Epilepsy - B. Pharma 2nd Semester Pathophysiology notes pdf





       Status epilepticus



At the end of PDF Notes, student will be able to

         Define epilepsy

         Define status epilepticus

         Classify epilepsy

        Describe the pathogenesis of epilepsy


       Chronic brain disease of diverse etiology

       Characterized by recurrent paroxysmal episodes of uncontrolled excitation of brain neurons

        Manifesting as brief episodes (seizures) of loss of consciousness, with or without characteristic body movements (convulsions)

Status epilepticus (SE)

Continuous convulsion lasting longer than 30 minutes OR Occurrence of serial convulsions between which there is no return of consciousness

Pathophysiology of Epilepsy

       Normally, a balance between excitatory and inhibitory factors - proper functioning of a healthy human brain

       Reduction of inhibitory synaptic activity or enhancement of excitatory synaptic activity -trigger a seizure

        NTs mediating the bulk of synaptic transmission in the mammalian brain are amino acids

       GABA - principal inhibitory

       Glutamate - excitatory neurotransmitters

       Repeated epileptic discharge can cause neuronal death (excitotoxicity).

        A relative deficiency of inhibitory neurotransmitters such as GABA

        An increase in excitatory neurotransmitters such as glutamate would promote abnormal neuronal activity

Clinical manifestations of Epilepsy

       Depend on the location of the focus and the pathways involved in its spread

       ‘Generalised’ - initial activation of both hemispheres of the brain

       ‘Partial’ or ‘Focal’ -  discharge starts in a localised area of the brain

Grandmal seizure

       Generalized convulsion, also called the grand-mal seizure.

       Patient loses consciousness and usually collapses.

       Followed by generalized body stiffening (called the "tonic" phase of the seizure) for 30 to 60 seconds,

       violent jerking (the "clonic" phase) for 30 to 60 seconds,

       patient goes into a deep sleep.

       During grand-mal seizures, injuries and accidents may occur,

       Tongue biting and urinary incontinence

Absence seizures

       Short loss of consciousness (just a few seconds) with few or no symptoms

       Patient, most often a child

       Seizures begin and end abruptly

       Patients are usually not aware that they are having a seizure, except that they may be aware of "losing time."

Myoclonic seizures

       Consist of sporadic jerks

       Usually on both sides of the body

       Patients sometimes describe the jerks as brief electrical shocks

        When violent, these seizures may result in dropping or involuntarily throwing objects

Clonic seizures

·         Repetitive

·         Rhythmic jerks

·         Involve both sides of the body at the same time

Tonic seizures

Tonic seizures are characterized by stiffening of the muscles.

Atonic seizures

       Sudden and general loss of muscle tone

       Particularly in the arms and legs

       Often results in a fall

Simple partial seizures

       Key feature is preservation of consciousness

        A sudden depolarization within a group of neurons called Paroxysmal depolarizing shift (pds)

       Lasts for 200 ms occurs in case of patients with partial seizures.

       This results in generation of an abnormally rapid train of action potentials

Complex partial seizure

       Impaired consciousness lasting 30 seconds to 2 minutes

       Often associated with purposeless movements such as lip smacking or hand wringing

       Associated with amnesia

Secondarily generalized seizure

Ø  Partial seizures may get generalized

Ø  spreading along diffuse connections to involve both cerebral hemispheres

Ø   This seizure spread occurs through several pathways

ü   U FIBRES connect various regions of the cortex.

ü   CORPUS CALLOSUM allows for spread between hemispheres.

ü   THALAMOCORTICAL PROJECTIONS provide a pathway for diffused synchronized spread throughout the brain


       Epilepsy is characterized by recurrent paroxysmal episodes of uncontrolled excitation of brain neurons

        Manifesting as brief episodes (seizures) of loss of consciousness, with or without characteristic body movements (convulsions)

       Continuous convulsion lasting longer than 30 minutes is status epilepticus

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