07: On the Level

An individual’s ability to manage their posture and balance is not a skill that is regulated consciously. Three factors control this internal compass: the structure of the inner ear, which consists of liquid whose motion is continuously monitored, proprioception or the body’s “muscle sense” which creates awareness of its trunk and protruding limbs, and finally the individual’s visual field around them. If any one of these factors malfunction, the patient, or in this case Oliver Sacks patient Mr. MacGregor, might experience difficulties in maintaining proper posture (sitting or standing.)

Mr. MacGregor was an aged, yet very healthy man. With the exception of Parkinson’s disease, he was described as “alert, [and] bright as a button.”[1] However, Mr. MacGregor walked with a horrible lean, a full twenty-degree shift from his center of gravity, favoring his left side. Unbeknownst to him, this common side effect of Parkinson’s disease left him unable to walk upright, and although it wasn’t explicitly mentioned by Sacks in the story, there is a high likelihood that Mr. MacGregor exhibited additional postural symptoms; for example, slumping over in his chair.

Proprioception is an integral aspect of deciphering who you are in the world around you. While conscious proprioception facilitates complex motor activity, unconscious proprioception is important for coordinating basic movements. Sensory signaling pathways from the dorsal spinal column terminating in different areas of the brain all work together to keep us “on point” – literally. In addition to brain regions, there are proprioceptors – specialized receptors in the joint, skin, and muscles – that respond and adjust postural movements in each of our bodies, without us having to consciously think about them at all!

Since his condition was simply a byproduct of an overarching neurodegenerative disease, Mr. MacGregror’s treatment options were limited. He was never able to tell when he was leaning over; in fact it was only pointed out to him when he recorded himself and later witnessed with his own eyes that his posture was off. Due to his history with carpentry, he was able to construct a peculiar pair of glasses that included a straight, horizontal level in front of the rim that he could wear and follow. This level gave him visual acuity; although the glasses were cumbersome and caused his eyes some strain, he was physically able to see if he was tilting.

After a few weeks, the task of keeping his eye on the level became less tiring and more automatic. Although it was not a “cure” to his condition, it certainly was an ingenious method of coping with it and was even shared with other patients in his retirement home who were suffering from the same issue.

[1] Sacks, Oliver W. The Man Who Mistook His Wife for a Hat. London: Picador, 1986. Print.