The patient has a large head. Is this normal? Why/why not? What might it signify? How could you evaluate the presence or absence of hydrocephalus? Is this important? Why/why not? How would it alter your anesthetic management if he had normal pressure hydrocephalus? What if this patient had progressive difficulty walking; what would this suggest? How would you evaluate it? How could this be distinguished from his short-limb difficulties?

What are the anesthetic implications of his bony abnormalities? Is this more likely to occur cranially or caudally? Is the spinal defect only a mesodermal defect, or does it involve neuroectoderm as well? The parents want to find out about a spinal; what would you tell them? Is this likely to be easy in this patient (aside from psychological issues)? What level would you choose to perform the block?

Does this patient need soft tissue films of his neck? Why/why not? An airway MRI? C spine films? Why/why not? How will it affect your anesthetic management?

Yes, a large head is normal in achondroplasia patients. While macrocephaly is typical of the syndrome, there is a higher incidence of hydrocephalus due to foramen magnum stenosis. Various imaging modalities will show dilated ventricles. If found, foramen magnum stenosis predisposes to brainstem compression and respiratory arrest. The absence of hydrocephalus or normal pressure hydrocephalus does not rule out the presence of foramen magnum stenosis, and the risk of brainstem compression remains unchanged. This may be due to spinal cord compression from spinal canal stenosis. Imaging of the thoracic and lumbar spine would help with a more specific diagnosis. Difficulty walking owing to short limbs is not associated with neurological symptoms. However, spinal cord compression is associated with lower extremity changes in sensation and motor function. Bladder and rectal sphincter dysfunction may also occur with thoracolumbar stenosis.

Failure of bone growth in this syndrome may result in stenosis of the foramen magnum and spinal canal and vertebral malalignments, most likely in the lumbar spine. Embryologically, the problem is primarily a defect of mesoderm, i.e., the failure of the cartilage to form bone. Lumbar spinal anesthesia has been performed safely in patients with spinal stenosis and vertebral malalignment but is associated with a potentially higher incidence of direct neural injury by the block needle or as a result of epidural bleeding. Therefore, it is advisable to perform spinal anesthesia if it offers distinct advantages over general anesthesia. In this particular patient, there is no obvious benefit of spinal anesthesia over general anesthesia. It is likely to be difficult due to the lordotic deformity and vertebral malalignment. I would choose a site that is not involved with lordosis, kyphosis, stenosis, or vertebral malalignment after reviewing the imaging studies and documenting any preprocedural neurological deficit. L5–S1 may be safe because the deformities are usually located above this level. Nevertheless, the risk of cord compression is possible with the use of a large volume of local anesthetic and epidural venous bleeding.

This patient does not need soft tissue films of the neck. Achondroplasia is a disease of underdevelopment of bone. Midface hypoplasia is expected with this disorder. MRI of the airways can be helpful to determine the extent of airway involvement. As a disorder of bone underdevelopment, achondroplasia can be associated with dysgenesis of the odontoid process, resulting in atlanto-axial instability. The presence of atlanto-axial instability requires protection of the spinal cord from compression by stabilization of the spine in extension during tracheal intubation maneuvers and throughout the perioperative period. Rigid videolaryngoscopy, now readily available, will likely result in a better view of the larynx and glottis without significant manipulation of the head and neck. It is reasonable to anticipate a difficult intubation due to midface hypoplasia, micrognathia, or macrognathia and prepare the patient and the equipment accordingly.

What kind of monitoring (aside from routine) would you choose for this case? Why/why not? Does this patient need an arterial line? Why/why not? A CVP? A precordial Doppler? Why/why not?

Your colleague walks by the room, takes a look in as you are placing monitors, and suggests that you consider a rapid sequence induction because the patient is a preteen, and they all have full stomachs. What do you think? How would you decide which approach to use? Would you use succinylcholine for a rapid sequence induction? Why/why not? Any association with malignant hyperthermia? The patient can extend his neck through an arc of 15–20°. Does this influence your choice of anesthetic induction techniques? How will you do an awake intubation? Would a light wand be just as good as a fiber-optic bronchoscope? Would an anterior commissure scope work just as well for this problem? What are the advantages and disadvantages of each in patients with odontoid hypoplasia and decreased neck extension?

After the first 3 h of the case, six transfemoral Ilizarov struts have been placed; the pulse oximeter reads 94 % on 50 % nitrous and oxygen. What do you make of this? Why/why not?

After the first 4 h of the case, you note that the current nasopharyngeal temperature is 39.7°; the heart rate, which started at 100/bpm, is now 140/bpm. What do you think is going on? What else could it be? How will you evaluate? Is there any way to test? Would you place an arterial line at this point? Give dantrolene prophylactically? What if the end-tidal CO₂ was 43? 57? What if you increased the minute ventilation by 100 %, and the end-tidal CO₂ decreased from 53 to 50? What could this be? Why?