- Myoclonic atonic seizures are the defining feature.
- Tonic seizures are not a predominant seizure type in this syndrome.
- The syndrome is considered an epileptic encephalopathy.
- The EEG usually has a normal background particularly at onset of syndrome, with frequent generalised discharges of 2 to 4 Hz spike/polyspike waves.
- Non-convulsive status epilepticus is a frequent feature.
- Outcome is variable but for a subset is favourable.
- Treatment: drugs used in generalised epilepsies, such as: sodium valproate, ethosuximide, clobazam are often efficacious. Early use of the ketogenic diet for drug resistant epilepsy is recommended.
- Consider early referral to Paediatric Neurology.
According to the NICE Guideline: The Epilepsies:
- The seizure type(s) and epilepsy syndrome, aetiology, and co-morbidity should be determined.
- If there is diagnostic uncertainty, individuals should be referred to tertiary services soon (within 4 weeks) for further assessment.
- 1 in 10,000 children.
- ~1% to 2% of all childhood epilepsies.
- Predominance of male sex, in most series: 2:1. Onset in first year equal.
Age at onset
- 6 months to 6 years, peak 2-4 years.
- There is often a strong family history of epilepsy including other epilepsy syndromes.
- A proportion of these patients are SCN1A positive.
- Other genes affecting the sodium channel may be seen, SCN1B and SCN2A.
- SLC2A1 (Glucose Transporter gene) is noted in a small subset of patients (4/84 patients in one series).
- 14% of 85 patients in one series had pathogenic genetic variants found on exome, including new genes (Epilepsia, 2020).
Signs | Symptoms
Myoclonic atonic seizure is the defining seizure type (100%), manifesting with symmetrical myoclonic jerks involving the neck, shoulders, arms and legs, immediately followed by loss of muscle tone (atonic component). They cause lightning-like falls, head nodding, or bending of the knees.
- More than half of patients have brief absence seizures, often together with myoclonic jerks, facial myoclonias, and atonic events.
- Atonic and absence seizures are frequent and sometimes many occur each day.
- Tonic seizures are not a major feature.
- Non-convulsive status epilepticus for hours or days affects 1/3 of patients.
- In 2/3's of patients, febrile and non-febrile generalised tonic-clonic seizures appear first, several months prior to myoclonic atonic seizures.
- The seizure frequency can become very severe and sometimes refractory to treatment.
Neurological and mental state
- Often have normal development prior to the onset of seizures.
- Lennox Gastaut Syndrome.
- Atypical childhood epilepsy with centrotemporal spikes.
- Dravet syndrome.
- Usually normal background particularly at syndrome onset, with frequent generalised discharges of 2 to 4 Hz spike/polyspike wave. With time, background may show generalised slowing.
- Epileptogenic activity increases in sleep.
- Photic stimulation may trigger generalised spike/wave or myoclonic atonic seizures.
- Non-convulsive status leads to continuous or discontinuous and repetitive 2 to 4 Hz spike/wave.
- Symptomatic causes need to be excluded.
In publication (Epilepsia 2020) 101 patients with myoclonic atonic epilepsy were studied. A high proportion had significant comorbidity:
- Intellectual disability - 62%
- Low adaptive behavioural scores - 69%
- Autism - 24%
- ADHD - 37%
Prognosis dependent on:
- Age of onset (younger less favourable)
- Nature of seizures (for example, presence of tonic seizures and interictal EEG findings)
- A subset have a favourable outcome.
- 2/3 achieve seizure remission:
- Myoclonic atonic seizures remit with higher frequency up to 89%, but may be ongoing tonic-clonic seizures.
- Cognitive prognosis strongly linked to whether seizures remit.
Ataxia and motor linguistic disturbances may emerge.
Early referral to paediatric neurology recommended.
- Sodium valproate
- Combination therapy of sodium valproate and lamotrigine may be helpful.
- In drug-resistant cases, early introduction of the ketogenic diet can be very effective.
- levetiracetam, acetazolamide, sulthiame.
- carbamazepine, vigabatrin.
Discussion with family
- Epilepsy Medical Record
- Drug Handout
- Potential of performing baseline educational assessment (through school counsellor).
Epilepsy Action (UK) have information for Parents on Epilepsy with Myoclonic Astatic Seizures (Doose Syndrome)
- Guerrini R, Aicardi J. Epileptic encephalopathies with myoclonic seizures in infants and children (severe myoclonic epilepsy and myoclonic-astatic epilepsy). J Clin Neurophysiol. 2003 Nov-Dec;20(6):449-61.
- Nickels K, Thibert R, Rau S, Demarest S, Wirrell E, Kossoff EH, Joshi C, Nangia S, Shellhaas R; Pediatric Epilepsy Research Consortium. How do we diagnose and treat epilepsy with myoclonic-atonic seizures (Doose syndrome)? Results of the Pediatric Epilepsy Research Consortium survey. Epilepsy Res. 2018 Aug;144:14-19.
- Panayiotopoulos CP. The epilepsies: Seizures, syndromes and management: Based on the ILAE classifications and practice parameter guidelines. Chipping Norton, Oxfordshire: Bladen Medical Publishing; 2005.
- Roger J, Bureau M, Dravet C, Genton P, Tassinari CA, Wolf P, editors. Epileptic syndromes in infancy, childhood and adolescence (4th ed). Montrouge, France: John Libbey Eurotext Ltd; 2005.
- Scheffer IE, Wallace R, Mulley JC, Berkovic SF. Clinical and molecular genetics of myoclonic-astatic epilepsy and severe myoclonic epilepsy in infancy (Dravet syndrome). Brain Dev. 2001 Nov;23(7):732-5.
- Tang S, Pal DK. Dissecting the genetic basis of myoclonic-astatic epilepsy. Epilepsia. 2012 Aug;53(8):1303-13.
- Tang, S, Addis, L, Smith, A, et al; EuroEPINOMICS‐RES Consortium. Phenotypic and genetic spectrum of epilepsy with myoclonic atonic seizures. Epilepsia. 2020; 61: 995– 1007.
Last reviewed in November 2020.