29
April 2014
0715
hrs
So,
Patient Reader, I suppose you noticed that case history up there somewhere, put
in like the non-sequitur that it sort
of is . . . I think it’ll come into play
a little later if you continue to be patient . . . which of course, you will be.
I tried
mixing up the staff notes to include a lot of medical jargon as well as try to
eliminate some confusing abbreviations so that the layman can follow
along. Anyway, thanks for getting it.
OK, so
. . . back to the rant. Shall I continue? Splendid!
The
Cunning Fennec Fox
Posterior
to the pre-frontal cortex, about halfway around the head and just
above the ears, lie the temporal lobes. It
is here that lie the regions that govern speech and language, among other
things. Much of memory is stored here,
if I remember correctly.
90% of
us store our language centers in the left hemisphere; the other roughly 10%
store them on the right.
Broca’s
area, a neuronal bundle about the size of a 50 cent piece- remember those? Controls
the mechanics of speech. It rules our
sibilants and our plosives, and smoothly softens out our curiously pointed
diphthongs. This region is just behind
and above our temples.
Wernicke’s area,
subtler and more abstract in its function, lies above and behind, generally
speaking, the pinnae of our
ears. This is the region, approximately
the size of a stick of gum, where we build the engines of our words that Broca
will drive.
Here we
construct our sentences using the grammar we learned in school; the sounds to
which we have been exposed within our environment beginning in utero.
The
babblings we noise out as infants and early toddlers are Broca and Wernicke
learning to work together, having been unable to warble with amniotic fluid
filling our lungs.
We may
not know from whence our feelings of “love” originate, but we say it, express
it, apprehensively and in vain hopes, from these regions first.
Neuroscience
has determined in recent years, primarily through functional MRI (fMRI) that,
just between Wernicke and Broca the words as signals are screened through our
primary visual cortex, found tucked away in our occipital lobes at the backs of
our heads. It seems we “see” what it is
we are about to say.
This phenomenon is
found, surprisingly and yet not, as we humans tend to have similar wiring
across the board to one another, in those blind from birth. We would not have discovered this without
fMRI.
The
blind, it would seem, see as well as the sighted. And it is in this case that “Sight” is as
indefinable as “Love.” (A side note worth
mentioning is that we have seen people victorious in say, sports or other
competitive activity, raise their arms in a “V” and puff out their chests. Interestingly, people blind from birth also
do this. Why is it that this behavior is
hard-wired into our neuronal structure?)
Other
parts of our neo-cortices contain the aforementioned visual cortex, as well as
the sensory and motor strips, lying posterior and anterior to the Rolandic
Fissures of our brains, respectively. All
of the neuronal tissue found here and in our spinal cords make up the central
nervous system (CNS).
The
grey matter that is neurons however, must have a scaffolding upon which to
build.
White
matter, the brain’s lattice-work, is composed primarily of astrocytes and glial
cells; cells that support and lend nourishment and some protection to the
fragile neurons.
The
vascular neo-cortex is susceptible to strokes, both thrombotic (clot-related)
and hemorrhagic (aneurysm-related).
White matter
however, being composed mostly of quite different cellular matter than that of
grey matter, is at much higher risk of tumors.
Abnormal
growths, such as scar tissue and as-yet-unidentified tumors are most commonly
referred to as “lesions,” a term that wields a fairly large umbrella that
encompasses many forms. It is when they
are identified as pre-cancerous or cancerous that they are called tumors.
In a
closed environment (such as the cranium) these growths incur an adjective: space-occupying.
As they grow, these tumors, having nowhere else to
go, press against structures that, due to increasing insult, affect how these
structures command the systems they supposedly govern.
Most
often, these tumors present with seizure activity. If the lesion is say, in the part of the
brain that governs motor control on the left side, seizures will present
there. If large enough, there can be
secondary generalization, that is to say the seizure can cross the corpus callosum connecting the left and
right hemispheres and then the paroxysm becomes global.
As the
term suggests, global means that it involves the entire cortex. Playing music is a global process, for
example.
Not all
seizures are caused in this way; this is merely an example as it relates to
growths within the brain.
The space-occupying astrocytes
and glial cells are susceptible to mutations of this type of lesion.
Astrocytomae are usually benign and
encapsulated cysts. Comparatively easy
to remove, they tend to be the best-case scenario for neurologists and
neurosurgeons. Oh, and patients, also.
Gliomae
and glioblastoma multiforme are quite different. These differentiated cells tend to form un-encapsulated
growths and send out tendrils like snaking tentacles into surrounding
tissues. They are aggressive; they grow
rapidly and indiscriminately. They
reroute blood supply in a process known as angiogenesis;
that is to say, they grow their own blood vessels. They strangle everything in their paths much
like an invasive weed growing unchecked.
Glioblastomae are the Kudzu of Neuropathology.
They
grow until they kill. They can and do
send out mutated cells that set up shop in other substations; they relocate to
breast, to bone . . . to lung . . .
Sometimes the reverse is true:
cervical cancer can metastasize to bone and breast and brain. Cancer blows.
As we
marvel at the brain’s plasticity, we sometimes see that insulted tissue’s
counterpart in the opposite hemisphere sit up and take notice. If seizures go unchecked, this healthy tissue
“learns” and decides that such paroxysmal activity is normal. Soon we have epileptiform discharges
originating from perfectly healthy brain tissue. This is known as a “mirror focus.”
Miranda
had a glioblastoma multiforme. Miranda
was developing mirror foci.
If this
were detected soon enough, caught before the choking tendrils were dispatched
to reconnoiter and colonize, these malignant intruders may be operable and
cause minimal damage.
This
was, naively, our greatest hope.
More to follow; this rant ain't over yet!
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