mini-Mental State Examination score improved to 21/30. Stable remission of symptoms was achieved throughout the follow-up period of 50 days.

LESSONS

Autoimmune encephalitis (AE) should be considered in cases of late-onset epilepsy following meningioma peritumoral brain edema and resection. A diagnosis of AE should be considered in patients presenting with stroke-like symptoms if the magnetic resonance imaging abnormality does not match a known vascular territory. Early and correct diagnosis is crucial because immunotherapy is usually effective for this disease.

Stroke preceding autoimmune encephalitis with neuronal potassium channel antibody

Autoimmune encephalitis related to voltage-gated potassium channel (VGKC) antibodies can occur as a complication of cancer but, more frequently, as a non-paraneoplastic disorder. The prompt recognition and treatment could mitigate the morbidity associated with this entity, but the broad-spectrum of neurological manifestations often makes the diagnosis a challenge. The authors describe, here, a unique case of autoimmune encephalitis related to VGKC antibodies preceded by an ischaemic stroke. Conditions associated with the stroke (infection, seizures, metabolic disturbances) had delayed the diagnosis. The authors suggest that autoimmune encephalitis needs to be taken into consideration as part of a differential diagnosis in patients with prolonged encephalopathy following an ischaemic stroke. Infection may trigger an inflammatory response. In addition, the rupture of blood brain barrier that occurs in stroke may have a pathogenic role by allowing antibodies to gain access to the central nervous system.