Page 195 - Read Online

Case Report

Gamma‑aminobutyric‑acid‑B receptor

antibodies in limbic encephalitis with small cell

lung cancer

Ke‑Qin Liu, Sheng‑Qiang Yan, Min Lou
Department of Neurology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou 310009, Zhejiang, China.

ABSTRA CT

Encephalitis associated with antibodies to gamma‑aminobutyric‑acid B (GABA‑B) is a subgroup of autoimmune synaptic encephalitis
with typical features of limbic encephalitis and small cell lung cancer (SCLC). We report a case of anti‑GABA‑B receptor encephalitis
in a 57‑year‑old man who presented with seizures, memory loss, and abnormal behavior. He developed partially neurological
responses to immunotherapy, but refused comprehensive tumor screening. The symptoms were aggravated again 4 months later.
Workup showed antibodies to GABA‑B receptors and tumor screening revealed SCLC. It highlights the importance of early screening
of underlying tumor and anti‑tumor treatment in paraneoplastic cases.

Key words: Gamma‑aminobutyric‑acid‑B receptor antibodies, limbic encephalitis, small cell lung cancer

INTRODUCTION with typical symptoms of LE and was finally found
SCLC 5 months after onset.
Encephalitis associated with antibodies to
gamma-aminobutyric-acid B (GABA-B) receptors has CASE REPORT
been recognized as a subgroup of autoimmune synaptic
encephalitis recently. It has been demonstrated that A 57-year-old man was admitted to our hospital with
[1]
GABA-B receptors were engaged during rhythmic recurrent generalized tonic-clonic seizure (GTCS),
activity in the hippocampus and sculpted this activity. which is also called grand mal seizure, for 4 months and
[2]
Correspondingly, anti-GABA-B encephalitis mostly aggressive behavior, memory impairment, confusion
presents with symptoms of limbic encephalitis (LE), for 4 days. Subsequent neurological examination
which was characterized by memory loss, confusion, revealed disorientation, lack of concentration and
hallucinations, personality changes, and seizures. The loss of memory, predominantly short-term memory.
GABA-B receptors are also distributed in the cerebral Past medical history was clean.
cortex, thalamic nuclei, cerebellum, and amygdala.
[3]
The initial symptom presentation of cerebellum or Blood cell count, general chemistry, thyroid function and
brain stem were thus reported in some patients, such tumor markers, including carcinoembryonic antigen,
as rotational vertigo, ataxia, and opsoclonus. [4,5] a-fetoprotein, carbohydrate antigen-199 (CA199),
CA125, CA242, cytokeratin-211 and neuron-specific
In nearly half of patients with anti-GABA-B encephalitis, enolase (NSE), were unrevealing. Cerebrospinal
the immune response occurs as a paraneoplastic event, fluid (CSF) analysis (on day 3) detected an
most of which were small cell lung cancer (SCLC). Here, elevation of protein, count of white blood cells and
we report a case of a 57-year-old man who presented glucose levels [Table 1]. Brain magnetic resonance
imaging (MRI) revealed bilateral increased T2 signal in
Access this article online
the medial temporal lobe [Figure 1]. Chest computed
Quick Response Code: tomography (CT) revealed enlarged mediastinal lymph
Website:
www.nnjournal.net nodes.

DOI: The seizure was controlled after the administration of
10.4103/2347-8659.159077 valproic acid (500 mg/day) and immunomodulating
therapy with 40 mg of methylprednisolone on

Corresponding Author: Prof. Min Lou, Department of Neurology, School of Medicine, The Second Affiliated Hospital of
Zhejiang University, No. 88, Jiefang Road, Hangzhou 310009, Zhejiang, China. E‑mail: loumingxc@vip.sina.com

PB Neuroimmunol Neuroinflammation | Volume 2 | Issue 3 | July 15, 2015 Neuroimmunol Neuroinflammation | Volume 2 | Issue 3 | July 15, 2015 187