A focal seizure is a sudden surge of electrical activity from a single area inside the brain resulting in muscle contractions and behavioral changes.
Focal seizures are epileptic seizures starting from one side of the brain. They are also known as partial seizures since the entire brain is not taking part in the seizure activity. A seizure happens when a group of nerve cells in the brain sets out a burst of electrical impulses at the same time. This results in abnormal responses from one’s body parts, muscle groups, level of consciousness, and behavioral patterns. Like every other type of seizure, focal seizures can be controlled by appropriate treatment.
The brain controls and regulates the body’s functions by sending out electrical signals known as action potentials to the concerned part of the body. The brain cells, called neurons, communicate with each other with the help of electrical charges and chemicals known as neurotransmitters. When an area of the brain malfunctions due to some reason, the nerve cells tend to behave abnormally by sending out sudden bursts of electrical signals. And the body responds to this by symptoms like passing out, involuntary muscle contractions, and altered senses. The underlying cause of a focal seizure may be:
Infections in the brain like meningitis or encephalitis.
Traumatic head injuries.
High blood pressure or low blood sugar.
Structural defects in the brain by birth.
A stroke, liver failure, or kidney failure.
Alcohol and substance abuse.
Withdrawal from alcohol or drugs.
Certain neurological diseases tend to cause seizures.
Based on one’s level of awareness during the seizure activity, focal seizures are divided into two types. They are:
Focal Aware Seizures - Where one does not lose consciousness and stays fully aware of what is happening around them. Only the affected individual cannot voluntarily make any body movement or create a response even if they want to. This condition is also referred to as a simple partial seizure. Such an attack may last for a few seconds to two minutes. Sometimes a focal seizure itself may be presented as an aura before a full-scale seizure attack sets in. An aura is a set of warning signs one may experience before going into the actual seizure.
Focal Impaired Awareness Seizure - It is also known as a complex partial seizure. Here the individual loses the time-place person awareness at the time of a seizure attack. And usually, it may last for one to two minutes.
Based on what area of the brain is malfunctioning, individuals experience a variety of symptoms in focal seizures. Symptoms could be mild to severe as well. Let us look at the way seizures originating from each area of the brain present themselves:
A Frontal Lobe Seizure:
Usually occurs during sleep and may get mistaken for a sleep disorder or a psychiatric illness.
A single group of muscles in the body tends to stiffen, twitch, or jerk. Occasionally these movements may spread to other areas too.
Legs are thrashing, kicking, or pedaling uncontrollably.
Pelvic thrusting and rocking movements of the body.
Tend to lose bladder control.
One may laugh, scream or swear during a seizure attack.
An Occipital Lobe Seizure:
Characteristic eye movements, which are uncontrollable and rapid. One may flutter the eyelids, blink the eyes, roll them to one side or keep moving from side to side.
Go partially or fully blind at the time of seizure.
Tend to see colors, patterns, and flashing lights in front of the eyes. One may even see nonexistent pictures of animals, scenery, or people.
A Parietal Lobe Seizure:
One may feel an electric shock-like sensation spreading over an area of the body, like pinpricks or insect crawling.
The affected part of the body may feel pain, numbness, tingling, burn, or cold.
Hallucinations about seeing the nonexistent. Things appear smaller or larger than they are.
Strange feelings such as a body part gone missing, shrunk, enlarged, moving away, or floating.
Unable to comprehend the language or perform simple calculations, writing, or reading.
A Temporal Lobe Seizure:
The individual may be aware of the surroundings at the start of the attack but gradually turn unaware.
A strong sense of deja vu, experiencing a strange taste and smell, and hearing imaginary noises.
Unknown fears set in; show changes in heart rate.
Nausea and a queasy feeling in the stomach.
Tend to behave strangely. One might start to walk around, runoff, keep fidgeting or start to undress, smack the lips, and do repeated chewing and swallowing movements with the jaws.
At the end of the seizure attack, one stays confused and unable to speak for a while.
After a focal seizure attack, most people recover fast and go back to whatever they are doing without feeling any discomfort. Some may tend to feel confused, exhausted, and sleepy for some time. Occasionally an individual may suffer from an inability to move the affected body part after the seizure attack. This condition is called Todd’s paralysis and lasts for about a few minutes to thirty-six hours till recovery.
As each type of focal seizure varies with symptoms, the doctor will listen to one's experience at the start, during, and after a seizure attack. The onlookers can also contribute to the symptoms by describing what they witnessed while the individual suffered an attack. Based on the medical history and the symptom, the doctor may run the following tests:
An electroencephalogram (EEG) - Electrodes are attached to one’s scalp, and the electrical activity of the brain is recorded by an output device to identify the pattern and area of electrical malfunction in the brain. This helps in understanding from where inside the brain the seizures originate.
Imaging studies such as computed tomography scans (CT) or magnetic resonance imaging (MRI) identify the underlying conditions such as tumors or damaged areas.
Blood tests or lumbar puncture (spinal tap) to look for inflammation, infection, or bleeding inside the head.
Treatment focuses on controlling the intensity and frequency of seizure attacks. For this, the initial step is to treat the underlying cause of the seizure. In the majority of cases, seizures are effectively controlled with medications. One may prescribe:
Antiepileptic medications such as; Lamotrigine, Levetiracetam, Topiramate, Valproate, Zonisamide, Carbamazepine, Oxcarbazepine, Phenytoin, Lacosamide, etc.
A vagus nerve stimulation is where the electrical activity of the brain is controlled by attaching an electrical stimulator to the neck.
Rarely may one require surgical removal of the malfunctioning area of the brain.
Adopting ketogenic diet plans (low in starches, high in fat) have been seen to help with focal seizures.
In most cases, individuals undergoing a focal aware seizure do not require any help from those around them during an attack. But a person suffering from focal impaired awareness seizure needs help to stay safe and avoid dangers from falls and other scenarios. One may prevent seizure attacks to an extent by avoiding the triggers and making lifestyle modifications. Periodic medical follow-up is mandatory for better results.
Last reviewed at:
28 Sep 2022 - 5 min read
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