Warm wishes to
all my dear teachers, colleagues and students who motivated me to an attempt to
write this small piece of article for them.
-
Love,
AS
One of the most interesting subjects that we as
physiotherapists interact with is neurosciences. It is an extremely interesting
subject wherein there are multiple challenges and equally interesting results
seen. But somehow, many times the young budding Physios are scared or sceptical
about this subject and majority have an aversion or a poor understanding for
it.
I remember my own experiences as a young undergraduate
student who was totally scared and aversive towards neurology as a clinical
subject. But interaction with 5 Neuro stalwarts changed my perspectives towards
neurology and made me realize that studying neurosciences is as easy as driving
a 2 wheeler or a car.
My elder brother always used to tell me as a young lad
learning to drive a 2 wheeler that the 1st thing you have to know
when you drive any vehicle is to know where the brakes are. Once you start, you
won’t have the time to search for it later. So what happens if there is a
problem with the brake of our vehicle? Obliviously it won’t stop and go out of
control. So do we see such a thing in our body in any diseased condition? Do we
see something like this when the patients cannot control their movements and
tend to go out of control? This is what happens when we have a lesion in the
cerebellum. Thus the cerebellum is the brake of the human body. Involvement of
this system causes our break failure and we tend to see overshooting, inappropriate
stepping, in coordination in walking and other activities. This is what we
classically describe as ataxias.
But by itself the brakes cannot control the vehicle if
we do not control the steering wheel or the handle. Thus it becomes very important
to steer a vehicle properly in order to prevent accidents and reach our
destination. This steering function is by our basal ganglia. Just like steering
control loss would make the vehicle go out of control, similarly involvement of
the basal ganglia can make us go out of control. Such is seen in conditions
like hemiballismus where loss of steering control is seen.
So who drives us then? When we start a car, the engine
starts but the vehicle cannot move. The engine is our wakefulness which is
controlled by the Reticular system. If the reticular system is impaired, we won’t
get ‘started’. Thus the driving force for us is in this system. But is the
reticular system capable of driving us by itself? Even if the engine has
started, it will just continue to be in idling unless we accelerate the
vehicle. The accelerator is very important tool in this. So what happens when
we keep the engine in idling without accelerating? It’s simple, we just won’t
move anywhere. This function of generating stimulus for movement and accelerating
our body is by the motor cortex of the cerebral system. The cortex ensures that
we are accelerated adequately to move in an appropriate manner. So what happens
if our accelerator gets damaged? We will have problems generating that amount
of tone in order to move ahead. This is classically seen in injuries of the
motor cortex like stroke patients. Their engines are at an idling situation but
are unable to accelerate to move their body in a required manner and thus they
generate spasticity.
Also, this engine, in order to move the vehicles, has
to move the axle or the chain/ belt of the vehicle in a proper gear. What can
happen if this axle or belt breaks? Results will be the same. The engine will
keep on idling but will not be able to move the car. Thus axle or belt is the
spinal cord. When it is injured, the brain generates an idling tone but the
limbs cannot move as there is no transmission by the engine to the tyres. This
is what can be seen in paraplegia or quadriplegia.
So then what happens to the car when the engine
starts, we don’t put vehicle in gear but just accelerate? The car would not
move. Instead, it would just create a lot of RPMs and start vigorously
vibrating. The more we accelerate the more sound it would produce and create a
static rigidity. This is classically what would happen when there is lesion of
the extra pyramidal system. The body’s engine starts increasing a lot of tone,
but the person cannot move anywhere. Thus the extra pyramidal system (Substantia
Nigra) is the gear of the human body. We always have to drive our car in the
proper gear or it can damage the engine due to excess RPMs. Even the extra pyramidal
system puts our body in proper gears in order to drive ourselves in proper
systems. So what if my gears don’t work properly? I would produce excess tone
but not able to move properly. Just try driving your car in 1st gear
at speed of 40 or 50 and you will experience a festinating gait. (I didn’t advice
to experiment such driving with the brakes cut). Thus an extra pyramidal system
problem gives us excess tone but no movement. Incase we move, it will be like
speeding in the 1st gear. This is what we see in Parkinson’s
patients, lot of resting movement but no motions as against Cerebellar Ataxias
where there is no movement till vehicle moves, but once it does, there are
movement tremors.
So if we look at things simply, the upper motor
neuron, cerebellar system and extra pyramidal systems are much easy to
understand. So what about the lower motor neuron system? Well, the vehicles
have lots of wiring and cable systems. These connects the battery (heart) to
the lights (visual), horn (auditory), brake cables (nerves), and the AutoCop
security system (skin). Lesions in any of these cables will eventually cause
inability to generate stimulus to that part and thus produce weakness. There
may be a short circuit in the wires where the wire covering may be removed
(neuropraxia) to the point where the entire wire is broken (neurotemesis) and
thus cause problem in handling the car.
Well, there’s still a lot to go on. Recent technology
allows us a lot of luxury while driving. We now have the GPS system which
allows us to detect directions to reach our destination and identifies driving
challenges. This is the role of the frontal cortex which helps in planning and
mapping of tasks and systems and identifies objects. Also the high class
vehicles have a climate (cruise) control system in order to automatically
detect and maintain the temperature and internal atmosphere of the car. This is
what the Hypothalamus does for us.
In spite of all the systems working ok, there would
still be a problem if there is dust in the carburettor or the air filter. Also when
the vehicle will run, the engine will get heated and the vehicle will start
experiencing jerks. Such is the dyspnoea seen in disorders of the respiratory
system. Also what can all these do when the chassis of the car breaks!!! Thus
is the importance of the musculoskeletal system. But heyyy!!!, weren’t we just
discussing neurosciences????
So easy or difficult is up to you all to decide. All I
can say is thanks to my stalwarts of neurosciences and to many others who
have been doing their best to generate interest in neurosciences amongst many
young Physios for years apart. So who says studying neurology is really
difficult. You always learn it when you just drive your car……
Apurv Shimpi
