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  Diagnosis

(Choose one)

Based on:

1. Clinical features

2. Patterns on EEG

3. History of Patient

4. Physical Examinations

5. Laboratory Data

6. Differential Diagnosis

 

 

An epilepsy syndrome diagnosis are required for crucial outcomes to determine:

 

 

1.      Clinical features

Seizures can be hard to diagnose because clinical features (during a seizure) constitutes one of the main deciding factors in establishing a seizure occurrence and of the type of epilepsy a person has. Most seizures do not happen while a doctor is around, so inevitably the doctor will ask you or the witnesses* over and over again to describe what exactly happened.

How you can help:

·    Best to obtain an account from a firsthand witness a description of the behaviors during seizure. You might want to tape down the seizures using a video camera when possible. This would allow the neurologist to actually see the seizures, and made a better diagnosis out of it.

·        Try your best to give as much details as possible including events experienced before and after the seizure, when it occurs and any unusual behaviors involved.

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*Read about what are the appropriate things to do during a seizure.  

 

 

 

2.      Patterns on EEG  

·        What is it?

      An EEG (electroencephalography), which is the study of electrical activity in the brain, is used to confirm the presence of epilepsy and diagnosis of the seizure type whether it is generalized or focal abnormalities.

·        How is it done                                                                                             

     First the patient lies down, a number of small electrodes are placed over the scalp over different regions of the head. The electrode will carry information about the brain's electrical activity to the amplifier. A special machine records the amplified brain's waves and produces pattern of tracings called electroencephalogram. During recording, the patient may be asked to breathe deeply or looked at a flashing light. 

     Patterns formed in EEG are useful in identifying the type of seizures. However EEG can only gives results during the test period whereas seizures can occur anytime and occasionally. A normal EEG results does not imply normal brain function but possibly requirement for 24 hours monitoring in the hospital. Seizures happen in the deep part of the brain is hard to see on an EEG as well.

     Several options are available to increase the registration of seizure activity by an EEG. Often, a strobe light is used. To increase the likelihood for EEG to show the abnormal pattern, a patient may not be allowed to sleep the night before an EEG is to be taken. This is done to reduce the threshold for seizures to occur which is usually the case when a person gets very tire.

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3.      Medical, Non-medical and family history

     

      a. Family History. Risk of developing epilepsy in family is higher in idiopathic (of unknown causes) generalized seizures than in partial seizures. However the genetic mechanisms remain unclear. If a person develops idiopathic epilepsy before the age of 15, the risk of a sibling also developing epilepsy is about 5% compared to that of the cumulative risk of 1.7% for the general population. The risk is higher(6-12%) if a person's parent also has epilepsy and/or the results from EEG said so. The overall risk of offspring is 2.4 - 4.3%. Certain types of seizures are also associated with a higher possibility of inheritance. To date, twelve forms of epilepsy have been demonstrated to possess some genetic basis. Febrile seizure and LaFora Disease are two examples. LaFora Disease (a progressive myoclonic seizure) is a particularly aggressive epilepsy thought to result from a mutation in the gene which is thought to produce laforin - a protein that help maintain a balance of sugars in the blood stream. Too much laforin may destroy brain cells, which may then lead to the development of LaFora Disease.

 

       b. Age of onset. Certain types of epilepsies are age-specific. Vasovagal syncope and pycogenic non-epiletic seizures are most commonly first present in adolescents and young adults. After age of 25, founding of an idiopathic (no known cause) generalized epilepsy becomes rare. On the other hand, partial seizure can occur at any age and the incidences  increases after age of 65, commonly due to stroke.

 

       c. Sleep deprivation. Can be a potent stimulus for seizures in epileptic patients but can also cause occasional isolated seizures.

 

       d. Visual stimuli. Photic stimulation with flickering lights, including electronic screens, tend to trigger the commonest reflex type of epilepsies. Other possible stimuli include complex patterns such as computer games or reading. Some patients may derive pleasure or stimulation from the induction of seizures with photic stimulation. The photosensitivity diminishes with age: 10% of patients presenting with seizures between the age of 7 and 19 years are reported to have photosensitivity. 

 

       e. Drug abuse. Seizures related to alcohol abuse, in particularly with alcohol withdrawal are common. Other drug- induced epileptic seizures are rare, but the wide variety of drugs reported to precipitate or potentate seizures include aminophylline, amitriptyline, amphetamine, anticholinergics, benztropine, bronchodilators, cephazolin, chlorpromazine, cocaine, heroin, insulins, isoniazid, lignocaine, loxapine, meperidine, narcotic analgesics, penicillin, pentazocine perphenazine, phencyclidine, prochlorperazine, psychotropic agents, stimulants and thioridazine. 

 

      f. Medical history . After a head injury, if seizures occur within a week, risk of developing epilepsy later is 25% overall and 33% over the age of 16. Immediate seizures after injury are not associated with epilepsy. Otherwise, if early seizures have not occurred, severe blood clots and depressed skull fractured tend to associated with higher risk of late epilepsy at 31% and 15% respectively. The risk of developing chronic epilepsy after febrile seizure is 2-7%. Patients with low sugar level, low salt level and low calcium level in blood are also more likely to develop seizures.  

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4.      Physical and neurological examinations  

 

Brain imaging is often recommended but their choice depend on cost, availability and affordability. Often, MRI is preferred. They includes:

 

      a. CAT or CT scan known as computerized axial tomography, gives 3D-computer images of brain. CT scanning will identify a focal abnormalities in selected patients presenting with partial and generalised tonic-clonic seizures and a handful of patients with no focal abnormalities on neurological examination and EEG. A significant proportion of abnormalities identified by CT scanning may be treatable by surgery. However, CT scanning may fail to show a focal abnormality in a significant proportion of patients with focally abnormal neurological signs.

 

     b. MRI (Magnetic Resonance Images) - give better defined 3D structure of the brain and is indicated in patients with intractable epilepsy. MRI of the brain detects abnormalities that are not detected by CT scanning. The number of such lesions detected has increased as the quality of magnetic resonance images has improved, and is dependent on the sophistication of the MRI techniques employed. A significant proportion of patients with these lesions can potentially be treated with surgery. 

 

     c. MRS (Magnnetic Resonance Spectroscopy) - provides function about brain's functioning and biochemistry.  

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5.      Clinical laboratory data

     Depending on the differential diagnosis, other investigations such as blood glucose, urea, electrolytes e.g. sodium and chloride, liver function tests and serum calcium may be indicated.

 

      Based on 1. and 2., a doctor can establish and then classify a seizure to a particular category. Once epilepsy is confirmed (on the second or third seizure), the doctor will be most interested in trying to find its cause. Data obtains from 3, 4, and 5 can possibly pinpoint a cause and rule out any other medical conditions with symptoms easily mistaken as epilepsy.

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6. Differential Diagnosis

       The disorders that most commonly need to be distinguished from epileptic seizures are vasovagal syncope, psychogenic non- epileptic attacks and anxiety attacks. 

 

Vasovagal syncope

      Often patients presented to a hospital A & E department, as a result of  sudden loss of consciousness, is commonly due to vasovagal syncope (40%) rather  than epilepsy (29%). It is particularly the case when there has been a potential trigger, such as fear, pain, sudden standing from squatting or lying posture and cough. Movements, sensory and autonomic features may look like seizures. Myoclonic jerks lasting less than 10 seconds, head turning, automatisms (lip smacking, chewing), upward rolling of the eyes, vocalization and sensory symptoms, including visual hallucinations and even out- of- body experiences, and uncontrolled urination may occur in syncope. Although there may be a transient throbbing headache and involuntary urinating after syncope, the convulsive features of syncope are not followed by any after-effects such as fatigue, or confusion as observed in seizures.

 

Psychogenic non- epileptic attacks/ Pseudo-seizure/ Hysterical seizures

     Many patients with a firm diagnosis of ‘epilepsy’ have non- epileptic attacks. The predisposing factors for non-epileptic attacks are female sex, previous childhood sexual abuse, a previous psychiatric history, sexual maladjustment, current depression and morbid anxiety. Psychogenic non- epileptic attacks may be classified by the following presentations:

         Injury and incontinence may occur in psychogenic non- epileptic attacks. Out-of-phase  limb movements, head turning from one side to the other, and forward pelvic thrusting and other bizarre limb and trunk movements can occur in partial epileptic seizures (particularly in those arising from the frontal lobe), as well as in psychogenic non- epileptic seizures. 

       Features suggestive of psychogenic non- epileptic seizures are resistance to eye opening in an otherwise unresponsive patient and aversion of the eyes away from the examiner when the lids are elevated. Recurrent episodes of collapse with prolonged unresponsiveness lasting more than a few minutes are most often due to psychogenic non- epileptic seizures, and not due to uncomplicated syncope. Other possibilities that should be considered include complex partial status epilepticus (an emergency) and low blood sugar. 

 

Other disorders which may require consideration are listed here.

 

 

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