Gait of the Aged (See Also Chap. 28)
An alteration of gait unrelated to overt cerebral disease is an almost universal accompaniment of aging and probably a variant of frontal lobe gait deterioration (Fig. 6-3). Lost with aging are speed, balance, and many of the quick and graceful adaptive movements that characterize the gait of younger individuals. The main objective characteristics are a slightly stooped posture, varying degrees of slowness and stiffness of walking, shortening of the stride, slight widening of the base, and a tendency to turn en bloc. The shortening of stride and widening of the base provide the support that enables the elderly individual to more confidently maintain his balance, but they result in a somewhat guarded gait, like that of a person walking on a slippery surface or in the dark.
Also lacking to a varying degree in the elderly is the ability to make the rapid compensatory postural changes (“rescue responses”) that are necessary to cushion or prevent a fall. A slight misstep, a failure to elevate the foot sufficiently, or tipping of the center of gravity to one side often cannot be corrected—features no doubt that account for the frequency of falls and fear of falling among the elderly. Most persons with this type of gait disturbance are aware of impaired balance and their need for caution to avoid falls (the “cautious gait”; see Nutt et al). As such, this gait lacks specificity, being combined with a general adaptive or defensive pattern of walking. Added to this, knee buckling that is attributable to quadriceps weakness from muscle loss of aging contributes to the problem, as discussed by Felson and colleagues. Furthermore, osteoarthritis, the almost inevitable accompaniment of aging, contributes to the disruption of gait as a result of pain and a reduced range of motion and is a component of many gait disorders.
The nature of the elderly gait disorder is not fully understood. It may simply represent cerebral neuronal loss, attributable to aging itself, which in a severe form is the frontal lobe disorder of gait discussed above. Inadequate proprioception, slowness in making corrective postural responses, diminished vestibular function, and weakness of pelvic and thigh muscles are, as mentioned, probably contributing factors. However, Baloh and colleagues have found that changes in sensory function do not correlate well with deterioration in gait. Fisher remarked on the similarity of the senile gait to that of NPH and suggested that hydrocephalus underlies the gait disorder of some elderly. Cobalamin deficiency caused by gastric atrophy may contribute as well. The multiple contributors to gait deterioration, particularly vestibulopathy, in the aged is reflected in the survey by Fife and Baloh.
We emphasize here the common and vexing problem encountered so often in practice of an elderly person with gait disturbance but minimal dementia and without an obvious etiology. Factor and colleagues identify this as a primary freezing gait disorder of many etiologies and it conforms to “lower-half Parkinson” pattern as discussed earlier. Walking deteriorates over a period of months or years in an elderly individual, sometimes while residing in a nursing home, so that the tempo is unclear. The disturbance has most of the features of NPH or of a frontal gait disorder, but frontal atrophy is not marked, the ventricles are not enlarged, there is no response to drainage of CSF, and cervical spondylosis or neuropathy is not found. Sometimes, a functional imaging study such as positron emission tomography (PET) shows hypometabolism in the frontal lobes. Verghese and coworkers have emphasized the high incidence of subsequent dementia, and this is in accord with experience from our patients. Presumably this reflects a degenerative process, perhaps of the frontotemporal variety. The changes in gait due to aging are nicely summarized in the text by Masdeu and colleagues and the review by Sudarsky.
Gaits of the Developmentally Delayed