Freeman-Sheldon Syndrome (FSS)

At a glance

Freeman-Sheldon Syndrome, or distal arthrogryposis Type 2A, is a rare genetic malformative disorder characterized by microstomia, congenital myopathy and dysplasia characterized by multiple contractures, abnormalities of the head and face, defective development of the hands and feet, and skeletal malformations. The facial muscle contracture produces the typical “whistling face” appearance. Anesthetic issues include difficult intravenous access, difficult airway, and postoperative pulmonary complications. Although an association with malignant hyperthermia has been suggested, this has not been confirmed.

Synonyms

Craniocarpotarsal Disease or Dystrophy; Distal Arthrogryposis Type IIA; Whistling Face Syndrome; Whistling Face-Windmill Vane Hand Syndrome; “Whistler” Syndrome.

Incidence

Unknown. There are less than 80 cases reported in the literature worldwide.

Genetic inheritance

Autosomal dominant inheritance with variable expressivity. No gene has been identified for this condition. No prenatal diagnosis available.

Pathophysiology

Unknown, but it is thought to involve fibrous replacement of muscles fibers.

Diagnosis

Facial features and malformations of limbs are typical. Radiographs of the skull show abnormal appearance of the floor of the anterior cranial fossa. Biopsy of the buccinator muscle reveals fibrous connective tissue. Electromyographic studies show a reduced activity most pronounced in the muscles involved in facial expression.

Clinical aspects

The facies looks immobile with a flat midface, long philtrum, and puckered mouth with whistling shape to lips. The palate is highly arched; mandible and tongue tend to be small; there is an H or V groove on the chin and deeply set eyes with hypertelorism. Patients present with ulnar deviation (90%) and flexion contracture of fingers (88%) accompanied with adduction of the thumb giving the “windmill vane” appearance. Kyphoscoliosis is present in 85% of cases. Talipes equinovarus is common (60%). Intelligence and lifespan are normal.

Precautions before anesthesia

Evaluate the airway for difficult tracheal intubation (microstomia). Use of fiberoptic laryngoscope may be required and should be prepared accordingly. Difficult venous access must be expected. Evaluate physical status: failure to thrive is common as a result of vomiting and swallowing difficulties. Muscle rigidity following halothane anesthesia has been reported, suggesting the presence of an underlying myopathy. Laboratory data should include blood chemistries, blood group, hemoglobin, and coagulation studies.

Anesthetic considerations

Several anesthetic challenges include difficult airway, intravenous cannulation, and the use of regional technique. The presence of facial anomalies is highly suggestive of the potential for difficult airway management. Direct laryngoscopy and tracheal intubation may be difficult, and alternatives (eg, fiberoptic intubation, Bullard laryngoscope, ...