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Analysis of the tremor in juvenile myoclonic epilepsy
Zeynep Aydin-Özemir1, Zeliha Matur2, Betul Baykan3
1Istanbul University, Istanbul Faculty of Medicine, Departments of Neurology and Clinical Neurophysiology, Istanbul, Turkey; Umraniye Training And Research Hospital, Department of Neurology, Istanbul, Turkey.
Purpose:
We aimed to investigate juvenile myoclonic epilepsy (JME) patients complaining of tremor unrelated to valproate (VPA) treatment and evaluate if there were differences between JME patients with and without tremor and essential tremor (ET) patients to exclude comorbidity.
Methods:
Fifteen JME cases with the complaint of tremor, 14 JME patients without tremor, 14 patients with ET and 14 healthy subjects (HS) were included. Regularity, frequency and amplitude of the tremor and superimposed myoclonia were assessed by accelerometric analysis. Cortical SEPs evoked by the stimulation of the median nerve were recorded bilaterally. Clinical and neurophysiologic features were statistically compared between the groups.
Findings:
Amplitude of postural tremor of the left hand was significantly increased in the ET group compared to JME patients with tremor, but there were no differences regarding to frequency. Strikingly, there were superimposed irregular, low-amplitude inconstant myoclonic jerks located to distal part of the fingers in JME group with tremor. Initial frequency of myoclonic seizures was also significantly higher in this group compared to JME patients without tremor but this difference disappeared after treatment. The group of JME with tremor had the highest N20-P25 and P25-N35 amplitudes, followed by JME without tremor, ET and HS, respectively.
Conclusion:
Tremulous hand movements in JME resembled ET, but their amplitude was lower and characterized with accompanying irregular myoclonic jerks. The presence of tremor in JME patients should be taken into consideration to create more homogeneous groups in genetic and pathophysiological studies of JME.
Insights
Juvenile myoclonic epilepsy (JME) patients with tremor show distinct characteristics, including irregular myoclonic jerks, differentiating them from essential tremor (ET). These findings aid in classifying JME patients for research.
Area of Science:
- Neurology
- Epileptology
- Movement Disorders
Background:
- Juvenile myoclonic epilepsy (JME) is a common epilepsy syndrome.
- Tremor can be a presenting symptom in JME, sometimes unrelated to medication.
- Distinguishing JME-associated tremor from other tremor disorders like essential tremor (ET) is crucial for accurate diagnosis and research.
Purpose of the Study:
- To investigate tremor in JME patients not associated with valproate (VPA) treatment.
- To differentiate between JME patients with and without tremor.
- To compare JME patients with tremor to essential tremor (ET) patients and healthy subjects (HS) to exclude comorbidity.
Main Methods:
- Inclusion of four groups: JME with tremor (15), JME without tremor (14), ET (14), and HS (14).
- Accelerometric analysis to assess tremor regularity, frequency, and amplitude, and superimposed myoclonia.
- Recording of cortical somatosensory evoked potentials (SEPs) via median nerve stimulation.
- Statistical comparison of clinical and neurophysiological features across groups.
Main Results:
- JME patients with tremor exhibited superimposed irregular, low-amplitude myoclonic jerks.
- ET patients showed significantly higher postural tremor amplitude than JME patients with tremor.
- JME patients with tremor had higher N20-P25 and P25-N35 SEP amplitudes compared to other groups.
Conclusions:
- Tremulous hand movements in JME resemble ET but are characterized by lower amplitude and accompanying myoclonic jerks.
- Identifying tremor in JME is important for creating more homogeneous patient cohorts for genetic and pathophysiological studies.
- These findings highlight distinct neurophysiological characteristics of tremor in JME.
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