Objective

To take care of postural disorders is a major issue in Parkinson’s disease (PD). We present a documented observation suggesting the existence of a biased representation of verticality in PD, resulting in a severe retropulsion and recurrent falls. A rehabilitation program aimed to modulate verticality perception dramatically improved the postural perception of the vertical, trunk posture and balance abilities, and reduced retropulsion as well as lastingly fall frequency.

Observations

A 68 year-old patient with Parkinson’s disease fall backward 3 times a day. He presented an important camptocormia. There were no spinal muscular amyotrophy neither spinal canal stenosis on the lumbar tomography. The postural vertical (PV) was tilted backward at –9 (normal PV for this age = –1.2 ± 1.4). Our interpretation was that retropulsion was due to a backward tilt of the internal model of verticality, which led to recurrent falls. Camptocormia was mainly compensatory.

The patient underwent an intensive rehabilitation program of 15 days including: erectus spinae muscles strengthening, realization of postural exercises thanks to mirror, forward modulation of PV. On the basis of theoretical arguments (synthesis of graviceptive vestibular and somatosensory information) and on experimental studies, we also proposed techniques supposed to recalibrate the internal model of verticality: 30 forward tilted posture on a tilt table, bodyweight support walking, vibration of tibialis anterior’s tendons. PV measurements during/just after these techniques confirmed the relevance of this approach. The results were spectacular: 35 mm gain in the measurement of C7 sagittal arrow, 1 point gain in backward disequilibrium scale (BDS) and overall normalization of PV = 0.1. The patient was questioned 2 months later then assessed 6 months later. He continued to daily perform auto-exercises taught, and was very satisfied because of a dramatic reduction of fall frequency, with a feeling to stand better.

Discussion/Conclusion

This observation brings a new insight about the nature of some postural disorders in PD, and suggests the interest of a novel rehabilitation dedicated to the sense of verticality.