Tonic-clonic Convulsions

Primary generalized seizures are also heterogeneous with respect to their clinical features. Such seizures can impose as absence epilepsy, which is characterized by a brief interruption of consciousness due to highly synchronized neuronal activity involving thalamocortical networks without increases in neuronal firing rate. On the other hand, tonic-clonic convulsions with loss of consciousness are often also primarily generalized. 

Tonic-clonic convulsions are abnormal motor behavior during a seizure characterized by slow movements with high muscle tension (tonic phase) and subsequent repetitive oscillating movements of limbs (clonic phase). 

Evidence of neurotoxicity was also observed in animal studies. Nose-only exposure of rats to endosulfan at concentrations of 3.6 mg/m in females and 12.3 mg/m in males resulted in trembling and ataxia (Hoechst 1983a). At higher concentrations in both sexes, tremors, tonic-clonic convulsions, and reduced corneal, pupillary, placing, shock, paw-pinch, and cutaneous reflexes were observed. Nose-only exposure of male and female rats to concentrations of endosulfan of up to 2 mg/m for 6 hours/day,... 

The effects of protein deficiency on endosulfan toxicity were studied in Wistar rats (Boyd and Dobos 1969 Boyd et al. 1970). Rats fed a diet totally deficient in protein for 28 days prior to administration of a single oral dose of endosulfan had an LDjq of 5.1 mg/kg of endosulfan. Rats fed a low-protein diet (3.5% protein) for 28 days had an LDjq of 24 mg/kg of endosulfan. Rats fed standard laboratory chow (26% protein) had an LDjq of 102-121 mg/kg. The immediate cause of death in all animals was respiratory failure following tonic-clonic convulsions. This study demonstrated that, while a protein-deficient diet does not affect the nature of the toxic reaction, it may affect the sensitivity of rats to the lethal effects of endosulfan. 

Similarly, convulsive seizures and a sustained epileptic state persisted after stomach contents were pumped and activated charcoal and anticonvulsive medication were administered in a 43-year-old man who ingested approximately 260 mg/kg endosulfan (Boereboom et al. 1998). At 4 days after exposure, the man was pronounced brain dead, and autopsy revealed cerebral hernia from massive cerebral edema. Eight additional accidental and/or intentional cases of acute poisoning with endosulfan resulting in adverse neurological effects have been reported in more recent studies, six by Blanco-Coronado et al. (1992), one by Lo et al. (1995), and one by Pradhan et al. (1997) two out of the eight resulted in death. Tonic-clonic convulsions were seen in the Blanco-Coronado et al. (1992) cases, whereas Lo et al. (1995) reported the development of muscle fasciculations and episodes of convulsions in their case. In the case reported by Pradhan et al. (1997), the patient had consumed about 75 mL of hquid endosulfan (35% w/v). In this case, in addition to tonic-clonic seizures and myoclonic jerks, the patient developed... 

Central nervous system stimulation is the hallmark of acute overexposure to endosulfan in experimental animals. The spectrum of effects includes hyperexcitability, tremors, decreased respiration, tonic-clonic convulsions, and ultimately, death (Boyd and Dobos 1969 Boyd et al. 1970 Ceron et al. 1995 FMC 1958,1959a, 1980a Gilbert and Mack 1995 Hoechst 1970, 1975, 1984e Kiranand Varma 1988 ... 

Signs of acute endosulfan intoxication in animals are similar to those seen in humans and include hyperexcitability, dyspnea, decreased respiration, fine tremor, and tonic-clonic convulsions. Oral LDso values range from 7.4 mg/kg in male mice to 40-125mg/kg for... 

All local anesthetics have the ability to produce sleepiness, light-headedness, visual and auditory disturbances, and restlessness when high plasma concentrations are produced after rapid absorption or inadvertent intravascular administration. An early symptom of local anesthetic toxicity is circumoral and tongue numbness and a metallic taste. At higher concentrations, nystagmus and muscular twitching occur, followed by tonic-clonic convulsions. Local anesthetics... 

Withdrawal of the aromatic substituent in 1-aroxysilatranes from the oxygen atom in a methylene group leads to a sufficient decrease in toxicity (LDS0 of 1-benzyloxysilatrane is 2250 mg/kg). Whereas administration of 150 mg/kg of 1-phenoxysilatrane to white mice produces tonic-clonic convulsions, 1-benzyloxy-silatranes administered at higher doses only cause slight hyperemia. 

A 23-year-old pregnant woman developed antepartum bleeding at 35 weeks and a tonic-clonic convulsion and hypothermia at 39 weeks, having used heroin 4 hours before. She had further tonic-clonic seizures, became obtunded, and required intubation. She had occasional runs of ventricular bigeminy. A cesarean section was performed. The neonate had poor respiratory effort and required ventilation. Blood chemistry suggested inappropriate secretion of antidiuretic hormone, acute renal insufficiency, and acute pancreatitis. She and the baby recovered after 2 weeks. 

An overdosage of local anesthetics can produce dose-dependent central nervous system (CNS) side effects such as insomnia, visual and auditory disturbances, nystagmus, shivering, tonic-clonic convulsions, and finally fatal CNS depression. The initial CNS excitation and convulsions may be brought under control by diazepam or thiopental. 

Chloroquine can cause seizures in patients with epilepsy. The mechanism is uncertain, but it may include reductions in inhibitory neurotransmitters and pharmacokinetic interactions that alter anticonvulsant concentrations. Tonic-clonic convulsions were reported in four patients in whom chloroquine was part of a prophylactic regimen. Antiepileptic treatment was required to control the seizures. None had further seizures after withdrawal of the antimalarial drugs (9). 

A 36-year-old man had two generalized tonic-clonic convulsions after receiving intrathecal tetracaine 8 mg to supplement inadequate block estabhshed by intrathecal administration of tetracaine 10 mg (205). His seizures were controlled with intravenous thiamylal sodium. He regained consciousness, but complained of dizziness and blurred vision. He had a sensory block to T4—5. 

A 22-year-old man had a generalized tonic-clonic convulsion and loss of consciousness after an attempted superior laryngeal nerve block using 2% lidocaine 2 ml (282). The seizure was not terminated by intravenous diazepam 10 mg and he was intubated after intravenous thiopental and suxamethonium. He required two boluses of ephedrine 10 mg to maintain... 

A 75-year-old woman received ropivacaine 160 mg intravenously through an epidural catheter (10). After completion of the injection, she suddenly became unresponsive and had a generalized tonic-clonic convulsion accompanied by a sinus tachycardia of 120/minute but no other cardiac dysrhythmias. 

Accidental administration of 10 doses of smallpox vaccine to an already vaccinated girl resulted in a clinical picture characterized by neuraxitis with general tonic-clonic convulsions. Complete cure was attained after treatment with hyperimmune antivaccinia globulins and methisazone (38). 

An 8-year-old girl with leukemia had tonic-clonic convulsions and life-threatening encephalopathy after intravenous vincristine. After the second dose (1.5 mg/m in combination with prednisone) she developed seizures and bilateral translucencies in the CT scan. When vincristine was withdrawn in subsequent cycles, the symptoms disappeared (61). 

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