Theophylline neurotoxicity resulting in significant unilateral brain-damage

Theophylline-associated seizures and their clinical characterizations

BACKGROUND

To elucidate the basic mechanism of theophylline-associated seizures (TAS), the clinical symptoms, electroencephalogram (EEG) and neuroradiological imaging of eight pediatric patients were all retrospectively evaluated.

METHODS

Patients whose seizures represented their first episode were selected, while patients with cerebrospinal fluid abnormalities including pleocytosis and protein elevation, present illness of head trauma, epilepsy, febrile convulsion or any psychomotor retardation were excluded although they were given theophylline.

RESULTS

Eight patients, 3.5 +/- 1.7 years of age, thus fulfilled the definition of TAS in the past 5 years. Based on their seizure patterns, EEG findings, brain single-photon emission computed tomography and head magnetic resonance imaging, a total of seven of eight patients had either localized or unilateral dominant lesions. They all had fever, > or =38 degrees C, and six of eight patients had a family history of febrile convulsions and/or idiopathic epilepsy. Thereafter none of them had convulsions after the cessation of theophylline administration. Through the TAS event, a 6-year-old female patient was found to have a right deep lateral cerebral venous angioma.

CONCLUSION

In infants with idiopathic low seizure threshold and fever, theophylline administration might possibly trigger a seizure. Moreover, based on these patients' clinical findings, some kind of cerebral vascular involvements is speculated to be related with TAS.

Permeability of the developing and mature blood-brain barriers to theophylline in rats

1. In the present study, the uptake of theophylline and L-glucose into the adult and neonatal rat brain has been investigated. Steady state cerebrospinal fluid (CSF) and brain concentrations of theophylline were reached within 1 h following a single intraperitoneal (i.p.) injection, whereas steady state CSF and brain concentrations of L-glucose were not approached until after 5 h. 2. Steady state brain:plasma and CSF:plasma concentration ratios for theophylline and L-glucose in neonatal rats were significantly higher than ratios in adult rats. Erythrocyte:plasma ratios for theophylline in neonatal rats were also significantly higher than ratios in adult rats. Steady state ratios for theophylline were significantly higher than those for L-glucose in both neonatal and adult rats. 3. Respiratory acidosis (pH 6.9-7.0) did not affect steady state CSF:plasma or brain:plasma ratios for theophylline in neonatal or adult rats. In contrast, steady state CSF:plasma and brain:plasma ratios for L-glucose were increased by respiratory acidosis. 4. The lower steady state CSF:plasma, brain:plasma and erythrocyte:plasma ratios for theophylline in adult rats are likely to be due to a higher concentration of plasma proteins in adult blood compared with neonates, with a greater retention of protein-bound (non-exchangeable) theophylline in adult blood, and are unlikely to be due to p-glycoprotein-mediated efflux of theophylline at the adult blood-brain barrier.

Unilateral brain damage after prolonged hemiconvulsions in the elderly associated with theophylline administration

The brains of 14 elderly patients who died after status epilepticus were examined pathologically. Three of the 14 patients showed unilateral brain damage which corresponded to the side of the seizures, and the lesions were thought to be caused by seizures. In these three and two other patients, no causative lesion related to the seizures was found. In these five patients, status epilepticus occurred during theophylline therapy and thus the seizures in these five patients were assumed to be induced by theophylline. In the three patients with unilateral brain damage, the damage was seen in the hippocampus, amygdala and thalamus in two patients, while in the third, the whole hemisphere was damaged, including the hippocampus, amygdala, thalamus, basal ganglia and cerebral cortex. The distribution of pathological changes within the thalamus was described. It is suggested that the thalamus was primarily affected by seizures, rather than by secondary degeneration from the cortex.

Methylxanthines: toxicity to humans. 1. Theophylline

While there are several comprehensive reviews on the toxic effects of theophylline, caffeine and theobromine in animals, data on the toxicity of these methylxanthines in humans have not been extensively reviewed in one document. This question will be addressed in a series of three papers. This paper provides an overview of the human toxicity of theophylline. Only pertinent and recent information on theophylline toxicity is summarized. In addition, some information regarding the use and benefits of theophylline, the mechanism of its effects and factors that affect variability in its clearance and half-life is also provided. Some problems in the analytical methodology of theophylline, problems that may be responsible for the controversy in the reported dose-response effects, are critically reviewed.