Background Primitive progressive lumbar paravertebral muscle weakness commonly known as Primitive Camptocormia and also referred to as “bent spine syndrome” is characterized by an abnormal trunk posture with marked flexion of the thoraco-lumbar spine on standing and walking. It has been described as a late-onset myopathy with a progressive weakness of the spinal extensor muscles associated to a paravertebral muscles fat invasion on the basis of Magnetic resonance imaging (MRI) investigations. In addition, a few case reports have suggested that primitive camptocormia might not be specific of paravertebral muscles but rather a more general myopathy. However, no data of a proper control have been reported so that a age-bias could have been introduced.
Objectives The main purpose of the present study was to quantify fat invasion in thigh muscles of patients with primitive camptocormia using MRI in order to determrine whether camptocormia might be considered as a general myopathy.
Methods Eight patients (7 females) were recruited and investigated 16.4±3 years after the onset of the first symptoms. Four age, and sex-matched control women were included. Mean patients and controls age were 78.8±7.9 and 81.8±5 year-old, weight was 60.1±2.3 and 61±1.4 kg, height was 159±3and 156±2 cms. The MRI sequence protocol included axial slices of the thigh using T1-weighted spin echo (TR/TE =544/12, matrix size 512*512, FoV 20 cm, slice thickness 5 mm) at 1.5 T (Vision plus, Siemens). A semi-automatic home-developed tool was used in order to quantify on each slice the muscle, subcutaneous fat (SCC) and infiltrated fat (IF) compartments (1). Results were expressed as means ratios with respect to the total (fat + muscle) fraction. Mann-Whitney tests (p<0.05) were used in order to compare the different fractions between the two groups.
Results As summarized in table 1, muscle was the larger compartment in both groups with a similar fatty infiltration.
Conclusions On the basis of quantitative MRI measurements, the present results clearly showed that fatty infiltration of thigh muscles, a potential myopathic index, was not larger in patients suffering from a primitive progressive lumbar paravertebral muscle weakness. We also quantified a 20-25% fat infiltration in older subjects. Our results did not confirm those from previous studies suggesting an abnormal muscle fat invasion in primitive camptocormia. However, given that no proper control group was included, the conclusions might have been biased. Muscle fat invasion would then be specific to paravertebral muscles in patients with camptocormia and could not be considered as an index of a general myopathic process.
Mattei, J.P., Y.L. Fur, et al. (2006). Segmentation of fascias, fat and muscle from magnetic resonance images in humans: the DISPIMAG software. Magma 19(5): 275-9).
Disclosure of Interest None Declared
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