Melnick-Needles Syndrome (MNS)

At a glance

It is a genetic disorder characterized by abnormal bone development. Bowing of the bones in the arms and legs is characteristic. Particular facial appearance includes hypertelorism, full cheeks, small facial bones, and severe micrognathia. Other clinical features include a relatively small chest cavity with irregular ribbon-like ribs, short clavicle, short stature, and narrow shoulders. Pectus excavatum is often present. Occasionally, dislocation of the hip occurs. May present hydronephrosis caused by urinary retention caused by small ureters. There is some suggestion that the entity is a form of the fronto-otopalatodigital osteodysplasia syndrome.

Synonyms

Osteodysplasty of Melnick and Needles; Melnick-Needles Osteodysplasty.

History

This medical condition was first described in 1966 by John Welnick (b. 1928), an American radiologist, and Carl F. Needles (b. 1935), an American physician.

Incidence

Fewer than 50 persons described; seems to affect more females than males.

Genetic inheritance

Either an X-linked dominant or autoso­mal sex-limited dominant trait. The Otopalatodigital Syndrome Type II and MNS are likely the result of mutations in the same gene. The difference in expression would be explained by allelic heterogeneity in expression. Most patients are female, but the disease severity is greater in males. The Male-to-female ratio is estimated at 1:7. It is a lethal disease in males.

Pathophysiology

Some cases suggest that this condition is a generalized connective tissue disorder in which an increased content of collagen is found.

Diagnosis

Clinically and radiologically.

Clinical aspects

Considerable heterogeneity, short stature, generalized bone dysplasia. Facial anomalies include a small face with prominent eyes appearing hyperteloric; broad nasal bridge with anteverted nares; micrognathia; sometimes cleft palate; full cheeks; and gingival hypertrophy. It is characterized by the presence of a small chest with ribbon-like ribs, sometimes pectus excavatum; bowing of long bones, mainly tibia and radius (metaphyseal flaring on radiograph), and short upper limbs; vertebral anomalies leading to kyphoscoliosis. In case of severe lung disease, secondary pulmonary hypertension is often associated. Mitral and/or tricuspid valve prolapse, hydronephrosis, omphalocele, hypoplastic kidneys, and urethral obstruction can be associated in some described cases.

Precautions before anesthesia

Check the airway for possible difficult laryngoscopy and tracheal intubation. It is important to obtain an echocardiography to exclude associated cardiac problem (mitral and/or tricuspid valve prolapse) or pulmonary hypertension. Preoperative chest physiotherapy to prevent postoperative complications has been suggested.

Anesthetic considerations

The presence of skeletal dysplasia requires special considerations during positioning of the patient. Special attention to the airway is highly recommended. The presence of micrognathia, hypoplastic coronoid processes of the mandible, left stylohyoid ligament suggesting ossification, and dental development ...