You've probably heard of meningitis and know that it has
something to do with an infection and the brain and that it generally is not a
good thing to have. You're right. And that's essentially what it is - an
infection of the brain.
The most common symptom is a headache and a stiff neck;
those affected can't tip their head forward to touch their chin to their chest.
Fever (increased body temperature caused when the body sends
out the artillery to deal with the invaders), confusion or altered consciousness,
vomiting, and an inability to tolerate light or loud noises are also symptoms.
There are two common agents that cause infection - viruses
and bacteria. And it isn't any one specific virus or bug (bug is lingo for bacteria);
a variety of each are responsible. Parasites, funguses and non-infectious
agents (like cancer, cysts and certain drugs) can also be responsible.
On the virus front, enteroviruses (responsible for a range
of diseases including polio, chronic fatigue syndrome and non-specific
illnesses where fever, headache, sore tummy, sore throat and muscle pain are
symptoms), herpes simplex 2 (genital herpes), the chicken pox and shingles virus,
mumps virus, HIV and a virus carried by rats that literally goes straight to
the head of the infected person.
In adults, the bacteria Neisseria meningitidis (also
known as meningococcus) and Streptococcus pneumoniae (also known as pneumococcus)
together cause 80% of bacterial meningitis cases.
Meningococcus live in the nose and throat of 5-15% of adults
as part of the normal flora, causing no trouble.
Pneumococcus also just hangs around and you can have it and
not be ill. It's the fellow responsible for causing pneumonia and when you're
susceptible (lowered immunity, elderly, children) then it takes advantage of
the situation to cause a range of illness from a snotty nose to a sinus infection,
middle-ear infection, pink eye to pneumonia.
It's important to diagnose what has caused the meningeal infection
because treatment needs to be specific for the organism. First treatment line
is antibiotics (for meningitis caused by bacteria) and antiviral medications
(for meningitis caused by viruses).
We're invaded by a multitude of viruses and bugs all the
time and just because you have flu or a sinus infection it doesn't mean that
you'll develop meningitis.
There are three membranes that surround and protect the
brain and spinal cord. These are called the meninges.
So looking at the three layers there's a soft,
form-fitting base layer (against the brain - capillaries penetrate this layer),
a light-weight, loose-fitting waterproof shell and a storm-weather, thick and
durable waterproof jacket (below the skull). Fluid (Cerebrospinal Fluid - CFS)
flows in the space (subarachnoid space) between the loose-fitting shell and the
base layer.
And then there's this wonderful mechanism called the
blood-brain barrier (BBB). More than 100 years ago it was found that if a blue
dye was injected into the bloodstream of an animal, if showed up in tissues of the
whole body except the brain and spinal cord.
Infectious agents have to get through the meninges or BBB
into the CFS to cause meningitis, which is an infection specifically of the
loose-fitting shell (arachnoid mater) and the form-fitting base layer (pia
mater) of these layers as well as the actual brain tissue, which become
inflammed.
With is being not-so-easy for bacteria to get into the meninges
and CFS, how do they do so?
They gain access either through the bloodstream or by direct
contact with the CSF and meninges via the nasal cavity or skin. Invasion of the
bloodstream is most common. You need to have head trauma (injury / skull
fracture) or an infection of the throat or sinuses that has made contact with
the subarachnoid space.
On Friday, while at work (she's a school teacher), the first
sign for Rika that something was wrong was that she had a really bad headache
and her vision was affected to the extent that she couldn't see properly. She
was taken straight to casualty by a colleague. The hospital sent her home
having diagnosed a sinus infection. On Friday night she was in pain and not
doing well. Richard took her back to the hospital.
I think meningitis was confirmed on Saturday (lumbar
puncture is performed to extract CSF) and treatment initiated.
And this is the key element here: sinuses are one way for
bacteria to get into the CFS.
Sinuses are air-filled spaces around the nasal cavity. There
are four of them. Many major blood vessels, supplying blood to the brain, lie
next to the sinuses - and that's how infection is transferred.
You could have a sinus infection every season and never get
meningitis. It's really a combination of factors (severe infection in just the
wrong place) that results in the conditions that lead to meningitis.
Treatment is specifically geared towards fighting the
infection (intravenous antibiotics) and probably also corticosteroids to reduce
inflammation and swelling of the meninges and resulting pressure on the brain. Sedation
is common practice.
Bacterial meningitis is a very serious illness and Rika has
a battle on her hands. Being young, fit and healthy is a big positive in her
arsenal in her fight against this infection.
No comments:
Post a Comment