3.1 Clinical features of nine patients with multiple anti-neuronal antibodies
Nine AE patients (9/85, 10.6%) with co-existence of multiple anti-neuronal antibodies were identified from 85 AE patients hospitalized in our department between August 2019 and February 2022. The male:female ratio was 4:5. Age of onset ranged from 15 to 72 years (median 66 years). The clinical manifestations of the 9 patients were consistent with encephalitis symptoms (Table 1), clinically characterized by disturbance of consciousness, seizures, cognitive impairment, psychiatric disorder, and so on. Pulmonary malignant tumor was suspected in 2 patients. Seven patients received immunotherapy (glucocorticoids, intravenous immunoglobulin (IVIG), plasmapheresis, or mycophenolate mofetil); one patient was treated with acyclovir (1.5g/day) alone; and one patient refused any treatment. Collectively, 6 patients showed completely or partially neurological improvement after immunotherapy, one patient was complete recovery after
antiviral therapy alone, and 2 patients with suspected malignant tumors died during the follow-up.
Cerebral MRI revealed that 4 patients showed abnormal lesions, mainly distributing in the tempo-parie-occipital lobe, insular lobe, hippocampus, and basal ganglia. Electroencephalogram (EEG) was performed in 8 patients, including slow wave increase in 5 patients, mild abnormality in 2 patients, and epileptiform discharge in one patient. The panel of auto-antibody revealed that NMDAR antibody was positive in 6 patients (case 1–5, and 9), among which 3 patients had CASPR2 antibody, 2 patients had GABABR antibody, and one patient simultaneously had GABABR and GAD65 antibodies. One patient (case 6) had a co-existence of AMPAR2 and Hu antibodies. Two patients (case 7 and 8) had LGI1 antibody co-existing IGLON5 or CASPR2 antibody, respectively.
3.1.1 Patient 1
An adult (ranging 35–40 years old) woman was admitted for recurrent seizures over 20 years. The attacks occurred several times a year and lasted for 1–2 min. Other accompanying symptoms include sleep disorder and cognitive impairment. Cranial MRI revealed no abnormalities (Figure. 1A). EEG indicated epileptic discharge in the left middle temporal. Chest and abdomen CT and serum tumor markers were normal. Oxazepine and levetiracetam were administered for anticonvulsive therapy. After identification of positive NMDAR and CASPR2 antibodies, high-dose methylprednisolone (0.5g and 0.25g, 3 days for each dosage) were intravenously injected, followed by prednisone (60mg daily) for 4 weeks, and then gradually reduced the dose by 5mg every 2 weeks until the final withdrawal. Follow-up evaluation after 6 months revealed that the symptoms were significantly improved and free of seizures.
3.1.2 Patient 2
An old (ranging 56–60 years old) woman presented with insomnia, speech disorder, emotional liability, and confusion for 10 days. Cerebral MRI was normal (Figure. 1B). EEG had no abnormalities. CSF analysis showed the number of cells was 0/µl (reference 0–10/µl), the level of protein was 24mg/dL (reference 15-45mg/dL), and the glucose level was 3.5mmol/L (reference 2.5-4.4mmol/L). Chest and abdomen CT and serum tumor markers revealed no signs of tumor. After identification of positive NMDAR and CASPR2 antibodies, intravenous acyclovir (1.5g/day for 14 days) was given according to the patient and family’s request. Interestingly, she felt no discomfort and was completely relieved at the one-year follow-up.
3.1.3 Patient 3
An old (ranging 70–75 years old) woman presented with headache, limb weakness, and slow response for 20 days, and then developed disturbance of consciousness and respiratory failure dependent of ventilator. Neurological examination revealed impairment of memory, attention and orientation. Cerebral MRI revealed multifocal T2/FLAIR hyperintensities mostly involving the temporal lobe, parietal lobe, and basal ganglia area (Figure. 1C). CSF analysis showed the number of cells was 30/µl, the level of protein was 77mg/dL, and the glucose level was noraml. Chest and abdomen CT and serum tumor markers revealed no signs of tumors. After identification of positive NMDAR and CASPR2 antibodies, high-dose methylprednisolone were intravenously injected (0.5g, 0.25g, 3 days for each dosage), and accompanied with IVIG (0.4g/kg for 5 days). Oral prednisone (50mg daily) was administered for 8 weeks, and then gradually reduced the dose by 5 mg every 2 weeks until the final withdrawal. The patient gradually recovered and was able to live independently. No any tumors were found at the 6-month follow-up.
3.1.4 Patient 4
An old (ranging 66–70 years old) man presented with headache, dizziness, slurred speech, and slow response for 3 days. Neurological examination revealed impairments of cognition, attention and orientation. Cerebral MRI revealed no abnormalities (Figure. 1D). CSF analysis showed no abnormalities. Chest and abdominal CT showed multiple small nodules in both lungs, but there was no evidence of malignancy, since the patient refused biopsy. Serum tumor markers were no abnormalities. After identification of positive NMDAR and GABABR antibodies, dexamethasone was intravenously injected (0.5g, 0.25g, 3 days for each dosage), and accompanied with IVIG (0.4g/kg for 5 days). Oral prednisone (45mg daily) was administered for 8 weeks, and then gradually reduced the dose by 5 mg every 2 weeks until the final withdrawal. The patient's symptoms were greatly improved after immunological therapy. The multiple pulmonary nodules did not show obviously malignant transformation after 6 months.
3.1.5 Patient 5
A young (ranging 10–15 years old) boy was admitted with depression, severe insomnia, visual and acoustic hallucinations, and a suicide attempt for a half month, and then developed disturbance of consciousness and recurrent seizures. Cerebral MRI showed no abnormal findings (Figure. 1E). EEG indicated severe abnormality. CSF analysis showed no abnormalities. Chest and abdomen CT showed multiple enlarged lymph nodes in the mediastinum, bilateral axilla, retroperitoneum, and bilateral inguinal, which were proven to be lymphadenitis by lymph node biopsy. After identification of positive NMDAR and GABABR antibodies, the patient was treated sequentially with plasmapheresis, intravenous high-dose methylprednisolone (1.0g, 0.5g, 0.25g, 3 days for each dosage), IVIG (0.4g/kg for 5 days ), and oral mycophenolate mofetil (0.5g, 2 times daily). The patient’s symptoms were gradually improved. No tumors were found at one-year follow-up.
3.1.6 Patient 6
An old (ranging 70–75 years old) man presented with cognitive impairment for half a month and rapidly progressed to speech disorder, cognitive impairment, and confusion. Cerebral MRI revealed multifocal T2/FLAIR and DWI hyperintensities involving the left temporal and right occipital cortex (Figure. 1F). CSF analysis showed the number of cells was 1/µl, and the level of protein was 51mg/dL, and the level of glucose was normal. Enhanced chest CT revealed a nodule in the upper right lung, which was suspected a lung cancer (Figure. 2A and B), but patients and families refused further evaluations and treatments. The patient was identified with positive AMPAR2 and Hu antibodies, and died at 4 months after discharge.
3.1.7 Patient 7
An old (ranging 66–70 years old) woman presented with dizziness, slow response, memory impairment, and sleep disorder for half a month. Cerebral MRI revealed hyperintensities on T2/FLAIR involving the bilateral temporal and insular cortex (Figure. 1G). CSF analysis showed no abnormalities. Chest and abdomen CT and serum tumor markers revealed no signs of tumor. After indentification of positive LGI1 and IGLON5 antibodies, the patient was treated with intravenous high-dose methylprednisolone (1.0g, 0.5g, 0.25g, 3 days for each dosage), IVIG ( 0.4g/kg for 5 days), and oral mycophenolate mofetil (0.5g, 2 times daily). Oral prednisone (60mg daily) was administered for 4 weeks, and then gradually reduced the dose by 5 mg every 2 weeks until the final withdrawal. The patient’s symptoms were gradually improved at the one-year follow-up.
3.1.8 Patient 8
An old (ranging 66–70 years old) man presented with memory decline, speech disorder, and confusion for ten days, and then developed recurrent seizures, auditory hallucinations, and cognitive impairment. Neurological examination revealed cognitive impairment, slow response, and positive babinski’s sign. Cerebral MRI revealed T2/FLAIR hyperintensities involving the right hippocampus and brain stem (Figure. 1H). CSF analysis showed the number of cells was 2/µl, the level of protein was 56mg/dL, and the level of glucose was normal. Chest and abdomen CT and serum tumor markers revealed no signs of tumor. After identification of positive LGI1 and CASPR2 antibodies, high-dose methylprednisolone (1.0g, 0.5g, 0.25g, 3 days for each dosage) and IVIG (0.4g/kg for 5 days) were administered simultaneously. During the 6 months of follow-up, the patient's cognitive function improved and was free of seizures.
3.1.9 Patient 9
An old (ranging 60–65 years old) man was admitted with recurrent seizures for one day, and then developed rapidly to coma and severe respiratory insufficiency. Cerebral MRI showed no abnormalities (Figure. 1I). CSF analysis showed the number of cells was 4/µl, the level of protein was 95 mg/dL, and the level of glucose was normal. Enhanced chest CT revealed multiple nodules in bilateral lung (Figure. 2C) and multiple markedly enlarged lymph nodes in the right hilum and mediastinum (Figure. 2D), which were considered malignant lesions probably. After identification of positive NMDAR, GABABR and GAD65 antibodies, high-dose methylprednisolone (1.0g, 0.5g, 0.25g, 3 days for each dosage) and IVIG (0.4g/kg for 5 days ) were administered simultaneously. No significant improvement was observed, so the family preferred to hospice care instead of further pathological biopsy and treatments. At last, the patient died 3 days after discharge.
3.2 Literature summarization
3.2.1 Retrieving record
The enrollment procedure in this study was depicted in Figure. 3. A total of 873 records were identified in multiple databases by the selected keywords. After removing the duplication records, 71 of 873 records were screened for AE cases with co-existence of multiple anti-neuronal antibodies. 35 of 71 records were excluded due to the presence of auto-antibodies associated with CNS demyelination, and then 12 records were excluded due to diagnosis ineligibility with evidence insufficiency (n = 2), repeated report (n = 4), and non-clinical cases records (n = 6). Finally, 24 records (74 cases) were qualified to summarize the clinical data of AE with co-existence of multiple anti-neuronal antibodies.
3.2.2 Clinical summarization
We summarized the clinical data of 74 cases from the literature and the 9 cases described above, which included 71 cases from mainland China and 12 cases from outside of China. The male patients accounted for 62.6% (52/83). The median age was 59 years (interquartile range [IQR] 45–66 years; range 4–84 years). The clinical manifestations of all cases presented with typical encephalitis symptoms. Among the 76 cases available to the detailed clinical symptoms (Table 2), cognitive impairment was the most commonly clinical presentation (53/76, 69.7%), followed by seizure (47/76, 61.8%), psychiatric symptom (24/76, 31.6%), disturbed consciousness (18/76, 23.7%), sleep disorder (11/76, 14.5%), peripheral nerve symptom (11/76, 14.5%), hallucination (10/76, 13.1%), cerebellar symptoms (7/76, 9.2%). In addition, Li HH et al.[3] reported a CASPR2 encephalitis was combined with Tr antibody in one patient, who presented with ocular muscle palsy and chorea. Ren et al.[4] reported a AMPAR encephalitis was combined with Hu antibody in one patient, who presented with psychiatric disturbance and bulbar palsy. Li H et al.[5] reported a patient with co-existence of GABAB and CRMP5/CV2 antibodies, who presented with Lambert–Eaton myasthenic syndrome.
Table 2
Clinical characteristics of 83 cases of AE with co-existence of multiple anti-neuronal antibodies.
Characteristics
|
Values
|
Sex, n(%)
|
Male
|
52(62.6%)
|
Female
|
31(37.4%)
|
Age, y, median (range)
|
59(4–84)
|
༜20, n(%)
|
8(9.6%)
|
20–40, n(%)
|
9(10.8%)
|
40–60, n(%)
|
31(37.3%)
|
༞60, n(%)
|
35(42.2%)
|
Presenting symptom (n = 76)
|
Cognitive impairment, n(%)
|
53(69.7%)
|
Seizure, n(%)
|
47(61.8%)
|
Psychosis, n(%)
|
24(31.6%)
|
Disturbed consciousness, n(%)
|
18(23.7%)
|
Sleep disorder, n(%)
|
11(14.5%)
|
Peripheral nerve symptom, n(%)
|
11(14.5%)
|
Hallucination, n(%)
|
10(13.1%)
|
Cerebellar symptoms, n(%)
|
7(9.2%)
|
Tumor, n(%)
|
39(46.9%)
|
lung cancer
|
28(33.7%)
|
Mediastinum tumor
|
3(3.6%)
|
Thymoma
|
2(2.4%)
|
Ovarian teratoma
|
2(2.4%)
|
Others*
|
4(4.8%)
|
Outcomes, n(%)
|
Improvement
|
57(68.6%)
|
Died
|
26(31.3%)
|
*Hysteromyoma, breast cancer, bile duct cancer, and gastric cancer
3.2.3 Laboratory data (Table 3)
Forty-eight patients had EEG examination with slow wave activity in 28 cases, epileptic discharges in 12 cases, and mild or no abnormalities in 9 cases. Cerebral MRI were available in 66 cases, 33 cases (33/66, 50.0%) of which showed abnormal lesions. In brief,, the high-intensity lesions were mainly distributed in the hippocampus (23/66, 34.8%), temporal lobes (18/66, 27.2%), basal ganglia (6/66, 9.1%), frontal lobe (6/66, 9.1%), occipital lobe (4/66, 6.0%), brainstem (4/66, 6.1%), and parietal lobe (2/66, 3.0%), which were consistent with the imaging feature of typical autoimmune encephalitis.
Serum and CSF samples in all patients were screened for the panel test of anti-neuronal antibodies, which revealed that 73 cases had co-existence of two types of anti-neuronal antibodies, 8 cases had three types of antibodies, and 2 cases had four types of antibodies. GABABR and NMDAR antibodies were the two most common anti-neuronal surface antigen antibodies, reaching 37 cases (37/83, 44.6%) for both. Followed by LGI1 antibody in 17 cases (17/83, 20.5%), CASPR2 antibody in 12 cases (12/83, 14.5%), AMPAR2 antibody in 6 cases (6/83, 7.2%), IgLON5 antibody in 2 cases (2/83, 2.4%), VGKC antibody in one case (1/83, 1.2%), and DPPX antibody in one case (1/83, 1.2%). Hu antibody (18/83, 21.7%) was the most common anti-neuronal intracellular antigen antibody, followed by each of GAD65, SOX1, and Yo antibody in 8 cases (8/83, 9.6%), Ma2 antibody in 6 cases (6/83, 7.2%), each CV2 and amphiphysin antibody in 4 cases (4/83, 4.8%), Ri antibody in 2 cases (2/83, 2.4%), Tr antibody in one case (1/83, 1.2%), and Titin antibody in one case (1/83, 1.2%). The most common combination of auto-antibodies was GABABR plus Hu in 11 patients (10/83, 13.2%), followed by GABABR plus NMDAR in 10 patients (10/83, 12.0%), GABABR plus SOX1 in 6 patients (6/83, 7.2%), and NMDAR plus CASPR2 in 6 patients (6/83, 7.2%). The detailed combinations were enlisted in the Table 1, Table 3 and Figure. 4.
Table 3
Laboratory results and imaging of 83 AE cases with co-existence of multiple anti-neuronal antibodies.
Variables
|
Positive number n(%)
|
EEG (n = 48)
|
Slow activity
|
28(58.3%)
|
Epileptic activity
|
12(25.0%)
|
mild or no abnormal
|
9(18.7%)
|
Brain MRI (n = 66)
|
Frontal lobe
|
6(9.1%)
|
Temporal lobes
|
18(27.2%)
|
Parietal lobe
|
2(3.0%)
|
Occipital lobe
|
4(6.0%)
|
Hippocampus
|
23(34.8%)
|
Basal ganglia
|
6(9.1%)
|
Brainstem
|
4(6.1%)
|
No abnormalities
|
33(50.0%)
|
Antibodies of AE
|
Anti-neuronal surface antigen antibodies
|
|
GABABR
|
37(44.6%)
|
NMDAR
|
37(44.6%)
|
LGI1
|
17(20.5%)
|
CASPR2
|
12(14.5%)
|
AMPAR
|
6(7.2%)
|
IgLON5
|
2(2.4%)
|
VGKC
|
1(1.2%)
|
DPPX
|
1(1.2%)
|
Anti-neuronal intracellular antigen antibodies
|
|
Hu
|
18(21.7%)
|
GAD65
|
8(9.6%)
|
SOX 1
|
8(9.6%)
|
Yo
|
8(9.6%)
|
Ma2
|
6(7.2%)
|
CV2
|
4(4.8%)
|
Amphiphsin
|
4(4.8%)
|
Ri
|
2(2.4%)
|
Tr
|
1(1.2%)
|
Titin
|
1(1.2%)
|
3.2.3 Treatment and follow-up
Thirty-nine of 83 cases (39/83, 46.9%) were confirmed or suspected to have tumors during treatment or follow-up, in which lung cancer was the most common (28/83, 33.7%), followed by mediastinal tumor (3/63, 3.6%), thymoma (2/83, 2.4%), ovarian teratoma (2/83, 2.4%), and other tumors (4/83, 4.8%). Of the 83 cases, 58 received first-line immunotherapy (including glucocorticoids, IVIG, or plasmapheresis) and tumor removal; 15 received second-line immunotherapy (including rituximab, cyclophosphamide, or mycophenolate mofetil) after first-line immunotherapy; 3 received symptomatic drug therapy; 4 refused treatment; and 7 were unavailable to treatment details. Partial or complete recovery was achieved in 57 cases (57/83, 68.6%). Twenty-six cases (26/83, 31.3%) died during the follow-up, and 21 cases (24/26, 92.3%) were confirmed or suspected to be associated with the tumors.