Juvenile Myoclonic Epilepsy of Janz:
Case Report and Discussion
Marissa A. Broadley, Binghamton University; Martin L. Kutscher MD, Departments of Pediatrics and Neurology, New York Medical College, Valhalla, New York.
Case Report
The patient is a 16-year-old female, who presented with morning twitches. These spells occurred within 10 minutes of awakening. She would become very tremulous, her arm would jolt, and then she would drop whatever she was holding. She remained conscious during these spells. There were no absence or tonic/clonic seizures.
This patient had an unremarkable birth and development. The mother had idiopathic primarily generalized epilepsy characterized by grand mal seizures and absences, diagnosed at 11 years of age. The mother’s seizures have been well controlled with valproic acid for the past twenty years.
On physical exam the patient was normal appearing, appropriate and in no distress. Cranial nerves were normal. Optic discs were sharp and flat. No drift. 5/5 strength. Normal light touch. Reflexes 2+. Toes downgoing. Cerebellar testing revealed a fine postural tremor. Gait was normal. Examination of the skin included a strawberry hemangioma on the leg. Hyperventilation did not cause any spells.
Juvenile Myoclonic Epilepsy of Janz (JME) was considered. The patient underwent a sleep deprived awake electroencephalogram (EEG) study. The EEG study was consistent with JME, with some bursts lasting three seconds. Magnetic resonance imaging of the head was normal.
The patient was hesitant to start valproic acid because of the possibility of weight gain. Therefore, she was initially put on Diamox (acetazolamide) which controlled her seizures. However, after four months of treatment, she had lost significant weight; and was chronically nauseated, depressed and dizzy. She was then put on Depakote (divalproex sodium EC) 750mg daily. She developed thrombocytopenia and the Depakote was decreased to 500mg daily. With this dosage the thrombocytopenia subsided, while the seizures remained well controlled. However, weight gain, hair thinning, tinnitus and increased postural tremor have been moderately problematic. It was recommended that she take folic acid, selenium and zinc.
Discussion
This is a classic case of Juvenile Myoclonic Epilepsy of Janz (JME). It is necessary for doctors to be aware of this illness as it is often misdiagnosed and ignored, which can have serious consequences. What are the symptoms? How is it treated?
Historical Background and Epidemiology
JME of Janz is an idiopathic generalized epilepsy syndrome. The types of seizures that can occur in patients with JME are myoclonic jerks, generalized tonic clonic seizures (GTCS), and absence seizures. Herpin first described this syndrome in 1867. He presented a patient with jerks starting at the age of 13, which progressed to "full seizures." In 1957, Janz and Christian published descriptions on a group of patients with seizures described as "impulsive petit mal". Later, Lund and the International League Against Epilepsy termed this syndrome characterized by "impulsive petit mal" seizures as Juvenile Myoclonic Epilepsy of Janz.
Clinical Features
The age of onset is 6-36 years of age; most seizures begin between the ages of 12-18. The seizures typically occur in the morning shortly after awakening. They are bilateral myoclonic jerks that most often involve the arms and shoulders. If the myoclonic jerk is violent enough, the patient may drop things or fall to the floor. Importantly, there is no loss of consciousness during these seizures. Often, the child has become accustomed to these spells and never mentions them to their parent. Whenever any seizure disorder is being considered, it is imperative to initiate inquiry about myoclonic spells.
Generalized tonic clonic seizures occur in 95% of all JME patients. Absence seizures precede myoclonic jerks in 30% of the cases. The intellectual ability of persons with JME of Janz is normal. Physical examination, CT scan and MRI are also normal. The EEG pattern typically shows 10 – 15 Hz polyspikes and intermittent slow wave discharges. However, some patients with JME of Janz have normal EEG patterns. Some triggers of myoclonic jerks include: sleep deprivation, psychological stress, alcohol use, photic stimulation, menses and the time of day. It is a lifelong syndrome that can usually be well controlled.
One person in every 1,000 – 2,000 has this disorder worldwide, which occurs slightly more often in females. JME accounts for approximately 7% of all idiopathic epilepsy patients. However, there are probably more instances of JME that are misdiagnosed or ignored.
JME is an inherited disorder. One third of people with JME have a family member with epilepsy. Ten percent of all relatives without known seizures will still have abnormal EEG patterns. Brain tumor, brain trauma and encephalitis are not causes of this syndrome. Hence it is considered idiopathic.
Differential Diagnosis
Subacute sclerosing panencephalitis (SSPE), diagnosed with similar spike-wave EEG patterns as JME of Janz. This disease occurs among the same age group as people with JME. It is a disease of the central nervous system that is caused by the measles virus. Convulsions, intellectual deterioration and paralysis may occur.
Creutzfield- Jacob disease, diagnosed with similar spike-wave EEG patterns as JME of Janz. This is a rare, viral degenerative encephalopathy.
Classic Absence Epilepsy, also known as petit mal epilepsy. These seizures typically last less than 20 seconds, and usually involve a stare and movements of the mouth and hands. These seizures most often begin in childhood and are outgrown 75% of the time.
Generalized Tonic-Clonic Seizures, a type of grand mal seizure that involves the whole brain. Loss of consciousness, shaking, falling and jerking occur.
Myoclonus, a sudden jerk in the process of falling asleep. This may be perfectly normal.
Pseudoseizure, resembles a seizure but is psychological in origin.
Course and Prognosis
JME of Janz is not outgrown. Many patients do very well on one anticonvulsant.
This patient has only had a few spells in her life. She has had no other neurological problems. Most importantly this case was accurately diagnosed within weeks of the symptoms occurring. Hopefully, seizure control will persist and she will continue to live a normal and productive life.
Psychiatric disorders are higher among this cohort. In one study, 7 out 23 patients with JME of Janz reported psychiatric disorders--most often depression. This study also concluded that 18% of first-degree relatives of patients with JME reported a psychiatric diagnosis.
Treatment
There are several antiepileptic drugs (AEDs) that can be used to treat JME of Janz: valproate (Depakote, Depakene), acetazolamide (Diamox), clonazepam (Klonopin), phenobarbital, primidone (Mysoline), lamotrigine (Lamictal) and topiramate (Topamax). Some AEDs may trigger myoclonic seizures. These include: carbamazepine (Tegretol), ethosuximide (Zarontin) and phenytoin (Dilantin). Most patients with JME of Janz have seizure control on monotherapy.
The typical drug of choice to treat JME of Janz is sodium valproate (Depakote, Depakene). 80% of patients who suffer from JME gain seizure control on valproate. Lamotrigine (Lamictal) is good alternative drug. This drug is fairly new in the United States but has been used in Europe for some time. Even though it has been highly effective treating JME of Janz, it has been reported to sometimes trigger myoclonic seizures.
Acetazolamide (Diamox), clonazepam (Klonopin), phenobarbital and primidone (Mysoline) are used less often to treat JME of Janz. These drugs are often used as secondary drug treatment. Physicians should respect the patient’s possible complaint of "not feeling right" with AEDs and should consider changing the medication if this occurs. Surgery is not considered in patients with JME of Janz.
Summary
Juvenile Myoclonic Epilepsy (JME) of Janz is characterized by:
Onset in adolescence of myoclonic, absence, and tonic/clonic seizures. (Thus, the existence of possible co-existent myoclonic seizures should be investigated while evaluating absence or tonic/clonic seizures.)
Unlikely to be outgrown.
Associated with normal intelligence.
Good prognosis to be controlled only by specific anticonvulsants, including valproic acid and lamotrigine.
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