Hematologic disorders can produce a wide range of neurologic disturbances. When seizures arise because of hematologic dysfunction, the diagnosis of seizure activity is, for the most part, no different than its diagnosis in isolation. The challenges of treatment are often far more complex, however, as the drugs used to control seizures may affect the underlying condition or interact with medications used to treat it. In general, the medical treatment of choice should be the one that can, if at all possible, be administered as a single agent with minimal side effects or interactions and with maximal efficacy.
Seizures may arise from systemic disorders in a number of ways. One of the most frequent is when a particular body system has been sufficiently impaired to produce a lowering of the seizure threshold and the induction of “reactive seizures.” In this situation, the problem is largely that of identifying the toxic or metabolic disorder triggering the seizures and addressing this cause. Once function has been normalized, there is usually little need for future seizure prophylaxis with antiepileptic drugs (AEDs).
A second scenario is when the underlying condition (or some other disorder) has created an enduring state of cortical neuronal instability, such as a stroke with infarction, hemorrhage, or embolus. The focal lesion itself may then trigger seizures spontaneously, or may do so after a relatively minor systemic insult. The lowering of seizure threshold from this insult might not have triggered a seizure had a structural abnormality not been present.
Finally, a number of toxic or metabolic disturbances arising from body system failures may impair mental status and induce an encephalopathy. Here, the question may arise as to whether the patient, instead of having partial seizures, is in nonconvulsive status or postictal state. Confusion in encephalopathy may be further complicated by the appearance of adventitious movements easily mistaken for ictal events. The movements may arise as a function of the confused state or, more pertinently, may result from an adventitious movement disorder, such as tremor or myoclonus. In these situations, in which there is an increased clinical suspicion of seizures, the electroencephalogram (EEG) is increasingly essential to establishing a diagnosis of seizures.
Adapted from: Sepkuty JP and Kaplan PW. Hematologic and pulmonary disorders. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;209–228.
With permission from Elsevier (www.elsevier.com).