Terminology & Reality:
It is difficult to discuss this subject without first having yet another snit about customary medical terminology. The official categorization of neurologic injury which is deeply ingrained
into medical "codes" (computer classifications for insurers) is based on the ability to count to four. So, if a person with neurologic injury has only one limb impaired that
is monoplegia; two limbs impaired, diplegia; three limbs is tri
plegia. Four is quadriplegia. Four limbs with body and head is total body.
But what USEFUL information does that convey? This classification is worse than useless. It is annoying.
Aside from the fact that the limbs are not the site of injury but just taking orders as sent, the terminology
homogenizes many causes. Imagine if we only had the word tree for that collection of upright plants. So much for ash, elm, oak, maple, catalpa, evergreen, spruce, balsam, birch, tulip, aspen, fir, cypress, juniper, larch, tamarack, pine, cedar, beech,
chestnut, eucalyptus, hickory, walnut, sycamore, ailanthus, magnolia, olive, fig, ficus, plane, palm, willow, locust, sequoia, redwood, poplar, acacia, cottonwood, beech, box elder,
apple, crabapple, redbud, mulberry, cherry, peach, plum, pear, prune, banyan, baobab, bamboo, abba, calabra, betel, mahogany, ebony, bo, ironwood, dogwood, ginko, bottle, or bonsai,
burned, worm ridden, moss covered or whatever.
Mono, di, tri, quad. That's it? Working clinicians have morphed this insisted (encysted?) terminology into a more useful -
though confusing - shorthand code which, hopefully, goes unnoticed by administrators, in order that it serve a more useful purpose - treatment.
For treatment we need descriptions based on the presumptive neurologic types and shapes of brain injury as it affects
capability. From that, we can infer approximate resultant functional consequences.
So, diplegia ("two limbs weak") has come to mean that which results from tiny
speckled white infarcts (or small hemorrhages) scattered just outside the periphery of the ventricles of the brain ( whether two limbs are involved or not ). In microscopist
lingo that description becomes periventricular leukomalacia (PVL). Peri= around,
ventricular=relative to ventricles (fluid cysterns in the brain), leuko = white or clear colored, malacia= oooy gooey or mush, or pathologically "soft".
The premature brain has a network of extra blood vessels that deliver blood to the
brain surface or cortex. That is protective of the cortex when flow pressure drops for any reason. The lease served area for extra flow is adjacent the ventricles as that is a
fluid region devoid of solid structures. Adjacent the ventricles (periventricular) is bay side property. When the winds of trouble blow in the preemie, the bay side property
gets hit most.
When PVL speckled damage is confined to a small region, manifestation of
malfunction may well be in the legs only. Perhaps, just the ankles. Maybe just a trace of ankle reflex sensitivity not even noticed clinically at all. Typical PVL can be one
sided in which case the diplegia is really only one leg ( hemi-diplegia ).
As the scope of these small PVL injuries scatters further out in a larger radius into
the periventricular brain suburbs, hands and arms may also be involved somewhat. Even so, we still don't call it quadriplegia. The peculiar pattern and quality of
muscular usage is what is important. PVL or "diplegia" conveys that. So diplegia - forget that di means two - may well have four limbs involved. The dominant
manifestation is legs AND in a certain way.
There is a unique quality to the way diplegia function is impaired. Lately, even
parents are referring to their children as having PVL. Good
. That tosses out the old misleading nomenclature. I like that. PVL is a very common neurologic complication
in preemies. One third of all CP is prematurity related and thus have the PVL type of neurologic based involvement.
The classic look of diplegia (PVL) is inward rotation crouch. The typical functional
limitation is via speed related recruitment of unasked for muscular activation (speed related recruitment of additional muscle activity is called spasticity. Anything else
which is called spasticity is called that WRONGLY!!!!) It is an important distinction. Kids with high levels of spasticity may have their control mechanisms intact, but,
overloaded with extraneous stuff. Sensory mechanisms are usually working.
Remember that prematurity is itself a complication of something else. There can be
incompetent cervix or twin / triplet issues. But prematurity may brought on by genetic problems within the child's genome causing late spontaneous abortion. The
earlier the prematurity, the more likely an underlying embryologic or fetal cause is also present.
Nit picking? No. Don't get blinded by statistics. Statistics do not cause. They report.
You can simply report that last year 0.001% of the population got run
down by trucks (I made that number up) - and/or
- you can advise that folks don't stand in highways. Percent relatedness of CP to prematurity is a batting average. The idea is to avoid being a statistic. Look to causation. Maybe the first truck just brushed you, but a bigger wider one is bearing down? Turns out that of the 0.001% who are hit by trucks, 80% are run over by six more following cars. Ouch. That's the point. When brushed by a truck, don't stand there giving the trucker the finger. Move!
Fortunately, outside the ventricles the brain has a superhighway of up and down
going motor and sensory pathways made mostly of cell projections (and not the cell bodies themselves. Conduits. The motor lanes that involve the legs are most central.
As you go from the feet upward, neurologic input paths layer on top and thus are further from center. Geometry figures in diplegia. The range of severity in diplegia
correlates with the concentric layering on of motor pathways as you travel up the spinal cord and to the brain past the ventricles. Closest to the ventricles are the
projections from the foot and ankle. Furthest away are those from the neck. So, just foot involvement means a small radius of damage. Hand or neck involvement implies
a large radius of damage which may well overlap other kinds structures. Other kinds, closest are the basal ganglia (wherein damage can generate rigidness and / or dystonic
types of inappropriate muscular signals (described below).
Quadriplegia & Ataxia:
Quadriplegia, on the other hand, is what is seen after diffuse anoxic (no O2) brain
injury. The pattern of brain involvement reflects damage where ever the brain's metabolic rate most demands oxygen and also where tissues are most easily damaged
by concomitant CO2 build up (which makes acid).
The really important stuff, the basic richly cellular deeper brain base regions are
highly metabolic and thus sensitive to oxygen deprivation and CO2 excess. This is true in adults as well as children.
Carbon monoxide poisoning, for example, disables hemoglobin such that oxygen can't
get delivered by the red blood cells. Those basal brain structures which use much oxygen get damaged first. These cells are NOT only neurons, but also include cell
types which support brain structure and which nurture neurons. Interestingly, the effects of damage to these cells may not be apparent initially. Damage to supportive
cells may take quite a while to manifest as secondarliy affected neurons become more disabled by the lack of nurture from damaged supportive cells.
Survivors of carbon monoxide poisoning ("Hero Girl Scout Pulls Unconscious Man
From Running Car In Garage. Man is fine.") may slowly reveal the initially unseen damage over months or even years. ("Man Exposed to Fumes, Claims Walking Lost.
Insurer Cries Fake- citing newsreels of him intact.") The typical basal ganglia insult
will manifest over about two years. Children with ataxia, or athetosis often don't get diagnosed for that length of time. It doesn't mean that the symptoms were missed. It
may well mean that the neuron manifestations evolved over time.
Below the ventricles, spreading large blotches or lakes of injury may be found
positioned along key brain centers called ganglia. Ganglia are centers rich in cell bodies, rather than just the long filamentous extensions (called dendrites). These cell
bodies do the brunt of metabolic work which they pass along to the long networking extensions.
Cerebellum related ganglia and base of brain ganglia, when disordered, attack balance
and mid line function - trunk, speech, breathing, coordinated eye symmetry etc. It may also involve specific portions which create a high incidence of severe and hard to
control seizure activity. Quadriplegias often have gross thrusting postures.
Certain ganglia, when injured, cause some joints to posture oddly in reaction to
perceived postures of neighboring joints. Thus, a flexion of the wrist may initiate an extension of the nearest knuckles which then causes the next in line knuckles to flex
while the elbow goes into a responding contortion of its own. That cascade of alternating postures of sequential joints is called dystonia. Some are symmetric and some are asymmetric.
Rigidity is when injury to deep ganglia cause a very high sustained tone which
manifests on both sides of joints - making them feel rigid - or frozen.
Hemiplegia is most commonly from those injuries that follow loss of blood
flow along the middle cerebral artery.
This is key. Diplegia is speckles of injury adjacent the ventricles. Quadriplegia,
damage to oxygen sensitive tissues. Hemiplegia maps along delivery lanes - blood vessels. We are discussing arterial delivery - the paths along which blood flows. The
understanding of involvement reflects the distribution of specific blood vessels.
Regions of brain served by the middle cerebral artery but which also
have alternate blood flow from nearby vessels will be spared or transiently involved then recover.
The zone of brain supplied by the middle cerebral artery minus those portions which also get blood supply from elsewhere is the distribution area of brain injury.
That gives a characteristic pattern of involvement. An arterial blockage may produce
a very small deficit if collateral (extra) arteries are abundant and well connected. Preemies have many extra temporary arteries covering the brain surface and thus
seldom show typical hemiplegia patterns (at least those caused by single artery blockage). In anticipation of the shearing caused by the floating skull plates in the
birth process, these extra vessels from the outer surface are removed late in pregnancy.
But hemiplegias may also result from a right sided or a left sided intracranial
hemorrhage (bleeding). In this case, damage is less road-like (following the artery) and more lake-like (under the pool of bleeding). Occasionally the bleeding, by sheer
volume, can displace the brain and cause secondary injuries well away from the prime bleeding area. These secondary injuries caused by herniation from pressure or
shifting also need to be addressed as additional injuries on top of the hemiplegia. There are only three main arteries. The middle one is the most at risk, hence the
typical pattern of damage.
Hemiplegia may also result from direct trauma to the side of the head. Because of the infinite ways one side of the brain can be wounded, there are many many subtypes
within this designation. Anywhere a trauma may land, a different kind of functional loss can occur. An exactly similar wound in one spot can cause loss of use of one
arm. Moved slightly it could instead damage speech. Moved another way, a blind spot may occur or perhaps a specific memory disorder... maybe behavioral inhibitions get lost.
Like piano keys, same press in different places give differing notes.
The most common postural pattern, that caused by arterial blockage, has the elbow
and wrist flexed and the upper extremity more deficient of hand and arm function than is the leg of walking function. Sensation and self recognition of the part is often
impaired as much or even more than movement per se. Sensory or positional recognition is a serious component of these hemiplegias. We use this designation regardless of how many limbs are involved (mono, di, tri, quad). We might see half
of a hemiplegia. (Who says the entire length of the artery has to be involved?)
The full pattern - if bilateral - is called double hemiplegia rather than quadriplegia because it better describes the characteristic distribution of posture and sensory
deficits seen in the arms and legs than does "quadriplegia" - something of totally differing cause and behavior.
Left brain damage may well also include those brain regions that process what we call language as words - that is - matching words to thought and matching sounds to
selected words and then actually speaking the words.
If the damage is on the right side then speech facility may be normal but it may be lacking in projection of and void of nuance intonation. Receptively, sensory side, words may be understood only by dictionary meaning missing the meaning gleaned
from intonation and context - right brain talents.
Something very vexing in hemiplegia from head trauma - especially and peculiarly
from head trauma - is disease denial. It runs this way:
If I use a cane that means I have weakness. Therefore,
if I refuse the cane - I won't have that weakness.
This ill-logic is maddening to family wearing themselves out trying to go through logic
lists in the hopes of getting correct conclusions and therefore cooperation from the patient.
Sensory disorder, in hemiplegia, often goes unnoticed even though it is what limits
function. In fact, sensory abnormalities what limit use regardless of posture or ability to perform requested movements. Most importantly - from a reconstructive point of
view - no matter how well movement is established and posture improved, function will not follow if sensory deficits do not allow a perception of change. Stated in another way:
Recovery has two main forms.
1: In acute trauma, larger areas of brain are "dazed" than destroyed. As these areas reacquire function we see "recovery". The most central area of damage may well
persist but key functions might nevertheless return.
2: In babies, whose brains are not complete at birth, function might become
reassigned to other parts of the brain well away from the damage. These brain areas are not at all those we would normally associate with the function which returns.
The designations found in anatomy texts indicating normal adult regions of function
do not, therefore, tell us what we really want to know. Will this loss recover? There is recent genetic evidence that a major key to outcome is in the genetics of neurologic healing which is, in essence, the genetic ability to reassign function from injured areas to intact areas of brain - even to the opposite side.
Also in this is the reason that speech is so often intact in children whose brain injuries
would be expected to eliminate speech. Certain genes have been noted to correlate with high levels of injury reversal. Others with poor recovery. The ultimate outcome
may be more related to degree of recovery than to the initial scope of injury.
In fact a very nit picking and fastidious study of new born babies found 7 times the
number of subtle neurologic findings than any of our clinical data (from toddlers) had suggested. The conclusion is that our data of incidence of clinical CP reflects a lower
number of injuries - by far - than actually initially occur. MOST heal. MOST. The span of time was considered to be about seven years. This data is in flux. New
information seems to support these figures as a generality.
So, late brain injury, injury after function has been assigned and hard wired - is
different from early brain injury - before the function is up and running. The plastic infant brain can decide - so to speak - to place the needed function in an intact though
odd location. Injury to the speech center location is different if the injury follows attainment of speech than if before speech is up and running and the center for that
Let's look at the big three subtypes of hemiplegia before considering the sensory
aspects. There is gross mass action type, locked knee type, and free knee type.
Gross mass action type can be likened to the entire body on one side - from shoulder
to toes - being as if of wood, solid.
There is very little actual hip motion if you look closely. Most are fooled and miss that fact. In, say, a left dense hemiplegia, what happens in walking is that when you
think the left hip is flexing you didn't notice that the torso leans back as much as the thigh "flexes" forward. So, in actuality, left hip flexion is occurring through the RIGHT hip.
The intact side develops a really complex mode of movement. The right side is doing
everything. It lifts the left hemi-body off the floor and tilts the entire left side so as to advance the foot forward and then sets the stiff left side down. Once firmly set down
the right side pole vaults, using the rigid left side as the pole.
The left hip joint does nothing. Attacking the left hip flexibility will accomplish
nothing. In fact, the rigidity of the left hip and knee help, as the right side could not depend on what the left side might do if it varied unexpectedly without sharing
(proprioception) how it was varying. In essence it is a peg leg on the left with the entire left side of the body (shoulder to toe) being the peg. Gait is totally right sided
and proprioception is totally right sided.
A dense right hemiplegia is the flip of the above.
Free Hip Type. The free hip type means free hip and only the hip is free. That is, the
right knee behaves stiffly. The stiff knee supports weight. As long as hip mobility has proprioception (position sense) then the motion may be useful. If not, the motion
may translate into instability. The good side needs to know where the opposite foot will be - either by feel or by reliability (as with a peg leg). In the free hip but stiff
knee cases the lure is toward better more energy efficient walking. Despite all the many determinants of gait that have been discussed, in this group the only factor that
works or not is flexion of the involved side knee BEFORE the leg swings.
Unfortunately, gait lingo defines swing phase as when the toe moves foward. More
unfortunately, that was the worst of all possible definitions. An amputee with no knee at all can have a fairly decent walking pattern if the prosthetic knee allows an early
swing of the thigh without acting like a brake.
Forget established gait analysis lingo - it is hopelessly wrongly outdated from the
newer understanding. What swings in walking is the THIGH. Thigh swing is the event to watch (In old lingo that was called preswing). Watch? Why? If it is stiff, won't making it flexible just make it unreliable?
There are two kinds of stiff knee hemiplegia patients. One is a truly neurologically
stiff knee. The other is not stiff at all, but made to appear stiff because of the foot ankle mechanism. Some are both.
The last first. If the foot is stiffly in a down pointing posture, then when weight lands
on the foot the toe hits first and then the heel. The stiff ankle link will thrust the tibia backward and thus lock the knee. The backward thrust tibia with weight on it will
lock like a baby carriage lock and prevent knee flexion. That way swing is blocked by the downward pointing foot. This is called "ground reaction". Ground reaction is not seen only in hemiplegia. It is, however, a particularly prominent source of difficulty in
walking in hemplegia. If you cast or AFO the ankle into dorsiflexion leaving a flexible metatarsal (ball of foot) roll over (flexible or absent toe plate), then the ground
reaction ought to disappear and swing phase knee flexion resume. If that is what happens then attention to the ankle mechanics will tremendously improve walking.
Some of the stiff knee walkers are stiff in the knee because the quadriceps group of
(4) muscles fires just at or before swing phase. In other words, the quadriceps muscle thinks it is one of the hip flexor muscles and is firing along with the hip flexor group. It is the hip flexors which initiate swing phase.
Look closely at the quadriceps and notice that one of the four parts of that muscle
group does not attach to the femur (thigh) bone but rather extends up to the pelvis and can be recruited as a supplemental hip flexor. We use it that way when we need
additional power. However, if that circuitry runs amok, then the quadriceps muscle fires with the hip flexors in walking (ought not) and may recruit by reflex the rest of
the muscle group. The portion of the quadriceps which extends above to the pelvis is called the Rectus Femoris.
If the rectus femoris is simply reacting to stretch when the thigh is extended, then
releasing the upper end from the pelvis will solve the problem. If, however, the rectus femoris is acting solely by mass action with the flexors then detaching it distally and
even reattaching it on the flexion side of the knee will reduce some of that knee locking. Some. Not all, as the recruited portions may still trigger but less so. This
transfer was worked out by Dr. Perry at Ranchos Los Amigos where many adult stroke patients are treated. Some of the childhood hemiplegias have similar reactivity
and may be candidates for that transfer.
There is a danger. When hamstrings are firing very strongly, the quadriceps may have
to counter fire to allow weight bearing. That COMPENSATORY over firing can be
misinterpreted as mass action quadriceps activity. There are many kids who are getting routine transfers of the rectus femoris at the time they are having hamstring
lengthening. In our experience, this reflects that more hamstring is being blamed for overactivity than ought to be. The high velocity components trigger the slower
components (which are far stronger). We feel that if you attack the high velocity portions, then the rest quiets down and the apparent mass action goes away. Why?
Not all mass reaction is from the brain. We were able to mimic this phenomenon in NORMAL volunteers by using elastics that required strong output to overcome (see
elastics). Mass action is a normal process in motion under high tension.
So? The way to distinguish is to play with motion to see if speed induces the prefiring
(premature muscle action) or rather caused by reaction to high resistance regardless of speed. Big difference.
There is a fourth type, named in error, which is really an extended diplegia (PVL)
spared on one side. You can also add other mislabeled types as well given single side sparing. But the reverse is also true. We see some true hemiplegia types (from any
of the three main sorts listed above) added on to other kinds - say diplegia plus stroke.
Sensory Side Issues
Sensory. Just what is sensory? Well the obvious is sense of touch - for sure. But a
whole bunch of other stuff is sensory as well. With your eyes closed, where is your left great toe? Point to it. That obvious knowing of where that and the other parts are
located is called proprioception as was the guidance in pointing. Pull an elastic and hold it stretched. How much tension is this pull? How did you know when to stop?
Dip a spoon in water. Then feel it. How warm is that? Feel the electric clock. Is that thing vibrating? Have somebody spell a word or draw a shape on your palm with
your eyes closed. What was written? Was it a circle or a heart shape? Can you draw a happy face in the air with your eyes shut?
Your are sledding down a hill with eyes shut. Can you tell when the hill levels out?
Can you tell about how fast you went? Can you tell when to put your feet down because you are about ready to hit those trees again?
Somebody called you. How far away? From where?
Oooo. I know that smell.
That light in the distance seems to be getting nearer.
This ground feels soft.
There is a whole bunch more. Getting under a pop up fly ball in order to catch it
requires a complex calculation of trajectory taken from the perceived ascent (downward is way too late, unless you are a really fast runner).
To sit on that chair over there, do you first turn your backside toward the chair and
then walk backwards to the chair and guess when to sit (or keep peeking backwards)? Or, do you first walk directly to the chair then turn and sit? That's called motor
planning. Really good motor planners are called slalom racers or jugglers.
And the point is?
Well, the point is that injury to the brain can affect sensory mechanisms as well as
sensory input. And further, that may be seen as awkwardness. GIGO, garbage in, garbage out. Without adequate input data or processing of that data, even an intact
motor system will appear faulty.
In hemiplegia, due to middle cerebral artery blockage, the sensory region of the brain
is right in the problem area. It could even be more involved than the motor area depending on the luck of having alternate branching blood vessels handy. Very
typically, the sensory loss to the upper extremity is the more serious loss. It can be severe enough to not even register the limb as part of self.
This is important. The hand is primarily a sensory driven part. No matter how good
we make the arm or hand look, if sensory function is poor then function will be poor. The reverse issue is more interesting. No matter how bad the part looks, if sensory
testing is found to be good, then any postural improvement or motor repair will be used to increase function.
For many, transfers and releases in the upper extremity are to enable donning clothing
- specifically to enable getting the arm to and the hand through a sleeve. For others it is to not stand out in a crowd because of a strange posture. A USA presidential
candidate solved that by having a pen in his paralytic hand making the fixed posture appear contextual.
Recent emphasis has been placed on an old idea. We know that motor function can
be reassigned if young enough. How about sensory function? Eye patches have been used for years to promote weak side usage. Periods of good side restriction have
been used to promote weak side usage and avoid the progressive lessening of weak side input. But how about weak side discrimination?
Games that are based on detection and description are valuable. So, reach under the
blanket and bring out the large block. Now find the nail file, not the popsicle stick. Which is the warm spoon? Things like that. Try to bring out discrimination. On that
capability, rides success or failure.
Because of the very fine discrimination and fine control of the hand, even equal
sensory loss in the hand causes worse hand function than leg function. The most needed sensation from the foot relates to timing of walking and confirmation of single
limb support integrity. When sensation is impaired, the timing will get inferred from other means. In tertiary syphilis, sensation in the legs is badly impaired with no loss in
motor function. One can hear a syphilitic coming from way off by the loud slapping of the feet. The slapping isn't a defect in motor control but a means to detect when
the feet have hit the ground - by sound. The eventual result is destroyed joints from injudicious repetative impact. A polio patient with very advanced muscle power loss
often walks because the sensory side is normal and therefore compensatory tricks can be executed with precision.
So in hemiplegia, with a pronated forearm (palm down) and a flexed wrist and thumb
in palm might be much better postured for function with muscles transfers but might not do anything functionally better if sensory mechanisms are not there to modulate
the intended new actions. That does not mean, don't do it. It means don't pin too much hope on postural solutions.
Another oddity. In some inexplicable way, intact sensation figures in growth equalization between the two sides and between muscle components. When sensation
is reduced, the part affected tends to undergrow by a small percentage. This may be the mechanism as to why some muscles undergrow in CP. Maybe. Mmmm. Maybe
not. In any event, in hemiplegia, undergrowth of the affected side is far more parallel to the sensory loss than to the motor function difference between right and left. This
is also true of bone density. There is a lot we don't know.