Acknowledgements and Disclosures
Please disclose any financial or other conflicts of interest that might bias your contributions, or give rise to the perception of such bias. Relevant financial ties can include consultantships, memberships in speaker's bureaus, grants, research support, salaries, royalties, ownership, equity positions, stock options, or other financial arrangements wherein you stand to gain substantially from an increase of stock value or corporate revenues.

Disclosures and acknowledgements will be linked to the author name(s) and will display along with appointments and affiliations. Disclosures, acknowledgements, and affiliations can be entered and updated via the "Update My Profile" link in the Online Submission System. Alternatively, you may send such information along with your updated manuscript.

Thumbnail
So that MedLink Corporation can highlight your clinical summary and your authorship on the MedLink Neurology home page and in our weekly email to subscribers, we ask that you provide here a brief overview of your subject (about 50 to 100 words) aimed at enticing readers to view this clinical summary. For updates, please include a sentence that refers to something new you have added. Refer to yourself in the 3rd person (eg, Dr. Doe of Superior Institution explains the basics…). For more information and examples of thumbnails, please see the Instructions to Authors, which can be downloaded from your "My Writing Assignments" page in the Online Submission System (http://www.medlinkoss.com).

Current thumbnail: Myclonic-atonic seizures are a particular variant of generalized myoclonic seizures in which the jerk is immediately followed by an atonia. Clearly, the jerk is correlated with a generalized spike and the atonia with a generalized slow wave. Some seizures may exhibit a series of spikes followed by slow waves, at a frequency of approximately 3Hz, lasting in total no more than one second. This type of seizure generates severe drop attacks. It is the main component of the myoclonic-astatic epilepsy.:

Historical Note and Nomenclature
The first clinical description of falling seizures was given by Hunt in 1922 (Hunt 1922). In 1945 Lennox called it “akinetic” (Lennox 1945), but he rebaptized it “astatic” in 1951 (Lennox 1951), and included it into the “petit mal triade,” together with absences and myoclonus. However, it is not before Gastaut and Regis’ polygraphic description that a specific type of seizure with a combination of myoclonus preceding atonia was reported (Gastaut and Regis 1961). Kruse introduced the term “myoclonic-astatic” seizure (Kruse 1968), and Doose and colleagues introduced the concept of a specific clinical entity with this type of seizure being the core of the disorder (Doose et al 1970). Clearly, in addition to myoclonic-astatic epilepsy, there are patients with myoclonic-atonic seizures who have prior mental retardation and lack the characteristics of myoclonic-astatic epilepsy. However, this group of patients has never been addressed specifically.

Clinical Manifestations
The major feature is a sudden fall to the ground. It is preceded by a jerk of the axial muscles. Polygraphic recording demonstrates that there is a spike wave complex, and that the spike is usually associated with the myoclonic jerk and the slow wave with the loss of tone. In fact, a burst of spike-waves lasting 1 second with an approximately 3Hz frequency may occur. The result is that the patient, usually a child, is suddenly precipitated frontward and, because of the atonia, no protection movement is possible. There is no announcing sign, and the child is literally seized by the phenomenon. For this reason, these children experience bad injuries of the forehead and face.

A 3-year-old child had three generalized tonic clonic seizures. EEG showed generalized spike waves and slow background activity. When given carbamazepine, seizure frequency decreased slightly but soon seizures recurred and the child started falling. When he fell, parents clearly noticed that the child was projected forwards and then became atonic. He was severely hyperkinetic, and falling seizures occurred several times a day. Both contributed to determine bad injuries to the face. Two cousins suffered from idiopathic generalized epilepsy. This is a case of myoclonic astatic epilepsy.

Localization
As for most brief generalized seizures, the relative responsibility of brainstem and cortex remains a matter of strong discussion. The predominance of the contraction in the axial and flexor muscles is considered as an argument in favor of an archaic pattern, therefore, of brainstem origin. Velasco and colleagues (Velasco et al 1991) found either simultaneous activation in the thalamus and cortex or lack of activation in both, thus suggesting that the triggering zone was neither in the thalamus or the cortex. Although he suspected that it was the brainstem, the most likely site of onset is the thalamo-cortico-thalamic loop, in a manner similar to absence seizures but involving the motor strip.

Pathophysiology
Rolandic involvement is highly suggested, and maturation phenomena play a great contribution (Dulac et al 1998). The correlation of myoclonus with the spike and the slow wave with the atonia is consistent with the established significance of both these events: the spike corresponds to an excitatory event, and the slow wave to an inhibitory phenomenon. Thus, the cortex and thalamus may both be involved, within a loop characteristic of seizures of idiopathic generalized epilepsy, namely absences and myoclonus. In addition, the hyperexcitability determined by maturation would be counterbalanced by excess of inhibition, the combination of which would produce the sequence of jerk and atonia. The main difference with massive myoclonus of juvenile myoclonic epilepsy is the intensity of the jerk that also involves the lower limbs, and the inhibitory component. Both could result from overexcitability of the developing cortex, balanced by excess of inhibition. In one study with video-polygraphy study, there was a correlation between intensity of the atonia and depth of the positive component of the spike-wave complex (Oguni et al 2001).

Differential Diagnosis
Young children may fall for other reasons than epileptic seizures: clumsiness when walking, syncope, cataplexy, vestibular disorders, and psychogenic seizures may cause the child to fall. Other types of falling seizures, tonic, myoclonic, atonic and partial seizures, and epileptic spasms have to be distinguished. Although the clinical context and the interictal EEG may be helpful, it is only the video polygraphic recording that permits to conclude. However, there is at present no evidence that partial and generalized falling seizures are distinct from the pathophysiological point of view.

Diagnostic Workup
The diagnosis can only be established on the basis of video polygraphic recording. However, in the context of typical features of myoclonic-astatic epilepsy, it may not be necessary to perform such a recording. The latter is mainly needed when the clinical evidence is lacking, or when a major therapeutic decision needs to be taken.

Syndromes and Diseases in which the Seizure Type Occurs.
Myoclonic-atonic seizures mainly affect patients with myoclonic-astatic epilepsy.

Prognosis and Complications
The prognosis is difficult to determine at the onset, although male sex and late onset, after the age of 4 years are 2 features of poor prognosis (Kaminska et al 1999). It is the occurrence of myoclonic status with tonic seizures that is the major factor of poor prognosis.

Management
Treatment is that of the syndrome, the most appropriate combination being valproate and lamotrigine with ethosuximide, eventually a benzodiazepine (Dulac and Kaminska 1997). Patients should not receive carbamazepine, oxcarbazepine, vigabatrin, phenytoin, or phenobarbital that increase seizure frequency in a majority of patients. The place of levetiractam remains to be determined but promising findings (Mikaeloff et al 2003).

In practice, carbamazepine, phenobarbital, phenytoin, and oxcarbazepine should not be given to a 2- to 5-year-old child who begins with tonic-clonic seizures, before myoclonic-astatic epilepsy has been ruled out.

References Cited
Doose H, Gerken H, Leonhardt R, Volzke E, Volz C. Centrencephalic myoclonic-astatic petit mal. Clinical and genetic investigation. Neuropadiatrie 1970;2(1):59-78.

Dulac O, Kaminska A. Use of lamotrigine in Lennox-Gastaut and related epilepsy syndromes. J Child Neurol 1997;12 Suppl 1:S23-8.

Dulac O, Plouin P, Shewmon A. Myoclonus and epilepsy in childhood: 1996 Royaumont meeting. Epilepsy Res 1998;30(2):91-106.

Gastaut H, Regis H. On the subject of Lennox's "akinetic" petit mal. Epilepsia 1961;2:298-305.

Hunt JR. On the occurrence of static seizures in epilepsy. J Nerv Ment Dis 1922;56:351.

Kaminska A, Ickowicz A, Plouin P, Bru MF, Dellatolas G, Dulac O. Delineation of cryptogenic Lennox-Gastaut syndrome and myoclonic astatic epilepsy using multiple correspondence analysis. Epilepsy Res 1999:36(1):15-29.

Kruse R. Das Myoclonische-astatische Petit Mal. Berlin: Springer, 1968.

Lennox WG. Phenomena and correlates of the psychomotor triad. Neurology 1951;1:357-71.

Lennox WG. The petit mal epilepsies: their treatment with Tridione. JAMA 1945;129:1069-73.

Mikaeloff Y, de Saint-Martin A, Mancini J, et al. Topiramate: efficacy and tolerability in children according to epilepsy syndromes. Epilepsy Res 2003;53(3):225-32.

Oguni H, Fukuyama Y, Tanaka T, et al. Myoclonic-astatic epilepsy of early childhood--clinical and EEG analysis of myoclonic-astatic seizures, and discussions on the nosology of the syndrome. Brain Dev 2001;23(7):757-64.

Velasco M, Velasco F, Alcala H, Davila G, Diaz-de-Leon AE. Epileptiform EEG activity of the centromedian thalamic nuclei in children with intractable generalized seizures of the Lennox-Gastaut syndrome. Epilepsia 1991;32(3):310-21.

ILAE.
ILAE Copyright Notice

Abbreviations
EEG:electroencephalography

Synonyms
Falling seizures

Major Keyword Descriptors
akinetic seizures
astatic seizures
atonia
axial muscle jerk
falling seizures
maturation phenomena
myoclonic-astatic epilepsy
myoclonus
rolandic involvement
thalamo-cortico-thalamic loop

Minor Keyword Descriptors
absences
drop attack
polygraphy
sudden falls

Age of Presentation
02-05 years

Age of Typical Presentation
02-05 years

Permutated Topics
Myoclonic-atonia seizures
atonia seizures, Myoclonic-

Related Topics
Benign myoclonic epilepsy in infancy
Dravet syndrome (severe myoclonic epilepsy in infancy)
Epilepsy
Myoclonic absences
Myoclonic-astatic epilepsy of childhood
Psychogenic seizures
West syndrome

Differential Diagnosis
other reasons for falls
clumsiness when walking
syncope
cataplexy
vestibular disorders
psychogenic seizures
other types of falling seizures
tonic seizures
myoclonic seizures
atonic seizures
partial seizures
epileptic spasms

Back to Top   |    Home