EPILEPSY

EPILEPSY

It can be defined as a condition characterized by recurrent unprovoked seizures. A seizure is a sudden involuntary alteration in perception or behaviour caused by an abnormal synchronized discharge of cortical neurons in the central nervous system. An attack of seizure can be defined as epilepsy only when it has a recurrent tendency to occur. At least two unprovoked seizures are required for the diagnosis of epilepsy.

Generally the seizures are classified into Partial and Generalized.

Partial Seizures

Partial seizures begin focally in a restricted focus of cerebral cortex in contrast to generalized seizure types.

1. Simple Partial Seizure: Consciousness and ability to interact with external environment are not impaired. It can be: (a) with motor signs, (b) with somato-sensory or special sensory symptoms, (c) with autonomic symptoms or signs, or (d) with psychic symptoms.
2. Complex Partial Seizure: Consciousness is impaired. Patient is unable to respond normally to external stimuli because of altered awareness. It can be: (a) Simple partial onset followed by impairment of consciousness, or (b) with impairment of consciousness at onset.
3. Secondary Generalized Partial Seizures: Consciousness is impaired and tonic–clonic (convulsions) movements occur. It can be: (a) Simple partial seizures evolving to generalized seizures, (b) Complex partial seizures evolving to generalized seizures, or (c) Simple partial seizures evolving to complex partial seizures and complex partial seizures then evolving to generalized seizures.

Generalized Seizures

In generalized seizures, there is a diffuse disturbance of cortical function and seizures begin more or less simultaneously in both the cerebral hemispheres. Usually consciousness is impaired and motor manifestations are usually bilateral and synchronous. There are six types of generalized seizures.

1.       Tonic-clonic Seizures: Similar in behaviour to secondarily generalized seizures, but they begin without an aura or complex partial seizures and the tonic or clonic movements are symmetric.

2.      Absence Seizures: Two type: –Typical and Atypical. Typical absence seizures are characterized by lapses of consciousness (absence) that rarely last longer than 10 seconds. A typical absence seizure almost always produce motor signs especially changes in tone. They last for more than one 10 sec. and are usually followed by postictal confusion.

3.       Myoclonic Seizures: Myoclonus is a sudden involuntary, brief, shock like muscle contraction that can result from epileptic and non-epileptic mechanisms. Myoclonic seizures of cortical origin are unilateral or bilateral synchronous jerks than can be single or repeated arrhythmically succession. It can occur both in primary and secondarily generalized epilepsies and are a defining feature of juvenile myoclonic epilepsy. These seizures have no postictal state.

4.       Clonic Seizures: These are essentially tonic clonic seizures without the tonic component. These seizures are followed by postictal confusion.

5.       Tonic Seizures: These are characterized by tonic spasms of truncal and facial muscles with associated flexion or extension of extremities and impairment of consciousness. They usually last 5 to 20 sec.

6.      Atonic Seizures: Atonic seizures consist of a sudden loss of tone in postural muscles. Usually they are lasting for less than 5 sec. Although they are associated with the change of consciousness, there are no noticeable postictal changes. When they are mild and restricted to some muscles only, they may cause a brief head drop but when severe, they lead to sudden collapse and fall.

 Diagnosis

1.      History: The history is obtained from the patient and the witnesses is the most important information in establishing the diagnosis of seizure disorder (describe in detail the events before, during and after the seizure).To determine the cause of a seizure, it should know that whether there is a family history of epilepsy, personal history of head trauma, birth complications, febrile convulsions, middle ear or sinus infections, alcohol or drug abuse or symptoms of cancer.

2.      Physical Examinations: Signs of head trauma, infection of the ear or sinuses (which may spread to the brain), any neurocutaneous markers (tuberous sclerosis) or evidence of systemic malignancy.

3.      Laboratory Tests: Blood sugar, serum calcium estimation, serum electrolytes and liver function tests in adults, electroencephalography (EEG) in the waking and sleeping states, Computed Tomography (CT), and Magnetic Resonance Imaging (MRI).

Psychiatric Consequences of Epilepsy

Short-term Effects

1.      Preictal disturbances: Irritability, depression, fearfulness and apathy.

2.   Periictal disturbances: Aura, weird indescribable feelings, epigastric sensations, fear, feelings of unreality, illusions and hallucinations in all sensory modalities, deja’ vu and jamais vu phenomenon, forced thinking and alterations of consciousness.

3.      Postictal disturbances: Postictal confusion and disorientation and transient psychotic symptoms like hallucinations (auditory) and delusions (persecutory) occur in many cases. Sometimes the postictal psychosis continues for several weeks and in some patients it becomes fixed and fails to resolve. In others it is transitory or short lasting for one and two days only.

Long-term effects

1.      Cognitive disturbances: Impaired attention, concentration and memory.

2.      Personality changes: Aggression, alteration of sexuality, elation, depression, lability of mood, deepening of emotions, hypergraphia, obsession, paranoid symptoms, philosophical and religious interest and viscous speech.

3.      Psychotic disturbances: Schizophrenia, serious depressive symptoms and bipolar mood disorder.

4.      Neurotic disorders: Anxiety disorder, mood disturbances and dissociative disorders.