Neuroleptic Malignant Syndrome: A Case of Unknown Causation and Unique Clinical Course

Abstract

Neuroleptic malignant syndrome (NMS) is a rare, potentially lethal syndrome known to be related to the initiation of dopamine antagonist medications or rapid withdrawal of dopaminergic medications. It is a diagnosis of exclusion with a known sequela of symptoms, but not all patients experience these characteristic symptoms making it difficult at times to diagnose and treat. Herein, we present a unique case of NMS with unclear etiology and a unique clinical course. Our case report also raises the question of whether or not adjusting doses of previously prescribed neuroleptic medications can provoke NMS, providing valuable information for providers treating these complex patients.

Valbenazine, Fluphenazine, and Possible Neuroleptic Malignant Syndrome in a 58-Year-Old Woman

“…Until further data are available, prescribers should educate their patients and monitor closely for signs and symptoms of serious adverse effects, including NMS. This case and the cases referenced 2,3 of NMS involving valbenazine also have high-potency antipsychotics present; there is perhaps need for provider caution and patient education regarding the interaction between valbenazine and high-potency antipsychotic leading to increased NMS risk.…”

“…2 There has also been another case reporting NMS in a patient with likely haloperidol-induced TD with treatment via valbenazine. 3 There have been numerous case studies exploring the relationship between an older VMAT-2 inhibitor, tetrabenazine, and NMS, which has been theorized to be associated via its innate ability inhibiting vesicular dopamine uptake in addition to a mild dopamine receptor antagonistic property. 5 However, valbenazine lacks any appreciable binding affinity for dopaminergic receptors.…”

“…To our knowledge, there has been one other case of NMS noting similar relationship concerning aripiprazole-induced TD with treatment by valbenazine 2 . There has also been another case reporting NMS in a patient with likely haloperidol-induced TD with treatment via valbenazine 3 . There have been numerous case studies exploring the relationship between an older VMAT-2 inhibitor, tetrabenazine, and NMS, which has been theorized to be associated via its innate ability inhibiting vesicular dopamine uptake in addition to a mild dopamine receptor antagonistic property 5 .…”

“…1 Although only formally approved for treatment-resistant childhood epilepsies, there is a growing interest in the use of CBD to treat neurodevelopmental and neuropsychiatric disorders such as anxiety, autism spectrum disorder (ASD), and attention deficit/hyperactivity disorder. 2,3 Here, CBD was added to the treatment regimen of 2 patients with neurodevelopmental disorders with drastically different therapeutic outcomes. Symptoms in one patient improved with no adverse events, whereas the other patient exhibited severe adverse events.…”

“…There have been multiple cases reported of NMS with patients treated with VMAT-2 inhibitors, but few reported with newer VMAT-2 inhibitors. In our literature review, we found only 2 case reports 2,3 of NMS involving a newer VMAT-2 inhibitor. We wish to report a case of possible NMS in a patient on valbenazine treatment.…”