Clonic seizures are irregular short-term spasms characterized by a rapid change of periods of contraction and relaxation of skeletal muscles. They occur against the background of epilepsy, cerebral damage of an infectious, neurodegenerative, toxic or other nature. The cause of convulsive paroxysms is confirmed by laboratory tests, genetic tests, neuroimaging methods, EEG. The basis of therapeutic correction is the use of anticonvulsants, resistant options require a solution to the issue of neurosurgical care.
Causes of clonic seizures
Isolated clonic seizures are more common in focal forms of genoine (idiopathic) epilepsy. The attack occurs due to abnormal excessive activity of neuronal structures. The epileptic focus of partial paroxysms is limited to separate areas of the brain, and the generalized attack becomes with the rapid propagation of the excitation wave to both hemispheres.
Partial seizures are often observed in frontal epilepsy, combined with head turns, dystonic brush installation, hypermotor automatism. Complex focal seizures with loss of consciousness and secondary generalized paroxysms with lesions of the frontal lobes are found much less frequently. Before clonic spasms, a number of patients develop a somatosensory aura of the type of paresthesia throughout the body.
The basis of myoclonic epilepsy of infancy (Dravet syndrome) is encephalopathy with polymorphic seizures. In children under one year of age, pathology begins with febrile paroxysms with a focal component, disrupts mental development. After 3-5 years, hemiclonic seizures appear, changing the side of the lesion even during one attack. Myoclonic paroxysms are considered an important sign of the disease, gradually increasing in intensity and frequency.
Seizures are accompanied by some infections of early childhood. Their occurrence is caused by nonspecific encephalopathic reactions, which are based on swelling and swelling of the brain, diapedesis hemorrhages. Even minor organic changes in the central nervous system, allergization contribute to the development of seizures. Short-term hypoxia of the brain on the background of coughing is explained by seizures with whooping cough.
Clonic seizures are often present in the clinical picture of SARS – influenza, parainfluenza, adenovirus infection. Seizures can be determined at the beginning of the disease, at the height of rashes during the peak period (with measles, chickenpox) or as a delayed complication. Seizures occur without precursors and last 2-3 minutes, are easily stopped. Frequent seizures pose a threat to the formation of an epileptic focus.
Diffuse gray matter lesion
Clonic seizures occur with diffuse lesions of the gray matter of the brain. Creutzfeldt-Jakob disease has a prion nature, and subacute sclerosing encephalitis is a slow infection caused by the measles virus. In the first case, a rapidly progressive dementia, ataxia is detected. Later, clonic spasms occur, provoked by a loud sound or other stimuli.
The course of subacute sclerosing encephalitis has a number of similar signs. At first, mental disorders increase, the emotional sphere suffers. Then motor disorders are joined in the form of convulsive twitching of individual muscles, hyperkinesis, atactic syndrome. Vision is impaired up to blindness, spastic paresis, urinary incontinence are noted. The disease is characterized by high mortality.
Clonic paroxysms and mental retardation manifest other diseases. The lysosomal accumulation disease, Tay-Sachs disease, has a neurodegenerative character. It develops against the background of a genetic breakdown of the enzyme that utilizes gangliosides in the central nervous system. The pathology is characterized by convulsive twitching, developing into epiprimes, rapid progression of visual and hearing impairments, and mental retardation.
A similar inheritance (by autosomal recessive type) has the Alpers-Huttenlocher syndrome, in which a mutation of the gene encoding mitochondrial DNA polymerase is observed. The disease is manifested by convulsive syndrome, blindness, progressive dementia. Pathology can begin with coordination disorders, liver failure is typical in the later stages. Focal clonic seizures are insensitive to therapy, sometimes they take a status course.
The genesis of convulsive syndrome in non-progressive encephalopathies (tuberous sclerosis, Down syndrome) is unknown. Diseases are accompanied by mental retardation, hypotension, myoclonus. The latter are combined with partial, generalized or unilateral clonic seizures. The most common types of paroxysms in children with tuberous sclerosis are infantile spasms, which often turn out to be insensitive to anticonvulsants.
Convulsive syndrome can be considered as a non-specific response of the still immature newborn brain to the effects of adverse factors. Familial and idiopathic neonatal seizures (“seizures of the fifth day”) have a benign character. The first are inherited according to the autosomal dominant principle, arise mainly in a dream. Short clonic seizures are combined with apnea, oral automatism, ocular symptoms.
The appearance of idiopathic neonatal seizures is associated with zinc deficiency. They are detected in full-term newborns in the form of a single episode of multifocal or focal paroxysms lasting from 2 hours to 3 days. Clonic seizures may be accompanied by short-term apnea and cyanosis, and do not affect the development of the child. They are resistant to drugs, but they pass on their own, they no longer repeat.
Clonic seizures manifest toxic lesions of the central and peripheral nervous system caused by chemical compounds. Toxic substances affect motor neurons of the motor pathways or neuromuscular synapses, disrupting the balance of neurotransmitters and electrolytes inside cells, which provokes the generation of excitatory impulses. The cause of seizures are various intoxications and poisoning:
- Medications: piperazines, ergotamine, opioid analgesics.
- Toxic substances: phenol and aniline, formaldehyde, arsenic.
- Household chemicals: pesticides (organochlorine compounds), insecticides.
- Plants: belladonna, aconite, chilibukha, ergot.
- Mushrooms: fly agarics.
Sometimes it is possible to assume the cause of clonic seizures clinically – according to anamnesis and neurological examination. At the same time, pay attention to the time and circumstances of the development of the attack, its nature, the presence of concomitant symptoms. But in most cases, an accurate diagnosis is made based on the results of additional procedures:
- Laboratory tests. In case of infections, microscopy and sowing of biomaterial (nasopharyngeal mucus, sputum, liquor) are prescribed, serological tests, DNA or RNA of the pathogen are detected by PCR. Children with accumulation diseases undergo enzyme diagnostics, toxicological analysis is shown for poisoning.
- DNA diagnostics. Verification of hereditary diseases is carried out by cytogenetic study of the karyotype, analysis of a panel of genes or individual mutations. The risk of developing pathology in the fetus can be established by prenatal testing.
- Neuroimaging. Structural defects are detected by tomography. In cases of diffuse lesions of brain tissue, signs of encephalopathy (hyperintensive foci in the cortex, cerebellum or trunk), atrophy are visible on MRI. CT scan of the brain indicates scattered calcifications in tuberous sclerosis.
- Electroencephalography. Epileptic and non-epileptic paroxysms are indications for EEG. The study allows us to establish the localization of convulsive activity (focal, multifocal, generalized), its morphology (waves, peaks, “runs”), frequency and other characteristics.
In the diagnosis, the neurologist is assisted by related specialists. A characteristic sign of Tay-Sachs disease – a red spot on the retina – is determined by an optometrist during ophthalmoscopy, hereditary pathology requires the involvement of a geneticist. It is necessary to differentiate clonic seizures with paroxysmal states of a different genesis: stereotypical movements, syncopal states, pseudo-seizures.
Help before diagnosis
Severe and prolonged seizures require mandatory medical intervention. With generalized clonic seizures, before the arrival of the ambulance team, the patient is laid on a flat surface with a pillow under his head, the restraining clothes are unbuttoned, and free air access is provided. It is not recommended to resist involuntary movements. The remaining paroxysm is stopped by the introduction of anticonvulsants.
Treatment of clonic seizures is largely symptomatic, aimed at alleviating the patient’s condition by reducing the frequency and severity of seizures. Etiotropic and pathogenetic therapy for most of the described diseases has not been developed, so the emphasis is on supportive treatment. Depending on the clinical situation, medications of the following groups are used:
- Anticonvulsants. The drugs of choice for the treatment of focal seizures are valproates, carbamazepine, lamotrigine (but the latter two are contraindicated in Dravet syndrome). Neonatal seizures are treated with phenobarbital, phenytoin, benzodiazepines.
- Neurometabolic. In neurodegenerative processes, antioxidants and B vitamins are prescribed as part of complex therapy. Nootropics and vasoactive drugs are contraindicated for many patients due to their ability to provoke seizures.
- Antimicrobial. Etiotropic treatment of infectious diseases consists in the use of antiviral, antibacterial agents. This approach is also practiced in subacute sclerosing encephalitis (immunoglobulin, interferon, isoprinosine).
- Detoxification. Toxic damage to the central nervous system requires infusion therapy, the introduction of sorbents, specific antidotes. In severe cases, extracorporeal detoxification methods (plasmapheresis, hemosorption, hemodialysis) are used.
Complex therapy of the underlying disease involves the use of physical methods – electrical muscle stimulation, massage, therapeutic gymnastics. Neuropsychological rehabilitation plays an important role in cognitive disorders. A promising area of treatment of hereditary diseases is targeted gene therapy, the possibilities of which are still being studied.
Drug-resistant clonic seizures are sometimes treated neurosurgically. In children and adults, cortical and subpial resections of epileptogenic foci, functional hemispherectomy, dissociating operations are practiced. This leads to a reduction in the number of seizures and a rapid improvement in the quality of life. The development of tumor-like formations in persons suffering from tuberous sclerosis requires consideration of the feasibility of adjuvant radiotherapy.