Anti-N-methyl-d-aspartate Receptor Encephalitis Related Sinus Node Dysfunction and the Lock-Step Phenomenon

Abstract

Described in 2007, anti-N-methyl-d-aspartate receptor encephalitis (ANMDARE) is a rare autoimmune limbic encephalitis affecting young adults (predominantly women of reproductive age) and is a paraneoplastic manifestation of ovarian teratoma in about half of the cases. ANMDARE is characterized by psychiatric changes, neurological changes, autonomic instability and cardiac dysrhythmias. In this report, we present a 36-year-old woman who was 16 weeks pregnant and brought to the hospital with confusion and subsequently had a seizure with Electroencephalography (EEG) demonstrated an extreme delta brush pattern consistent with ANMDARE. Patient developed sinus nodal dysfunction and was also found to have ovarian teratoma, a rather typical presentation for ANMDARE, that is considered a paraneoplastic syndrome for ovarian teratoma. In this report, we highlight the cardiac manifestation of ANMDARE, the pathophysiology associated with autonomic instability, and management strategies of this rare, and largely devastating illness.

Keywords: Lock Step Phenomenon; anti-N-methyl-d-aspartate receptor encephalitis (ANMDARE); autoimmune encephalitis; autonomic dysregulation; ovarian teratoma; sinus node dysfunction.

Figure 1.

Sinus Tachycardia 110 bpm (Admission EKG)

Figure 2A.

Sinus Tachycardia at 116 bpm

Figure 2B.

Sinus Pause of approximately 7 seconds followed by sinus bradycardia at a rate of 30 bpm

Figure 3.

Red arrow showing successful placement of transvenous pacemaker tip

Figure 4.

Pelvic MRI demonstrating intrauterine gestation and a left ovarian complex mass with layering debris approximately 33mm × 32mm in size