Ambulation, the ability to move from one place to another, to stand upright and walk to our destination without the risk of falling, is something we take for granted, and later in life or depending on circumstances, it is something we become acutely aware of once the ability is gone. Clearly movement is limited if a leg is injured, fractured, or compromised by medical illness for example resulting in swelling or decreased range of motion as in arthritis. But there are many neurologic diseases that impact ambulation. Moreover, there are many neurologic conditions that may not impact the ability to walk, but present spontaneous movements of limbs or small muscle groups for example in the face. What their significance is, and their long term impact may be, and how amenable to treatment they are, depends on the underlying cause.
Parkinson’s disease is the prototype of movement disorders. It is the one that most will think of when suddenly a tremor appears for the first time. Let me emphasize first that not every tremor means Parkinson’s. And for that matter Parkinson’s is not defined solely by its tremor, nor is it the symptom that most often hinders quality of life. Parkinson’s is a neurodegenerative disorder of the brain. Essentially, once the dopamine producing cells are depleted, the movement difficulties of Parkinson’s disease present themselves. Besides the easily recognized tremor, other symptoms include instability and stooping of posture; a gait described as “festinating” in which slowness to start moving is the main feature; a flattening of facial features with limited expressivity; and importantly for the examiner a quality of the muscle tone in which passive movement of a limb discloses a “ratchety” motion known as cogwheel rigidity. We think of Parkinson’s as a disorder of old age. But the symptoms can be seen earlier in life. And Parkinson’s may occur after exposure to certain toxins, or illness at any age. The risk of fall seen in Parkinson’s is a consequence of the stooped posture: with the shoulders forward and the head leaning one’s center of gravity is suddenly no longer in the abdomen but instead a few inches in front of the abdomen. This forces the individual to “chase” their center of gravity. Walking, which is already slowed, then speeds up to catch the center of gravity and ultimately a fall results. Parkinson’s slows reflexive corrections to prevent the fall from occurring. Replacing the depleted dopamine has been the mainstay of treatment for generations. More recently, surgical interventions may be effective for some patients.
Tic whether presenting in childhood or later in life may be socially injurious to the individual dealing with it, but rarely presents medical concern and treatment can be deferred. Most childhood tics are transient. Some are lifelong. Motor tics can involve small muscle groups and are usually not disruptive or noticeable to others. But when large groups of muscles result in abrupt movement of the head or arm or leg, then is it is very noticeable, potentially resulting in injuries, and treatment is sought. The combination of motor tics and vocal tics is commonly known as Tourette’s.
Chorea is less often seen today owing to the successful treatment of streptococcal infections. In previous generations a slow writhing movement of the limbs, almost like a dance, was seen as a consequence of rheumatic fever. Choreic movements may be seen after vascular events (stroke), or traumatic injuries of the brain. Treatment is limited. sometimes the movements are short-lived and resolve spontaneously.
Cerebellar disorders present following injuries to the brain, vascular events (stroke), or mass lesions (tumor). They can appear as a result of genetic disorders with presentations in early childhood or at some later stage in life. The cerebellum located in the back of the head, allows for fine movements. Someone afflicted with cerebellar disease presents with a slow and scanning type of speech, difficulty walking, and difficulty controlling the muscles of the trunk, with continual “corrective” movements to maintain posture.
Sensory neuropathy or injuries in the peripheral nervous system resulting from metabolic disorder (diabetes), or degenerative genetic disorders of the sensory nerves, also impact movement, and the ability to precisely reach for objects, and to maintain posture and walk safely in the absence of visual input.
We pride ourselves on our ability to get to where we are going. Losing that ability goes to the heart of all those things that in a free society contributes to that feeling of freedom. It represents a loss of independence and autonomy. To be suddenly thrust in the position of having to rely on others to accomplish things we previously did on our own is a psychological blow that diminishes one’s sense of self. Neurologic care, physical therapy, and maintaining overall health are ultimately the cornerstones of recovery.