EEG with extreme delta brush in young female with methotrexate neurotoxicity supports NMDA receptor involvement

Effectiveness of intra-thecal methotrexate in refractory Anti-N-methyl-d-aspartate receptor encephalitis

BACKGROUND

Anti-N-methyl-d-aspartate "anti-NMDA" receptor encephalitis is one of the most common autoimmune encephalitis for which first- and second-line therapies have been recommended following international consensus. However, some refractory cases do not respond to the first- and second-line therapy and require further immune-modulatory therapies such as intra-thecal methotrexate. In this study, we reviewed six confirmed cases of refractory anti-NMDA receptor encephalitis from two tertiary centers in Saudi Arabia that required escalation of treatment and received a six-month course of intra-thecal methotrexate. The aim of this study was to evaluate the effectiveness of intra-thecal methotrexate as immunomodulatory therapy for refractory anti-NMDA receptor encephalitis.

METHODS

We retrospectively evaluated six confirmed cases of refractory anti-NMDA receptor encephalitis who did not improve after first- and second-line therapy and received monthly intra-thecal methotrexate treatment course for six consecutive months. We reviewed patient demography, underlying etiologies, and compared their modified Rankin score prior to receiving intra-thecal methotrexate and six months after completing the treatment.

RESULTS

Three of the six patients showed a marked response to intra-thecal methotrexate with a modified Rankin scale of 0-1 at 6-month follow-up. None of the patients experienced any side effects during or after intra-thecal methotrexate treatment, and no flareups were observed.

CONCLUSION

Intra-thecal methotrexate may be a potentially effective and relatively safe escalation option for immunomodulatory therapy of refractory anti-NMDA receptor encephalitis. Future studies on intra-thecal methotrexate -specific treatment regimens may further support its utility, efficacy, and safety in treating refractory anti-NMDA receptor encephalitis.

Ketamine as an Adjunct for Treatment of Methotrexate-induced Neurotoxicity

Methotrexate (MTX) is used in the treatment of several childhood cancers and is a main component of the treatment regimen for osteosarcoma. MTX has been linked with side effects of varying severity; headaches, nausea, emesis, lethargy, blurred vision, aphasia, hemiparesis, paresis, convulsions, leukoencephalopathy, and arachnoiditis are symptoms of MTX toxicity. MTX-induced neurotoxicity can occur in up to 15% of patients receiving high-dose MTX. The effects may be transient but can have life-threatening implications, sometimes requiring intubation for respiratory support and airway protection. Elevated homocysteine levels in the cerebrospinal fluid are documented in cases of MTX-induced neurotoxicity; dextromethorphan is used as an initial treatment for MTX-induced neurotoxicity as it works as a noncompetitive antagonist for the N-methyl D-aspartate receptors and suppresses homocysteine activity. In severe cases requiring intubation, medications for sedation are utilized. Ketamine is also an N-methyl D-aspartate receptor antagonist, and as such, may be considered as an optimal treatment choice when sedation is required. We describe the use of ketamine in a pediatric patient with MTX-induced neurotoxicity. The use of ketamine in the treatment of MTX-induced neurotoxicity has not been described in the literature.

A refractory anti-NMDA receptor encephalitis successfully treated by bilateral salpingo-oophorectomy and intrathecal injection of methotrexate and dexamethasone: a case report

Introduction

Anti-N-methyl-D-aspartate (anti-NMDA) receptor encephalitis is an autoimmune-mediated disease that is common in young female patients with ovarian teratomas. With appropriate immunotherapy, most patients achieve a good prognosis. Nevertheless, some patients may be refractory to first- and second-line immunotherapy, thus alternative treatments are required for these patients.

Case presentation: We present a case of anti-NMDA receptor encephalitis with ovarian teratoma. After the prompt removal of the teratoma and intense immunotherapy was administered, including an intravenous methylprednisolone pulse, intravenous immunoglobin, plasmapheresis, immunoadsorption, intravenous cyclophosphamide, and rituximab, the patient’s neurologic status did not improve. Bilateral salpingo-oophorectomy was then conducted, and intrathecal injection of methotrexate (MTX) and dexamethasone (DXM) was performed. The patient’s neurological symptoms improved dramatically, and she achieved a good prognosis after 23 months.

Conclusions

Intrathecal injection of MTX and DXM may be beneficial for treatment of refractory cases of anti-NMDA receptor encephalitis. Additional research is required to elucidate the mechanisms of intrathecal treatment with this therapy.

Persistent extreme delta brush in anti-NMDA-receptor encephalitis: Does it portend a poor prognosis?

We describe an adolescent girl with non-paraneoplastic anti-NMDA-receptor encephalitis (ANMDARE), who despite persistence of the extreme delta brush (EDB) pattern for nearly 2 years in her serial EEGs, she exhibited a speedy and sustained response to immunotherapy. To the best of our knowledge, our patient had the longest persistence of the EDB pattern on EEG reported to date. Our patient illustrates that, although presence of EDB supports the diagnosis of ANMDARE, its presence and persistence may not be a reliable predictor of response to immunotherapy and overall clinical prognosis.

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Extreme delta brush (EBD) supports diagnosis of anti-NMDA-R encephalitis (ANMDARE).

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EDB may persist for a long time despite complete resolution of symptoms of ANMDARE.

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EDB may not be reliable biomarker of response to immunotherapy and outcome.

Predictive values and specificity of electroencephalographic findings in autoimmune encephalitis diagnosis

OBJECTIVE

Early diagnosis of autoimmune encephalitis (AE) to not delay treatment is challenging but needed in practice. Most previous evidences of electroencephalographic (EEG) findings in AE were derived from descriptive studies. Given paucity of evidence of specific EEG findings to help with early diagnosis of AE, this study aimed to ascertain specific EEG findings and assess their predictive values in diagnosis of AE.

METHODS

We included all cases with AE in our institution from January 2013 to June 2017. Cases were matched with controls by age and level of consciousness (1:2 ratio). Potential confounders for EEG findings collected as baseline characteristics were compared. Two epileptologists independently reviewed EEGs. Standardized terminology, definitions, and scoring system of EEG findings were employed. Logistic regression analysis was performed, and diagnostic performance of significant EEG features was assessed.

RESULTS

Twenty cases and 40 controls were included in this study. Poorly sustained posterior dominant rhythm (PDR) was significantly associated with AE (p = 0.007) and even more predictive in anti-N-methyl-d-aspartate (NMDA) encephalitis. Inter-rater agreement (kappa) was 0.714. None of the cases had normal EEG nor Grand Total EEG (GTE) score < 4 (negative predictive value (NPV) of 100%). Specificity of well sustained PDR to exclude the diagnosis of anti-NMDA encephalitis was high (91.67%).

CONCLUSIONS

Simple EEG assessment can be used to help exclude AE. When AE is suspected, careful assessment of the sustainment of the PDR is warranted. The NPV of GTE score < 4 and specificity of well sustained PDR can be simply used to differentiate many conditions from AE.