Induction of spinal seizures by natural stimulation in cats

Possible causes of seizure after spine surgery

Seizure after laminectomy for spinal procedure is very rare and has not been reported after lipomyelomeningocele surgery beforehand. Here, two cases of seizure following laminectomy for lipomyelomeningocele are reported. The exact etiology of the event is unknown but anesthetic material, pneumocephalus, intracranial hypotension subsequent to cerebrospinal fluid leakage after spinal procedures, spinal-induced seizure and the potential toxic effect of fat molecules could be considered.

Right-sided vagus nerve stimulation inhibits induced spinal cord seizures

We have previously shown that left-sided vagus nerve stimulation results in cessation of induced spinal cord seizures. To test our hypothesis that right-sided vagus nerve stimulation will also abort seizure activity, we have initiated seizures in the spinal cord and then performed right-sided vagus nerve stimulation in an animal model. Four pigs were anesthetized and placed in the lateral position and a small laminectomy performed in the lumbar region. Topical penicillin, a known epileptogenic drug to the cerebral cortex and spinal cord, was next applied to the dorsal surface of the exposed cord. With the exception of the control animal, once seizure activity was discernible via motor convulsion or increased electrical activity, the right vagus nerve previously isolated in the neck was stimulated. Following multiple stimulations of the vagus nerve and with seizure activity confirmed, the cord was transected in the midthoracic region and vagus nerve stimulation performed. Right-sided vagus nerve stimulation resulted in cessation of spinal cord seizure activity in all animals. Transection of the spinal cord superior to the site of seizure induction resulted in the ineffectiveness of vagus nerve stimulation in causing cessation of seizure activity in all study animals. As with left-sided vagus nerve stimulation, right-sided vagus nerve stimulation results in cessation of induced spinal cord seizures. Additionally, the effects of right-sided vagus nerve stimulation on induced spinal cord seizures involve descending spinal pathways. These data may aid in the development of alternative mechanisms for electrical stimulation for patients with medically intractable seizures and add to our knowledge regarding the mechanism for seizure cessation following peripheral nerve stimulation.

Vagus nerve stimulation for induced spinal cord seizures: insights into seizure cessation

OBJECT

Vagus nerve stimulation is known to decrease the frequency, duration, and intensity of some types of intracranial seizures in both humans and animals. Although many theories abound concerning the mechanism for this action, the true cause remains speculative. To potentially elucidate a pathway in which vagus nerve stimulation aborts seizure activity, seizures were initiated not in the cerebral cortex but in the spinal cord and then vagus nerve stimulation was performed.

METHODS

Ten pigs were anesthetized and placed in the lateral position, and a small laminectomy was performed in the lumbar region. Topical penicillin, a known epileptogenic drug to the cerebral cortex and spinal cord, was applied to the dorsal surface of the exposed cord. With the exception of two animals that were used as controls, once seizure activity was discernible via motor convulsion or increased electrical activity the left vagus nerve, which had been previously isolated in the neck, was stimulated. Following multiple stimulations of the vagus nerve and with seizure activity confirmed, the cord was transected in the midthoracic region and vagus nerve stimulation was performed. Vagus nerve stimulation resulted in cessation of spinal cord seizure activity in all (87.5%) but one experimented animal. Transection of the spinal cord superior to the site of seizure induction resulted in the ineffectiveness of vagus nerve stimulation to cause cessation of seizure activity in all study animals.

CONCLUSIONS

The effects of vagus nerve stimulation on induced spinal cord seizures involve descending spinal pathways. The authors believe that this experiment is the first to demonstrate that spinal cord neuronal hyperactivity can be suppressed by stimulation of a cranial nerve. These data may aid in the development of alternative mechanisms for electrical stimulation in patients with medically intractable seizures. Further studies are now necessary to isolate which specific tracts, nuclei, and neurotransmitters are involved in this process.

Spinal cord seizures: a possible cause of isolated myoclonic activity in traumatic spinal cord injury: case report

Spinal cord seizures are infrequently reported. They have been associated with intravenous dye placement, transverse myelitis and multiple sclerosis, but never with traumatic spinal cord injury (SCI). We report the case of a 48-year-old SCI male with complete C6 quadriplegia, and apparent spinal cord seizures. These seizures were characterised by myoclonus simplex activity involving the upper extremities only. The lower extremities were spared. The patient was conscious throughout the myoclonic activity and an electroencephalogram of the brain obtained during an event revealed no cortical epiliptiform activity. The seizures lasted approximately 30 seconds to a few minutes, and an acute increase in blood pressure and a decrease in pulse generally occurred 30 to 60 seconds prior to the event. Previously reported spinal cord seizures in multiple sclerosis were frequently treated with carbamazepine. In this case successful treatment was with diazepam. Spinal cord seizures may present in those with traumatic SCI. Benzodiazepines may be useful in the treatment of spinal cord seizures.

Cisplatin-induced neurotoxicity with seizures in frogs

Cis-diamminedichloroplatinum II (cisplatin) given by injection to adult frogs (Rana pipiens) resulted in tonic-clonic seizures 3 to 5 weeks later. The seizures could be induced multiple times; the animals appeared entirely normal between seizures. In the spinal cord there was vacuolation in the anterior grey horns. Ultrastructurally, the vacuoles consisted of swollen astrocytic processes in the neuropil and around neurons. Generalized edema with swelling of perivascular astrocyte foot processes was not seen. Systemic administration of cisplatin to frogs results in neurotoxicity with seizures and astrocytic swelling in the spinal cord.