Introduction
Neurological conditions are not common but they occupy a great deal of
time and effort for orthopaedic surgeons. Polio and spina bifida are becoming
increasingly rare in the developed world, as is cerebral palsy. Genetic
counselling has reduced the incidence of the genetic disorders. In the
developing
world many of these conditions remain common but simple public health measures
should reduce these dramatically in the future.
Classification
of neurological disorders
Static,
e.g. polio
Progressive, e.g.
Huntington’s
Sensory,
e.g. leprosy Mixed, e.g. Motor, e.g. polio
disseminated
sclerosis
Flaccid, e.g. peripheral Spastic,
e.g. Abnormal movements,
nerve section
disseminated
e.g. Huntington’s
sclerosis
Static
versus progressive
From an orthopaedic point of view, neurological disorders are classified
into those which are static and those which are progressive. Static disorders
can in fact appear progressive. As an adult gets older and heavier, actions that
were previously possible become impossible despite the fact that there has
Sensory
versus motor
Sensory loss such as that caused by traumatic nerve lesions, leprosy and
multiple sclerosis may create a limb which cannot be protected from injury,
but which is also functionless because the patient does not know where the limb
is (loss of proprioception). Other conditions, particularly polio, are pure
motor loss. Indeed if there is any associated sensory loss a diagnosis other
than polio should be considered. In this case disability and deformity will be a
result of loss of muscle power not loss of sensation.
Flaccid
versus spastic versus abnormal movements
Flaccid paralysis occurs when a peripheral motor nerve is transected or
in the early stages after an upper motor neuron lesion. The limb is flail, and
ligaments are susceptible to damage, simply because there is no muscle power
protecting them. Spastic paralysis is loss of cortical control of muscles
despite the fact that they are’ contracted in spasm and hyperreflexia. The
conversion of an upper motor neuron lesion from flaccid paralysis to spastic
paralysis some days after the original lesion may raise false hopes in the
patient that recovery is imminent. Spastic paralysis will lead to contractures