yogabook / pathology / multifidus dysfunction

Definition

The deep multifidus is an important muscle for the stability of the spine. Insufficient training stimuli and age-related sarcopenia lead to a loss of performance, but at least as much microtraumas that lead to muscle inhibition. This insufficiency is known as multifidus dysfunction. The scope of the disorder extends far beyond the symptomatic phase. In particular, the strong, deep-seated parts close to the spine, spanning one or two segments, are very important for the stability of the spine. They give the spinal column a certain stiffness and compress neighbouring tissue so that they create segmental stability with the vertebral bodies and the intervertebral discs between them. The superficial parts, which comprise up to five segments, are primarily responsible for the extensory function of the spine. The multifidi are equipped with many muscle spindles, some of which are directly connected to parts of the spinal cord via the spinal cord, which leads to good stability of the spine and contributes significantly to good protection of the spinal cord.
The stability of the spine comes from the passive structures such as vertebral bodies, joints and ligaments, as well as the active structures, i.e. the muscles and the sensorimotor control through reflexes (CNS), which is based on mechanoreceptors (muscles and joints).

Minor trauma can lead to the activation of mechanoreceptors in the capsule of the facet joints or paraspinal muscle spindles, which causes arthrogenic inhibition (Arthrogenic Muscle Inhibition, AMI) of the multifidus. This impairs afferent and efferent information conduction and thus also the segmental control and stability of the spine and the stability of the facet joints. It is also associated with a loss of muscle strength. This functional defect is a form of neuromuscular dysfunction (NMD) and creates microinstability of the spine, which may be an important pathomechanism of chronic low back pain (CLBP). In chronic low back pain, fatty degeneration is often found in the L3-L5 region, which is much more pronounced than in the average population, without the fat percentage being correlated with the general body fat percentage. In a study of 42 test subjects, 70% of whom complained of chronic back pain (at least 12 weeks), the others of acute pain, 85% were found to have fat-degenerated multifidi. This also showed that the flexion of the lumbar spine correlated with the degree of obesity. Furthermore, age correlated with the degree of fatty degeneration, with women being more affected. Chronic cases also showed more pronounced fatty degeneration, regardless of BMI.

AMI and RI can also lead to muscle atrophy. Furthermore, even in early chronic multifidus dysfunction, in addition to fibrosis, there is a transformation of slow type I muscle fibres into fast but less enduring type II muscle fibres, which fatigue much more quickly, as well as a partial fatty degeneration of the muscle mass, which leads to reduced stability of the WS. In the later chronic phase, there is primarily muscle atrophy.

The impairment of the multifidus can cause synergists to overstrain or struggle. Continued training stimuli in the subsequent period can lead to self-limitation of the event as well as its abatement over time, but a permanent loss of function and a structural change in the multifidus is also possible. This poses a risk to the multifidus itself, its synergists and the passive structures, which is further increased by pain avoidance behaviour and often leads to chronicity. Nerve compression also causes disorders of the multifidus. In the chronic course, this leads to specific fatty patterns in the muscles with a corresponding loss of function, as is also found with other distribution patterns in chronic inactivity, i.e. lack of training stimuli, but there with diffuse fatty patterns. The fact that muscle precursor cells increasingly differentiate into fat cells instead of muscle cells due to a lack of exercise stimuli plays a role here. While reflex inhibition caused by trauma primarily disrupts one segment, the disruption caused by nerve compression usually involves several segments.

Back pain

Back pain can impair neuromuscular control; conversely, poorer neuromuscular control can increase pain, creating a vicious circle. If there is also central sensitisation, i.e. an increase in the sensitivity of the CNS, this increases the perception of pain and further impairs neuromuscular control, which means further instability and increased susceptibility to injury for synergists and increased degeneration.

It is therapeutically important to continue adequate training stimuli quickly in order to avoid chronification and also to protect the passive structures. In the case of less pronounced acute disorders, an adapted training stimulus should be sufficient to reverse muscle inhibition. If more extensive fatty patterns and muscle atrophy are already present, however, targeted intensive strengthening training is required, whereby care must be taken to ensure that this does not overload the passive structures. As an alternative to strength training, there have been trials with implant-based muscle stimulation, but no study to date has shown any superiority over training.

The prevalence of multifidus dysfunction is estimated to be in the millions.

ICD

M62.85

Cause

1. injuries
2. Degenerative diseases: intervertebral disc disease, arthritis
3. Lack of training stimuli (chronic underuse) and poor movement and posture habits
4. neuromuscular deficits

Predisposing

1. Poor postural habits
2. Lack of exercise

Symptoms

The picture is not entirely uniform, but the following symptoms are possible

1. lumbar back stiffness
2. Difficulty or pain when lifting even moderately heavy objects
3. Worsening even with simple movements and activities
4. Pain or a feeling of tension when standing or sitting for long periods
5. Changed movement patterns, pain avoidance
6. Strength deficit due to muscle inhibition

Diagnosis

1. MRI
2. Test and signs: Multifidus Lift Test, Prone Instability Test (PIT)

Therapy

1. Strength training, movement training, stretching training
2. Stimulation implant (neurostimulator, not yet based on studies)

Asana practice

According to the function of the multifidus, exercises and asanas that strengthen the extensor function of the lumbar spine are particularly important here, and also in their lateral flexor and rotator function. On the one hand, scaled maximum strength training adapted to the condition of the musculature and the presumed or diagnosed condition of passive structures such as facet joints can be performed. On the other hand, prolonged load in the muscles, as is typical in asanas, may also be favourable. In addition to purely one-dimensional movements, it will also be favourable to address two or three dimensions of movement simultaneously, which works well with some postures.

Furthermore, static errors, axial deviations and muscular imbalances must be investigated and eliminated as far as possible, as they tend to overload the muscles.

Asanas

Postures under 642: Strengthening the muscles of the lumbar spine in its three dimensions of movement.