There are several gait disorders that either may be mistaken for PD or may co-exist with PD. Parkinson dis-ease does not protect you from having another gait disorder. Different gait disorders have different symptoms that help in distinguishing one disorder from another (e.g., whether you take short steps or shuffle while walking, whether you swing your arms while walking, or how easily you fall if pushed backwards, the presence or absence of certain reflexes, the response to levodopa, and the results of an MRI scan of the brain).
Myleopathy refers to a gait disorder that results from pressure on the upper or cervical spinal cord. It is characterized by a scissor-like gait: your feet turning in like the blades of a scissor when you walk along a straight pathway or when you turn. Examination usually reveals weakness of the legs, the deep tendon reflexes are exaggerated, and your big toes curl up after the doctor scratches the soles of your feet with a pin. This last test is called the Babinski response, after the neurologist who first described it.
Normal Pressure Hydrocephalus. Hydrocephalus is a disorder in which there is too much cerebrospinal fluid in the ventricles of your brain. These ventricles enlarge to accommodate the extra fluid and then press on the brain, causing impairment. Normal pressure hydrocephalus (NPH) is a type of hydrocephalus that occurs in older adults, generally 60 years and over. NPH develops gradually, usually over several years. Its exact cause is unknown, although the symptoms are due to the enlarged ventricles pressing on the brain. Symptoms can be grouped into mental symptoms, difficulty walking, and difficulty urinating.
The mental symptoms of NPH can mimic those of Alzheimer’s disease (AD) or PD dementia (Lewy body disease): apathy, anxiety, depression, difficulty paying attention, remembering, and thinking. Testing by an experienced neuropsychologist may help in distinguishing among the mental symptoms of AD, PD, and NPH. The gait disorder of NPH can mimic PD, including the short steps, shuffling, unsteadiness, and freezing of gait (FOG) that occurs. The urinary symptoms can either mimic those of PD or of an enlarged prostate gland: frequency, urgency, and incontinence. An experienced neurologist or a movement disorder specialist may, on the basis of his or her examination, suspect NPH.
Diagnosis of NPH may begin with an MRI that reveals enlarged ventricles. However, the MRI does not indicate whether the ventricles are enlarged due to hydrocephalus, normal age-related brain atrophy, or the atrophy caused by AD or PD dementia. By com-paring the degree of atrophy over the surface of the brain and the size of the ventricles, an experienced neurologist can usually distinguish NPH from brain atrophy.
A neuroradiologist may suggest additional diagnostic tests which vary from center to center. Diagnosis of NPH is also helped by a lumbar puncture (a spinal tap) to measure spinal fluid pressure. An elevated pressure suggests hydrocephalus rather than brain atrophy. However, NPH can exist in the presence of normal pressure (hence the name normal pressure hydrocephalus). A large amount of CSF is removed and analyzed for cells, protein, and sugar. In NPH, the analysis will be negative. The large volume of CSF removed may result in a temporary improvement (24 to 48 hours) of walking difficulty. If such an improvement occurs, it is suggestive of NPH.
Senile Gait/Vascular Parkinson. Shrinkage or atrophy of the brain with a loss of the neurons that regulate walking (senile gait), or a series of strokes that damage the same regions of the brain (vascular PD) can result in a gait disorder that resembles PD. Depending on the degree of atrophy or the location and number of strokes, the walking difficulty of senile gait or vascular PD may include short steps, freezing of gait, and unsteadiness (postural instability). Senile gait may or may not be a forerunner of Alzheimer disease. An experienced neurologist or a movement disorder specialist can usually distinguish senile gait or vascular PD from PD.
Examination will include leg muscle tone and how their resistance to being stretched differs. Parkinson disease is characterized by rigidity, while senile gait and vascular PD by spasticity and gengenhalten (involuntary resistance to passive movement of the extremities). Deep ten-don reflexes may be increased in senile gait and vascular PD, but are normal in PD. Babinski signs and a reflex called the “tonic foot” or “grasp” (the sole of the foot gripping the ground) are present in both senile gait and vascular PD, but absent in PD. While walking and leg tone are affected in senile gait and vascular PD, the arms remain unaffected, unlike in PD. Thus in senile gait or vascular PD the arms swing while walking, but one or both don’t in PD.