Types of seizures
Epileptic seizures in brain tumour patients
Epileptic seizures as symptoms of a cerebral tumour disease are generally focal seizures as they emanate from a localized nidus (lat. “focus”), the brain tissue around the tumour. They can occur as simple-focal seizures or as at the beginning focal, secondary generalized grand mal seizures with loss of consciousness.
Simple-focal seizures are e.g. motoric convulsions or tingling in a limb, taste or odour perceptions or an odd feeling in the pit of the stomach. All these focal symptoms can induce a spread of the epileptic activity in the brain and result in a complex-focal or even a generalized seizure.
Complex-focal seizures occur mainly in localisations of the tumour in the temporal lobe. These seizures often have a typical clinical appearance: Affected patients can sense an odd feeling in the abdominal region (epigastric aura), an odour perception (olfactory aura) or vegetative symptoms (e.g. tachycardia). Then munch, swallow or masticatory movements (oral automatisms) can appear.
Occasionally affected people perform stereotypic, recurring, unreasonable actions and show an insufficient or lacking responsiveness to environmental cues while doing so. For the complex-focal seizures often exists an at least partial memory lapse, during the seizure the environment is experienced as familiar or strange, the sense of time can be altered. These are signs of a disturbance of consciousness. However the seizures do not result in a loss of consciousness.
In brain tumour patients also episodic states may appear which can involve confusion, inadequate reactions to the environment, slowed down thinking processes and course of actions and obviously nonsensical actions. In such episodic “semi consciousnesses” it is always necessary to think of the state of complex-focal seizures. Here it is about the continuous sequence of complex-focal seizures which are difficult to diagnostically estimate for a not clinically trained person.
Such a non-convulsive (not crampy) state resp. sorted semi consciousness is often triggered by a tumour in the temporal lobe. The only possibility to diagnose such a state of complex-focal seizures is the EEG. In an EEG-registration at this state epilepsy-characteristic potentials appear in the electrocardiogram which originate in the affected temporal lobe.
When the neuroelectric activity of a focal seizure spreads into the whole brain this can lead to a so called secondary generalized seizure (grand mal). This manifests itself as rhythmic convulsions of arms and legs. The patient is unconscious during the seizure and hence does neither perceive the grand mal itself nor can remember it later in most cases. A seizure usually lasts only a few minutes, afterwards the patient recovers consciousness, often in a for the time being confused state. Frequently he drifts off to a deep night’s sleep, which can last from only a few minutes up to several hours.
If the seizures lasts significantly longer without the patient becoming conscious in the meantime then a grand mal state could exist, this means a series of generalized seizures. That condition can become life-threatening and must be put in charge of an emergency physician.
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