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Silent, subtle, unseen:How seizures happen, why they’re hard to diagnose

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The Conversation

The dramatic and incapacitating nature of seizures is reflected in
the word itself, which derives from the Greek “to take hold” – like an
invisible force suddenly grasping someone and controlling their body.
This sense of an unknown force has driven many superstitions and
misrepresentations of seizures throughout history.

Over the past century, the public’s understanding of seizures has
been gleaned mostly from depictions in movies and television, which are
often as disturbing as they are inaccurate. While these dramatic
representations intensify visual storytelling, they frequently
perpetuate stigma and understate the complexity of seizures.

The truth is, seizures are far more varied than what you see in
popular culture. Instead, they are often subtle, silent and unseen.

As a neurologist
who focuses on the comprehensive care of people who experience
seizures, I subspecialize in the treatment of those with epilepsy. That
includes identifying and improving gaps in epilepsy care. Research shows
there are many.

Why seizures occur

A seizure is caused by sudden uncontrolled electrical activity from a group of neurons.
This hyperactivity overwhelms the brain’s normal tendency to suppress
such abnormal activity on both a cellular and network level.

Not all seizures are indicative of epilepsy. An otherwise normal
brain may experience seizures during alcohol withdrawal. Seizure-like
events may also occur with an acute decrease in blood flow, which can
cause fainting.

Seizures associated with epilepsy, on the other hand, are unprovoked and often very difficult to predict.
A broad spectrum of underlying abnormalities can all lead to the
development of epileptic seizures, including brain tumors, infections,
strokes, traumatic brain injury, autoimmune conditions, developmental
abnormalities and genetic predispositions.

Seizures are not uncommon

Approximately 1 in 10 people will experience a seizure during their lifetime. But only those with a risk of recurrent unprovoked seizures are considered to have epilepsy, which represents about 1 in 26 people

Because of the wide variety of symptoms, substantial delays to diagnosis and treatment can happen. When unrecognized and untreated, seizures worsen over time and lead to decreased quality of life, cognitive impairments, injuries, including motor vehicle accidents, and sometimes death.

The irony is, much of the suffering is unnecessary. Most people with epilepsy can be seizure-free through the use of an inexpensive medication.

Focal seizures

Regardless of the cause, focal seizures
are the most common type found in adults. This seizure type arises from
hyperactivation of a confined brain region. For instance, a seizure
arising from the left motor cortex of the brain may result in shaking of
the right arm. A seizure arising from the visual cortex may cause a
person to see flashes of light or other strange visual phenomena.

The most common brain region for focal seizures to arise is one of
the temporal lobes, of which there are two – one on either side of the
brain. These lobes serve many functions and are involved in vocal,
auditory and visual processing, as well as emotions and memory. This is
why seizures arising from these areas can lead to a variety of unusual

Frequently, focal temporal lobe seizures are relatively subtle,
particularly to witnesses. Sometimes they are comprised of purely
unusual internal sensations such as sudden intense fear, a sudden sense
of déjà vu or possibly a strong odor. Until a seizure spreads to involve
more areas of the brain, it may not cause loss of consciousness or

Because untreated seizures become more frequent and severe over time,
it is not uncommon for epilepsy to begin with these relatively subtle
focal seizures, then worsen as the seizures begin to involve more brain
tissue, and eventually progress to convulsions.

Delays in diagnosis

A patient of mine described having strange symptoms for over a decade
– symptoms he had not discussed before with me or anyone else. He
described recurrent, sudden-onset euphoric sensations, which progressed
to an inability to speak for one to two minutes. A bystander would think
he was just staring into space. Over the years, these sensations
increased in frequency. They eventually became more severe and led to
loss of consciousness.

After the patient began an anti-seizure medication regimen, the
sensations went away, and he reported improvements in both memory and
cognition. Fortunately, he did not experience physical injury, or worse,
before his evaluation. But many people are not so lucky.

Recent studies have confirmed that delays in diagnosis are common
among people who have epilepsy. Undoubtedly, this is because the early
subtle and unusual symptoms are not well recognized by patients,
families or medical professionals.

A revealing study

The Human Epilepsy Project
is a large, multinational prospective study that followed nearly 500
people with newly treated focal epilepsy for five years. I was among the
researchers who analyzed the study’s data, and we found a striking
diagnostic delay among many participants. Many of them experienced
seizures for several months or even several years before diagnosis.

From those first seizures to the diagnosis, half the participants
experienced injuries; 5% had car accidents attributable to seizures.
Extrapolating this data to the general population suggests that every
year in the U.S., over 1,800 motor vehicle accidents are due to undiagnosed subtle focal seizures. With a timely diagnosis, these accidents are potentially preventable.

However, even those evaluated for seizures don’t always receive the
correct diagnosis or treatment. Nearly two-thirds of those participating
in the Human Epilepsy Project sought an initial seizure evaluation in
an emergency department. About 90% were there only after their first
convulsive seizure – that is, after the seizure spread and now involved
the full brain.

But leading up to that first convulsive seizure, nearly half of
participants had been experiencing nonmotor focal seizures, which went
largely unrecognized. For that reason, many people who could have been
diagnosed with epilepsy and started on treatment were not.

As it stands now, about 200,000 U.S. adults seek evaluation at a hospital’s emergency department
for a first lifetime seizure every year. Often, they are diagnosed with
epilepsy at that time or shortly thereafter. Poor recognition of subtle
seizures bears significant consequences for individuals, communities
and the health care system. Improving our understanding of the diverse
ways seizures arise and affect lives will help us close the gap and
lessen the consequences.

Jacob Pellinen is an Assistant Professor of Neurology, University of Colorado Anschutz Medical Campus.

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