Muscle relaxation in persistent vegetative state patients in the hammock

Mag. Barbara Seidel, BSc Dr. Kaar Alfred, Senior Physician, Specialist in Neurology and Psychiatrics

A pilot study of Burgenländische Pflegeheim-Betriebs GmbH, nursing home Oberpullendorf, St. Peter, Persistent Vegetative State Department, a healthcare facility of VAMED and Burgenländische Krankenanstaltengesellschaft, showed that rocking of persistent vegetative state patients in a hammock (vestibular stimulation) reduced muscle tension. According to the study, the reduction in body tension has a positive effect on the patients’ well-being. The research into this application was carried out by a project team in cooperation with the nursing home Oberpullendorf, House St. Peter.

Persistent vegetative state

Persistent vegetative state or unresponsive wakefulness syndrome (abbreviated: PVS or UWS), also known as “coma vigil” describes a state in which a person is awake, but is not aware of himself/herself and his/her environment. In this condition, the eyes are open, but show no signs of consciousness that would be externally recognizable. Vital functions such as breathing or digestion run independently, but targeted movements or communications are not possible. In some cases, PVS patients also have a normal sleep-wake cycle in which they open their eyes during the day without looking at anything and close them again in the evening. PVS is usually the result of severe brain damage caused by traumatic brain injury or lack of oxygen (hypoxia). However, other causes may also lead to PVS, including:

• Stroke
• Meningitis (inflammation of the linings of the brain and spinal cord)
• Brain tumors
• Neurodegenerative diseases (e.g. Parkinson’s disease)

Increased muscle tension

Muscle tension is increased in PVS patients at times, and cramps can occur with increasing tension. Both arms and legs, but also the trunk, are contracted and bent or stretched. The increased body tension results from the destruction of certain areas in the brainstem. These areas are core areas of the brain that form the body’s elementary patterns of movement – the so-called “primitive motor patterns”. Affected areas include:

• Nuclei vestibulares – the “equilibrium cores” of the brain
• Nuclei rubri – the “red core” of the brain
• Formatio reticularis – the “network-like coordination center” of the brain

In PVS patients, these areas of the brain are usually damaged, whereby the primitive motor patterns are activated and massive activation of the flexor and / or extensor muscles occurs. The extent of the extensor or flexor activation intensity depends on the size and location of the brain damage. The increased muscle tension primarily burdens the patients themselves. For example, strong muscle tensions or cramps can be extremely painful and cause increased stress for those affected. The handling of patients in persistent vegetative state is likewise made more difficult for caregivers and therapists, because the movement of the limbs of the patients is markedly hampered by the high muscle tension.

Balance and body tension

Via the equilibrium organ (vestibular organ) in the inner ear, information about the spatial position of the head, as well as the position of the head in relation to the body, are passed on to the central nervous system, where they are processed in the brain stem. Once they have received this, the “equilibrium cores” in the brain ensure that the motor system or the movements of the body adapt to changed conditions in the environment. If this area of​the brain is damaged in PVS patients, the environmental stimuli in the equilibrium organ cannot be properly processed, resulting in restriction of the motor system. By stimulating the equilibrium organ (vestibular stimulation) in the inner ear, however, it is possible to spur the signal processing in the brain and at the same time to reduce the muscular tension of the body.

Stimulation of the sense of balance (vestibular stimulation)

Vestibular stimulation is understood to mean therapeutic measures that comprise excitation or stimulation of the equilibrium organ in the inner ear. When the receptors of the organ are stimulated, the information reaches the “equilibrium kernels” (vestibular nuclei) in the brainstem. The vestibular nuclei are interconnected with the cerebellum, the thalamus, the cortex, and the formatio reticularis. In general, stimulation leads to activation (promotion of alertness) via the ascending reticular system (ARAS).

Nerve fibers run from the equilibrium cores (aka nuclei vestibulares or vestibular cores) via the tractus vestibulospinalis – a descending fiber tract of the vestibular nuclei in the rhombencephalon – into the spinal cord, where they are in direct connection with the motor neurons. Via this connection, vestibular stimulation can lead to a change in muscle tension. Calming vestibular stimuli are uniform movements, such as rocking, swaying, or wheelchair driving, with spinning accelerations acting as activators. Other ways to stimulate the vestibular organ are head movements against the trunk (e.g. trunk rotation), as well as spatial head movements (turning the head in a certain starting position), swinging (while sitting, lying, standing), change of position (e.g. supine seat), placing the body upright (sitting or standing), as well as stimuli on the neck muscles (vibration, tone, pressure).

 Pilot Study: Rocking reduces muscle tension

Burgenländische Pflegeheim-Betriebs GmbH, nursing home Oberpullendorf, St. Peter carried out a pilot study and examined the effect of vestibular stimulation by means of rocking movements in a hammock on muscle relaxation of PVS patients. For the study, a motorized hammock was developed to produce standardized examination conditions (vibrations with a controlled frequency of 10 Hz). The study took a total of 7 weeks, with a two-week break. During the first four weeks, 14 PVS patients were placed 12 times each in a horizontal position in the hammock and rocked for 30 minutes. The following measurements were carried out before and after each 30-minute treatment session with the hammock:

• Measurement of muscle tension using Myoton Pro
• Measurement of vital signs: Blood pressure, oxygen saturation, and pulse

A total of 13 measurements were made. The last measurement was taken two weeks after the four-week therapy period to find out if hammock treatment has a long-term effect on the patient’s organism. In addition, the condition of the patients was observed during transfer to the motorized hammock, during rocking in the hammock, and upon return to the bed.

The result: The comparison of the measurement data between the experimental and control groups has shown that the subjects’ bodies reacted to the rocking movements of the hammock with relaxation. Accordingly, the tipping of the patients’ heads during rocking led to reduction in the basic patterns of movement (”primitive motor patterns”), leading to relaxation in particular of the subjects’ elbow flexors and forefoot extensors. The reduced muscular tension in the patients also led to better physical mobility, which in turn facilitated the nursing and therapeutic handling of the patients. Taking into account the smallness of the sample, the results of the study suggest that rocking in a hammock can regulate the patients’ muscle tension and is a safe therapeutic measure for PVS patients. Due to the positive results of the pilot project, the therapeutic measure using a hammock was integrated into the regular operation of the nursing home Oberpullendorf for muscle relaxation in PVS patients. Since then, the facility has been regarded as a best practice example and flagship facility for the special field of PVS in Austria.

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The co-author, Dr. Alfred Kaar, Senior Physician, Specialist in Neurology and Psychiatry, is the First Senior Physician in Neurology at the public general hospital Oberwart and at the nursing home Oberpullendorf.

The author, Mag. Barbara Seidel, BSc, is the home and nursing service manager of the nursing home Oberpullendorf, a healthcare facility of VAMED and Burgenländische Krankenanstaltengesellschaft.

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