Obstetric Anesthetic Management of a Parturient with Larsen Syndrome and Short Stature

Larsen syndrome is a rare congenital anomaly with an incidence of 1 in 100,000 (1) first described by Larsen in 1950 (2). The disorder may be inherited or caused by spontaneous mutation (2–4). The underlying defect is thought to be a collagen malformation resulting in skeletal deformities, including dislocation of multiple large joints (knees, hips, elbows), characteristic hand and feet abnormalities, and vertebral malformations resulting in cervical spine instability (5). Typical facies include hypertelorism, frontal bossing, flattened nasal bridge, and defects of the palate. Cardiac abnormalities may be similar to those observed in Marfan syndrome and can be subdivided into congenital (ventricular and atrial septal defects and patent ductus arteriosis) and acquired (aortic dilation/insufficiency, mitral valve prolapse/insufficiency, and aneurysm of ductus arteriosis) (6). Laryngomalacia, tracheomalacia, bronchomalacia, and subglottic stenosis may complicate airway management (7,8). The literature concerning anesthetic management of Larsen syndrome has focused primarily on the pediatric population. Only three case reports concerning parturients with Larsen syndrome have been published, all in nonanesthesia literature (9–11). We present a case of a parturient with Larsen syndrome and short stature, which is the first description of epidural anesthesia for cesarean delivery in such a patient. Case Report The patient was a 36-yr-old, white female at 34 wk gestation. Her physiognomy was remarkable for extremely short stature and typical Larsen morphology. This was the patient’s fifth pregnancy. Previous pregnancies ended in spontaneous abortion and elective terminations requiring dilation and curettage, all under conscious sedation. Her medical history included bilateral congenital hip dislocations. Physical examination was remarkable for a height of 130 cm, a weight of 36 kilograms, and Mallampati III airway with intact palate. Cervical spine mobility was normal. Cardiovascular examination was significant for a Grade II systolic ejection murmur consistent with increased intravascular volume of pregnancy. Preoperative films revealed a stable atlantoaxial joint and normal cervical range of motion despite significant posterior joint space narrowing. The pregnancy was uncomplicated until 30 wk gestation when the patient began experiencing repeated right hip dislocations and mild dyspnea on exertion, both felt to be an effect of the gravid uterus in this exceptionally small woman. Although ultrasound revealed a grossly normal fetus, the obstetrician believed the small pelvic inlet and limited hip abduction prevented vaginal birth. Surgical delivery was planned. Anesthetic equipment included a pediatric fiberoptic bronchoscope, pediatric laryngoscope and blades, endotracheal tubes sized 4.5–6.0, pediatric gum elastic bougie, and sized 2.0–3.0 laryngeal mask airways in the event that a general anesthetic became necessary. The patient was prehydrated with 1 L of lactated Ringer’s solution and was placed in the flexed sitting position. The multilumen epidural catheter was placed between the second and third lumbar vertebrae with an 18-gauge Tuohy needle by using loss of resistance to saline. The epidural space was reached at 3.5 cm, and the catheter was secured at 7.5 cm at the skin. After a negative test dose of lidocaine with epinephrine, the epidural was dosed in 3-mL increments with 12 mL of 2% lidocaine with epinephrine 1:200,000, 5 μg/mL fentanyl, and 1.2 mL of 8.4% NaHCO3. A sensory level to the third thoracic dermatome was confirmed by pinprick, and surgery proceeded uneventfully. Delivery of a vigorous 2200-g neonate occurred 12 min after the skin incision and 2 min after the uterine incision. The infant’s Apagar scores were 8 and 9, at 1 and 5 min, respectively. The maternal postpartum period was uncomplicated, and she was discharged on postoperative Day 3. Discussion This case was of particular interest because of the patient’s extremely short stature and the many anesthetic challenges presented by the parturient with Larsen syndrome. When managing a patient such as ours, the anesthesiologist must consider the impact of potential craniofacial and vertebral abnormalities, which place these patients at risk for difficult intubation and atlantoaxial subluxation (12). Obtaining flexion and extension films may be helpful in evaluating this risk (13). In addition to the pregnancy-induced changes in respiratory dynamics, the Larsen patient may also present with kyphosis and scoliosis, producing a restrictive respiratory pattern. This may be compounded by the presence of tracheomalacia, bronchomalacia, and subglottic stenosis (13). In these cases, general anesthesia is best avoided, and pulmonary function tests are recommended to aid in managing what can be a complicated respiratory pathophysiology. The choice of epidural anesthesia for this patient was made for several reasons. The clinical efficacy and safety of neuraxial anesthesia is well established in the obstetric population, and the use of an epidural catheter allowed us to titrate the level of neuroaxial blockade and thus minimize the risk of excessive rostral spread. The ability to extend the duration of the block in the event of prolonged surgery was also considered a benefit of a catheter technique. Because of this patient’s abnormal anatomy, the possibility of an unintentional intrathecal puncture was considered, and should that have occurred, we would have reattempted the epidural at the next higher vertebral interspace or considered an intrathecal catheter.