Bent Spine Syndrome

Bent spine syndrome is also called camptocormia. The word camptocormia originates from Greek words [Camptos (bent)+Kormos (trunk)].  The word camptocormia was used for the first time by Souques and Rosanoff in 1915 in France. Camptocormia [or bent spine syndrome] is defined as an abnormal flexion of the trunk, appearing in standing position, increasing during walking and disappearing in supine position.

Interestingly,  bent spine syndrome was initially considered,  as a psychogenic disorder.

But now it has been established that apart from being a syndrome of psychiatric origin, many cases of bent spine syndrome origin from actual physical causes. Most of these causes originate from muscular diseases out which late onset primary idiopathic axial myopathy has been implicated.

Weakness of the paravertebral muscles can be secondary to diseases affecting the muscular tissue. Camptocormia can be the predominant and sometimes revealing symptom of a more generalized muscular disorder.

Why Does Bent Spine Syndrome Occur?

In standing position, the motion segments of vertebrae are subjected to a forward bending moment which must be counterbalanced by the erector spinal muscles. When erector spinae muscles are weak or insufficient, the equilibrium  between postural dorsal and abdominal muscles is disturbed, leading to a forward bending of the trunk.

On lying down the dynamics of equilibrium changes and the deformity gets corrected.

Bent spine syndrome can be due to ether of following

Primary

It is due to idiopathic muscular weakness in erector spinae [Axial myopathy]. Weakness of the paravertebral muscles leads to degradation of the muscular tissues, independently of their innervation. Primary bent spine syndrome is most common variety encountered.

Secondary

Following causes have been associated with the secondary bent spine syndrome

Dystrophy

• Limb–girdle muscular dystrophy
• Extensive fascio-scapulo-humeral dystrophy

Neuromuscular disorders

• Myotonic muscular dystrophy
• Steinert disease

Inflammatory

• Focal myositis
• Dermatomyositis
• Polymyositis

Endocrine-metabolic

• Hypothyroidism
• Osteomalacia
• Steroid induced
• Amyloidosis

Mitochondrial myopathies

• Carnitine palmityl-transferase deficiency
• Respiratory chain complexes deficiency

Diagnosis of Bent Spine Syndrome

These various causes of secondary BSS must be systematically searched for when faced with an axial myopathy. Clinical examination and laboratory investigations are carried to reach at a diagnosis. From hereon the discussion would be limited to diagnosis of primary bent spine syndrome.

Radio Imaging

Radiography would help to rule out any fixed spinal deformities.

CT scan in primary bent spine syndrome  including dorsal and lumbar sections of the paravertebral muscles is the most useful diagnostic tool. Characteristic findings are

• A normal paraspinal outline
• A normal volume of the muscles, which appear less denser, with loss of substance related to a massive fatty infiltration

In neurogenic atrophy,  the muscle volume decreases, but the density of tissue remains normal.

MRI examination also shows a a similar selective and marked fatty involvement of the paravertebral muscles. Also noted are the rarefaction of muscles fasciculi.

Lab Investigations

The laboratory studies are usually normal. Serum creatine kinase concentration is increased in some cases

No immunologic abnormalities are found. Electromyography findings reveal  a low amplitude pattern

EMG of the lower limbs as well as conduction velocities is usually normal.

Muscle Biopsy

Muscle biopsy reveals a  myopathic pattern showing e disorganization of the normal architecture with replacement of variable intensity of the muscular tissue by fibrosis and fatty infiltration. There is a marked diminution of the number of fibers with variation in fiber size.

Bent spine has also been associated as sign in a few neurological diseases  including  motor neuron disorders and movement and central nervous disorders like parkinsonism, axial dystonia and these should be ruled out.

Treatment

There is no specific drug treatment for primary bent spine syndrome. The treatment includes symptomatic treatment for back pain, treatment of osteoporosis in elderly  to prevent osteoporotic vertebral fractures. Good nutrition, weight control, physiotherapy, massage, exercises and passive motion are an important part of the general management.

Appropriate lightweight orthoses [braces] can help in the ambulation.

In case of secondary bent spine syndrome, the treatable causes such as hypothyroidism should be treated.