Ultrasound guided nerve block in successful anesthetic management of an achondroplasic dwarf with severe kyphoscoliosis.

Sir,

A 23-year-old man (weight = 34 kg, height = 119 cm) presented with a history of pain in the right foot and fever since 5 days. He gave a history of abnormalities of the limbs and trunk since birth. On examination, his pulse rate was 74/min, blood pressure = 130/80 mmHg, and there was an abscess of the right foot with cellulitis extending up to the level of calf. He had a short stature, kyphoscoliosis, abnormal and short lower limbs. Cardiovascular and respiratory systems were normal except for deformity of the chest. Airway examination revealed a broad nasal bridge, adequate mouth opening, modified Mallampati score — 2, and normal neck movements. There was a kyphoscoliotic deformity involving the entire spine. His hemoglobin concentration was 12.3 g/dl and total leucocyte count = 25730 cells/cm3. Electrocardiogram showed incomplete right bundle branch block. A radiograph confirmed the kyphoscoliosis involving the entire spine from cervical to the lumbosacral region [Figure 1].

Figure 1

Radiograph showing severe kyphoscoliosis involving the entire spine from cervical to lumbosacral region

After initiating routine monitoring, intravenous fentanyl 50 μg and midazolam 1 mg was administered and the patient was put in left lateral position. The right sciatic nerve block was performed at the subgluteal region using a combined ultrasound (out of plane technique) and a peripheral nerve stimulator technique with a 22G 10 cm insulated needle (Stimuplex® A) after eliciting dorsiflexion of the foot. Then, the patient was turned supine and the right femoral nerve block was performed using similar technique (except the in-plane technique for ultrasound) after eliciting contraction of the quadriceps. The local anesthetic mixture contained 12 ml of lignocaine 2% with adrenaline 5 μg/ml + 10 ml of bupivacaine 0.5% + 3 ml of NaHCO3 + 7 ml normal saline (total volume = 32 ml). There were neither any technical difficulties nor any anatomical variations of the nerves noted during the procedure. Drainage of the abscess with debridement up to a few centimeters below the knee was completed successfully in 30 min. However, analgesia lasted only for about 3 h.

Achondroplasia is the most common cause for dwarfism with an approximate incidence of 1.5 in 10,000-1 in 40,000 live newborns with majority (80%) of the cases due to spontaneous mutation.[1234] Achondroplasia is caused by a genetic mutation of the fibroblast growth factor receptor-3, which affects bone growth due to change in endochondral ossification and leads to bone malformation.[5] Due to the defective bone growth with extensive skeletal involvement, both general, and neuraxial anesthesia for these patients may be associated with several difficulties including difficult airway, laryngomalacia, technically challenging neuraxial anesthesia, unpredictable spread of local anesthetics in the epidural space and subarachnoid space and compromised pulmonary function.[45]

Even though, there have been a few cases of successful spinal and epidural anesthesia[3] in such patients undergoing caesarean section, various reports have described technical difficulties during the procedure, increased complications[2] unpredictable spread of local anesthetic,[4] and failure of neuraxial anesthesia. Neurological problems may develop later in life because of compression of the cord due to osteophytes, prolapsed intervertebral discs, and deformed vertebral bodies. Therefore, it has been suggested to avoid neuraxial anesthesia in these patients and anesthesiologists have been reluctant to opt for neuraxial anesthesia.