Epilepsy

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Epilepsy\: a neurological condition with recurrent epileptic seizures due to aberrant electrical activity in the brain, a
over 600,000 people in the UK.
Pathophysiology\: imbalance between excitatory (glutamatergic) and inhibitory (GABAergic) neuronal signalling at the
synaptic level, reducing the threshold for neurotransmission.
Risk factors\: head injury, stroke, brain tumours, neurodegenerative diseases, genetic syndromes (e.g., tuberous sclerosis,
Dravet syndrome), metabolic/electrolyte imbalances (e.g., hyponatraemia, hypoglycaemia), CNS infection (e.g.,
encephalitis, meningitis), and alcohol withdrawal.
Seizure classi
Focal onset\: aware or impaired awareness, motor (e.g., automatisms, atonic, clonic) or nonmotor (e.g., autonomic,
behavioural arrest).
Generalised onset\: motor (e.g., tonic-clonic, myoclonic) or nonmotor (absence seizures).
Unknown onset\: motor (e.g., tonic-clonic) or nonmotor (behavioural arrest).
Clinical features\: seizures with initial prodrome, stereotyped semiology (e.g., head deviation, limb jerking), post-ictal
confusion or disorientation. Post-ictal limb weakness (Todd’s paresis) can occur.
Di
Investigations\:
Bedside\: basic observations (vital signs), capillary blood glucose.
Laboratory\: FBC, U&Es, bone pro
Imaging\: CT/MRI head to identify predisposing factors.
Electrical\: EEG, video-telemetry, patient videos.
Diagnosis\: requires two or more unprovoked seizures more than 24 hours apart or a diagnosis of an epilepsy syndrome.
Management\:
Medical\: anti-seizure medications (e.g., sodium valproate, lamotrigine), rescue medications (e.g., buccal midazolam).
Dietary\: ketogenic diet for rare epilepsy subtypes.
Surgical\: resection of epileptogenic focus, lobectomy, hemispherectomy, or corpus callosotomy for refractory seizures.
Complications\: accidental self-injury, status epilepticus, sudden death in epilepsy (SUDEP).
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Introduction

Epilepsy is a neurological condition in which patients experience recurrent epileptic seizures.
During a seizure, synchronised aberrant electrical activity originating from a speci
This most commonly manifests with motor or sensory symptoms and is often (but not always) associated with reduced
consciousness levels.
It is estimated that over 600,000 people in the UK are living with epilepsy.
1Aetiology
Pathophysiology
Epileptic seizures result from an imbalance between excitatory (glutamatergic) and inhibitory (GABAergic) neuronal
signalling at the synaptic level, resulting in a reduced threshold for neurotransmission.
Anatomy
The clinical signs of a seizure (semiology) vary depending on where it begins in the brain (the seizure focus) and where it
spreads.
For example, seizures a
cycling) and vocalisation. In contrast, seizures a
sensations (e.g. deja vu), and those involving the occipital lobe are associated with simple visual disturbance.

Risk factors

Structural abnormalities
Structural abnormalities in the brain a
seizures. Examples include\:
Head injury
Stroke
Space-occupying lesions (e.g. brain tumours)
Neurodegenerative diseases
These can also occur as part of a genetic syndrome such as tuberous sclerosis or neuro
Neurochemical imbalance
A neurochemical imbalance may also make neurons more likely to
conduction can also cause epilepsy. For example, in Dravet syndrome, a mutation a
channels involved in neuronal conduction causes epileptic seizures.
Seizure threshold
The threshold for seizure activity in all patients, including those with epilepsy, may be lowered by metabolic or electrolyte
abnormalities (e.g. hyponatraemia, hypoglycaemia), central nervous system infection (e.g. encephalitis, meningitis) or
alcohol withdrawal. Seizures secondary to one of these conditions are often called provoked seizures.
For some patients with epilepsy, seizures can be induced by environmental factors, such as
this is rare.

Clinical features

Classi
The International League Against Epilepsy classi
onset, or unknown onset (Table 1). In all of these categories, seizures may be either motor or non-motor.
2
Focal seizures begin from a speci
awareness may be impaired. These seizures may have motor or nonmotor onset. Focal seizures may spread to the
contralateral hemisphere to become a generalised seizure (secondary generalisation).
Generalised seizures a
characteristic abnormal movements\:
Tonic-clonic\: sti
Myoclonic\: jerking movements
Atonic (a.k.a drop attack)\: sudden loss of muscle toneAbsence seizures (a.k.a generalised non-motor seizures)\: a type of generalised seizure characterised by a brief vacant
period where the individual is unresponsive, but muscle tone is not usually a
Table 1. The classi
Focal onset Generalised onset Unknown onset
Aware
O f s e l f a n d
Impaired
e n v i r o n m e n t ;
awareness
f o r m e r l y
k n o w n a s
O f s e l f a n d
e n v i r o n m e n t
s i m p l e p a r t i a l
s e i z u r e
Motor onset
Automatisms – repeated
stereotyped movements
Atonic
Clonic
Epileptic spasms
Hyperkinetic
Myoclonic
Tonic
Nonmotor onset
Autonomic
Behaviour arrest
Cognitive*
Emotional**
Sensory
Motor onset
Tonic-clonic
Other motor
Nonmotor onset
Absence
Motor onset
Tonic-clonic
Epileptic spasms
Nonmotor onset
Behaviour arrest
Unclassi
“ D u e t o i n a d e q u a t e
i n f o r m a t i o n o r i n a b i l i t y t o
p l a c e i n o t h e r c a t e g o r i e s .
”
*either negative features (e.g. impaired language), or positive features such as déjà vu, hallucinations, illusions, or
perceptual distortions
**e.g. anxiety, fear, joy, or change in a
History
Most patients who experience a seizure cannot give a history of the event. It is invaluable to gain a collateral seizure
history from an eyewitness.
Key features of an epileptic seizure to establish from the history include\:
Prodrome\: initial prodrome before seizure onset may involve a sensory aura such as a rising abdominal sensation.
The seizure itself\: usually a period of reduced consciousness with stereotyped semiology (e.g. head deviation and limb
jerking); individuals may experience tongue biting, incontinence, automatisms, abnormal speech, laughing or crying.
Post-ictal period\: the termination of a seizure is followed by the post-ictal period, whereby individuals are likely to be
confused or disorientated. This can last for hours or even days.
For more information, see the Geeky Medics guide to seizure history taking.
Clinical examination
During a seizure, patients are often unresponsive. Depending on the type of seizure, muscle tone may be increased or
decreased.
Post-ictal limb weakness (Todd’s paresis) may occur following a seizure. This can last from a few hours to days. Between
seizure episodes, the neurological examination is usually normal, or clinical signs may re
syndrome (e.g. tuberous sclerosis).Di
Di
Dissociative seizures (functional seizures or non-epileptic attacks)\: a type of functional neurological disorder (FND).
Functional seizures often have distinctive diagnostic features and a lack of abnormal electrical activity in the brain during
an event. Features of functional seizures include long duration of the seizure (compared to epileptic seizures, which
usually last \<90 seconds), quick recovery, retained awareness with bilateral arm movements, back arching, eye-opening
during events and a sensation of detachment from reality (dissociation).
Vasovagal episodes\: prodrome of dizziness followed by loss of consciousness; in some cases, jerking movements may
be seen during a vasovagal faint but are very brief, and patients recover quickly without a postictal period.

Investigations

Bedside investigations
Relevant bedside investigations include\:
Basic observations (vital signs)\: to identify hypoxia and haemodynamic instability
Capillary blood glucose\: to identify hypoglycaemia, an important reversible cause of seizures
Laboratory investigations
Relevant laboratory investigations include\:
Full blood count\: neutrophil cell count may also often be raised after a generalised seizure
Urea & electrolytes\: to identify reversible causes (uraemia, hyponatraemia)
Bone pro\: to identify hypercalcaemia
Venous blood gas\: due to prolonged muscle contraction, lactate is raised following a tonic-clonic seizure (although it
can also be raised in prolonged functional seizures)
Imaging investigations
Neuroimaging (CT/MRI head) is used to identify any underlying predisposing factors such as previous stroke or tuberous
sclerosis. For most patients with epilepsy, neuroimaging is normal.
Electrical and visual recordings
Relevant investigations include\:
Electroencephalogram (EEG)\: large numbers of electrodes are placed on the patient's head to detect electrical activity
and identify patterns suggestive of a seizure
Video-telemetry (VT)\: video recordings combined with EEG recordings are made over several days of monitoring to
capture and characterise seizure semiology
Patient videos\: given the widespread usage of smartphones, patients and family members can
these with clinicians

Diagnosis

To be diagnosed with epilepsy, patients should have experienced two or more unprovoked seizures more than 24 hours
apart or have been diagnosed with an epilepsy syndrome. Experiencing a single seizure is usually insu
diagnosis of epilepsy.

Management

The goal of epilepsy management is to reduce the frequency of seizures as much as possible with minimal side e
For more information on managing a seizure, see the Geeky Medics guide to the emergency management of seizures.
Patient education and emotional support are essential due to the risks associated with epileptic seizures and the
restrictions this imposes on daily life. For more information, see the Geeky Medics guide to epilepsy counselling.Medical management
Epilepsy is managed with daily anti-seizure medications, primarily targeting sodium channels or modulation of
GABAergic neurotransmission (examples include sodium valproate or lamotrigine).
Patients are usually also o
seizure that does not self-terminate within
Ketogenic diet
The ketogenic diet is a high-fat-low-carbohydrate diet, which has been found to reduce seizure frequency for some
rare epilepsy subtypes by altering the brain’s metabolism. This is a challenging diet to adhere to, and bene
therefore often limited.
Surgical management
Patients experiencing debilitating seizures refractory to medications may be o
obstruct neurotransmission. This may involve resection of either the epileptogenic focus, a lobe of the brain or, in rare
cases, an entire hemisphere. Alternatively, surgical division of the corpus callosum (corpus callosotomy) can be performed.

Complications

Complications of epilepsy include\:
Accidental self-injury such as super
the local environment may occur during a seizure
Status epilepticus is de
intervening return to consciousness over a
require general anaesthesia if unresponsive to
Sudden death in epilepsy (SUDEP) is when a person diagnosed with epilepsy (most commonly tonic-clonic seizures)
dies unexpectedly, and no other cause is established; this usually occurs during the night and is unwitnessed.

References

Epilepsy Research. E p i l e p s y s t a t i s t i c s . Available from\: [LINK]
International League Against Epilepsy (ILAE). I L A E 2 0 1 7 C l a s s i LINK]

Reviewer

Dr Neil Ramsay
Neurology registrar

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Contents

Introduction
Aetiology
Risk factors
Clinical features
Di
Investigations
Source\: geekymedics.com