Status Epilepticus Associated with Mycoplasma pneumoniae Encephalitis in Children: Good Prognosis Following Early Diagnosis and Treatment
Mycoplasma pneumoniae is a well-known pathogen responsible for respiratory tract infections in children. However, its impact extends beyond the respiratory system, as it can cause immune-related injuries in multiple organs and tissues. Among these, central nervous system (CNS) involvement is reported in 5% to 7% of patients with M. pneumoniae infection. The clinical manifestations of M. pneumoniae encephalitis are highly heterogeneous, with seizures occurring in more than half of the patients during the acute phase. In severe cases, status epilepticus (SE) can develop, which is a critical neurological condition in children. Despite the recognized frequency of M. pneumoniae encephalitis, reports of this condition in children with SE are rare. This study focuses on the clinical characteristics, diagnostic criteria, treatment strategies, and prognosis of children with M. pneumoniae encephalitis complicated by SE, emphasizing the importance of early diagnosis and treatment for a favorable outcome.
Diagnostic Criteria for M. pneumoniae Encephalitis
The diagnosis of M. pneumoniae encephalitis can be challenging due to its heterogeneous presentation. A three-level classification system has been proposed to aid in diagnosis:
- Highly Suspected: Positive cerebrospinal fluid (CSF) or polymerase chain reaction (PCR) results, with or without positive serological test results, or positive pharyngeal swab culture/PCR results with positive serological test results.
- Suspected: Positive serology with negative pharyngeal swab, CSF, and PCR results, or positive pharyngeal swab/PCR results with negative serological test results, and no other infectious pathogens.
- Not Excluded: Positive serological test results with negative pharyngeal swab, CSF, and PCR results, with at least one confirmed infectious pathogen.
This study directly tested M. pneumoniae in the CSF of children with encephalitis complicated by SE, providing direct evidence of CNS involvement by this pathogen. Early identification and treatment in four cases resulted in satisfactory outcomes, highlighting the importance of timely intervention.
Clinical Manifestations
The study included four children (three boys and one girl) aged 3, 4, 5, and 8 years. All cases presented with acute onset, and the duration of hospitalization ranged from 4 to 14 days. Initial symptoms included fever with peak temperatures of 39°C to 40°C, occurring two to four times daily. Respiratory symptoms such as cough were noted in two patients, while three patients exhibited disturbances of consciousness (Glasgow Coma Scale scores of 11–12). One patient was unconscious. The types of SE varied among the cases, including myoclonus secondary to tonic-clonic seizures, generalized tonic-clonic seizures, complex partial seizures, and generalized tonic-clonic seizures combined with subclinical electrical discharges. Neck rigidity was observed in one patient, while the other three showed no pathogenic neurological signs.
Examination Results
Lumbar puncture was performed on the 4th, 6th, 7th, and 14th days after disease onset in each patient. Routine and biochemical CSF examinations were within normal ranges, and no viral antibodies were detected. Bacterial culture, acid-fast staining, and ink staining results were negative. However, the CSF was positive for M. pneumoniae RNA. Video electroencephalography (EEG) revealed a slow-wave background rhythm of 1.5 to 3.0 Hz in all patients, with slow waves observed in each hemisphere. The interictal interval contained multifocal epileptiform discharges, and electrical status was observed in one patient. Cranial magnetic resonance imaging (MRI) findings were abnormal in three patients: two exhibited long T1 and T2 signals in the hippocampus, and one showed demyelination of the paraventricular white matter. No definite abnormalities were observed in the remaining case.
Therapeutic Response and Prognosis
All four patients were treated with azithromycin for two weeks (5 days per week). Additionally, three patients received dexamethasone, two were treated with intravenous immunoglobulin (IVIG), and one received combined IVIG and glucocorticoids. Following treatment, body temperature normalized in all patients, and three regained consciousness. Two patients were free of epileptic seizures after treatment, while the remaining two continued oral antiepileptic drugs (levetiracetam and topiramate) to reduce seizure frequency. Follow-up EEGs showed improved background activity and significantly decreased epileptiform discharges in all cases. Cranial MRI revealed varying degrees of brain atrophy in all patients, indicating severe brain parenchyma damage during the acute phase.
Discussion
M. pneumoniae encephalitis is associated with epileptic seizures in 41% to 48% of cases, with SE accounting for approximately 50% of these seizures. In this study, three children exhibited SE, while electrical status was observed in the remaining patient. EEG abnormalities were severe in all cases, reflecting significant brain damage during the acute phase. However, timely treatment led to improved EEG findings, with no recurrence of SE. The prognosis of M. pneumoniae encephalitis with SE is relatively good, and SE can be effectively controlled with early intervention.
Pathological changes associated with M. pneumoniae encephalitis include demyelination of white matter, inflammatory infiltration, perivascular edema, and glial cell proliferation. Imaging findings can range from normal to focal changes, diffuse edema, or abnormal intensity in the gray/white matter. In this study, three patients exhibited abnormal cranial MRI findings, including demyelinating changes in the paraventricular white matter and abnormal signals in the hippocampus. These findings suggest that MRI abnormalities are common in children with M. pneumoniae encephalitis complicated by SE, although lesion location is nonspecific.
M. pneumoniae infection can lead to immune-mediated damage, and immunotherapy has been shown to improve symptoms. In this study, IVIG and dexamethasone were used in combination with azithromycin, yielding positive outcomes. This suggests that while M. pneumoniae infection is the primary mechanism in the early disease stage, immune responses also play a significant role. Therefore, early treatment strategies should include macrolides in conjunction with immunotherapy.
Prognosis and Follow-Up
The prognosis of M. pneumoniae encephalitis is generally poor, with a high mortality rate and significant neurological sequelae in survivors. However, in this study, all four patients were treated promptly with azithromycin and immunotherapy, resulting in symptom control within 1 to 2 weeks. No cases of refractory SE occurred, and the rate of epileptic seizures decreased significantly after treatment with oral antiepileptic drugs. Cognitive impairment was not observed in any of the children. Although brain atrophy was noted on follow-up MRIs, the overall prognosis was favorable, underscoring the importance of early diagnosis and treatment.
Conclusion
M. pneumoniae encephalitis with SE primarily affects preschool-aged children and is often associated with abnormal MRI findings. Early diagnosis and treatment are crucial for controlling symptoms and improving prognosis. The use of macrolides in combination with immunotherapy appears to be effective in managing this condition. Further studies with more extensive neuropsychological testing are needed to validate these findings and optimize treatment strategies.
doi.org/10.1097/CM9.0000000000000233
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