Anesthesia And Neuromonitoring For Correction Of Thoracolumbar Deformity In An Achondroplastic Dwarf

Achondroplastic Dwarfism (AD) is a type of osteochondrodysplasia identifiable at birth caused by defects in the growth of tubular bone and/or spine. Anesthetic challenges include abnormalities of the airway, cervical spine, pulmonary, cardiac and neurologic systems. We describe the anesthetic management of an achondroplastic dwarf presenting for T6 thru S1 decompression laminectomies, instrumentation and spinal reconstruction with neurologic monitoring. The patient was a 50-year old, 66 kg, 127 cm tall male with spinal stenosis who suffered from severe back pain and thoraco-lumbar myelopathy. Past medical/surgical history included hypertension, thoracolumbar laminectomy, and shoulder arthroscopies. Airway exam showed macroglossia, short mandible with prognathism, large head, short neck & mallampati class III airway. Pulmonary and cardiac evaluations were unremarkable. Neurological exam revealed severe thoracolumbar kyphosis with lumbar lordosis. Standard ASA and bispectral monitors were applied. Spinal cord and lumbosacral roots were monitored via somatosensory evoked potentials (SSEP), electromyogram (EMG) and transcranial evoked potentials (tcMEP). Only upper extremity SSEPs responses were reliable. TcMEPs and SSEPs showed unreliable lower extremity responses. Continuous electromyogram yielded mixed results. Achondroplastic dwarfism poses significant anesthesia challenges. Airway challenges include sleep apnea resulting from brainstem compression and problems with mask ventilation and laryngoscopy, which we did not experience. Intravenous access can be difficult in AD and in our patient necessitated placement of central line. Through the careful titration of anesthetic infusions, we were able to extubate the patient at the conclusion of surgery to perform a neurologic examination. Intra-operative SSEP, EMG and tcMEP monitoring assisted us in avoiding spinal cord ischemia without resorting to a wake up test. Blood loss was minimized with meticulous surgical technique as well as the use of epsilon-aminocaproic acid which has been shown to reduce transfusion requirements in patients undergoing complex spine procedures. We conclude that with adequate anesthetic management, complex spine procedures can be performed on AD patient in a safe manner.