THU0478 MRI Quantitative Analysis of Fatty Infiltration of Paravertebral Muscles in Patients with Primary Camptocormia

Background Camptocormia also referred to as “bent spine syndrome” is characterized by an abnormal trunk posture with marked flexion of the thoraco-lumbar spine. These clinical signs are most prominent on standing and walking and disappears in the recumbent position. There is definitely a broad spectrum of musculoskeletal and neurological etiologies of this disorder which are likely linked to the referral patter. Camptocormia has been associated with muscular dystrophies, inflammatory myopathies, segmental dystonia, amyotrophic lateral sclerosis, mitochondrial myoapthy, dysferlinopathy and Parkinson disease among others. It has been described as a late-onset (over 50 years-old) myopathy with a progressive weakness of the spinal extensor muscles. Increased CK activity and unspecific EMG changes have been reported while computed tomography and Magnetic resonance imaging (MRI) disclosed fat invasion of paravertebral muscles. However, this fat invasion has never been compared to a proper control group so that the effect of age has been ignored. Objectives The main purpose of the present study was to quantify the potential fatty infiltration of paravertebral muscles in patients with primary camptocormia and to compare the corresponding results with those from a age-matched control group. Methods Patients (4, 3 women) and age and sex-matched controls (4). Patients group has been investigated 16.4 ± 3 years after the symptoms onset. We used a spin echo T1 weighted MRI sequence in order to record axial slices of paravertabral muscles (TR/TE = 544/12, matrix size 512*512, FoV 20 cm, slice thickness 5 mm) at 1.5 T (Vision plus, Siemens). Subcutaneous fat (SCF), fatty infiltration (FIF) and muscle (MF) fractions were quantified using a threshold procedure previously described (1). Results were expressed as ratio related to the total content including muscle and fat contents. Mann-Whitney tests (p < 0.05) were used in order to compare both groups. Results The relative intramuscular fat content was actually larger in controls (61±15%) than in patients (38±15%). Correspondingly, the muscle fraction was larger in patients (62 ±19) as compared to controls (39±15%). However, statistical tests failed to demonstrate any difference thereby suggesting that the fatty infiltration of paravertebral muscles previously reported in patients with camptocormia as a myopathic sign should be revisited in the light of ageing. Conclusions This comparative MRI study between patients with ca