Neurological Osteoporosis in Disabilities

Abstract

Osteoporosis is characterized by low bone mass and destruction of the micro architecture of bone tissue, resulting in increased bone fragility and susceptibility to fractures (NIH 2001). The clinical usefulness of T-score at disabled people on the recognition of people with low BMD remains unclear according to ranking system of the World Health Organization (WHO 1994). Despite the increased number of risk factors in people with disabilities no guidelines are available on BMD measurements; so it would be more appropriate to use the term low bone mass instead of osteoporosis or osteopenia and also take into account the Z-score obtained from the measurement of bone densitometry which is the number of standard deviations above or below that normally expected for someone of similar age, sex, weight and race in question (Dionyssiotis, 2011c, 2011d). In disabled subjects there are differences according to the type of injury (i.e. lesion with a level of injury vs. upper motor neuron pyramidal lesion), the type of lesion; complete (an absence of sensory or motor function below the neurological level, including the lowest sacral segment) vs. incomplete lesion (partial preservation of motor and/or sensory function below the neurological level, including the lowest sacral segment), the progression or not of the disease (i.e. progressive multiple sclerosis vs. complete paraplegia), life expectancy, the residual mobility and functionality, the ability to walk and stand (i.e. incomplete paraplegia vs. quadriplegia vs. high-low paraplegia), drug treatment (i.e. frequent corticosteroid therapy in multiple sclerosis vs. long-term therapy with anticoagulants in paraplegia), the degree of spasticity (i.e. flaccid vs. spastic paralysis) and it is necessary to take into account the issue of fatigue and muscle weakness. Depression in these subjects is usual; complicates the proposed treatments and limits mobility. Complete and incomplete disabled differ also in physical abilities. Moreover, subjects with complete injuries have greater bone loss than those with an incomplete injury (Garland et al., 1994) and as has already been shown in Brown-Sequard subjects (incomplete spinal cord lesion) where BMD of the more paretic knee was lower than that of the stronger knee (Lazo et al., 2001). However, there are also similarities; for example the clinical equivalence of diseases with different physiopathology, location, evolution, etc. A severe form of multiple sclerosis (MS) can result in a wheelchair bound patient having a clinical figure equivalent to spinal cord injury paraplegia. One patient with MS may have better walking gait pattern in comparison with a patient with incomplete paraplegia but may also be unable to walk, bedridden and vice versa (Dionyssiotis, 2011c, 2011d).