Is the metacarpal index useful in the diagnosis of Marfan syndrome?

AIM

This study was undertaken to analyse the importance of the Metacarpal Index (MCI) in making the diagnosis of Marfan syndrome.

PATIENTS AND METHODS

The characteristics of 42 patients with Marfan syndrome as defined by strict criteria were analysed. Fifty-one consecutive accident and emergency patients comprised the control group for the MCI measurements.

RESULTS

Using MCI alone four (7.8%) of controls had an abnormal MCI, and seven (16.6%) of Marfan patients were normal. Thirty-two (76%) of Marfan patients had an abnormal MCI and three (13.4%) were equivocal. Using other skeletal parameters (upper segment to lower segment ratio, arm span 3 cm or more greater than height, or palate, pectus or scoliosis deformity) 40 (95%) of the Marfan group had an abnormality. Other parameters: 18 (43%) in the Marfan group gave a history of retinal detachment or ectopia lentis. Echocardiographic measurements showed aortic root dilatation in 29 (69%) and in 21 (50%) mitral valve prolapse was found; 37 (88%) had one or other cardiac abnormality. Using all parameters excluding MCI: All the patients would still have fulfilled the diagnostic criteria for the diagnosis of Marfan syndrome.

CONCLUSION

The role of the MCI, a radiation dependent and time consuming measurement, is probably insignificant in diagnosis of the majority of Marfan patients. Combined with clinical measurements, an echocardiogram is probably the single most useful investigation, aiding both diagnosis and management.