Paul D. Sawin

Cervical spine motion with direct laryngoscopy and orotracheal intubation. An in vivo cinefluoroscopic study of subjects without cervical abnormality.

Background Cervical spine kinetics during airway manipulation are poorly understood. This study was undertaken to quantify the extent and distribution of segmental cervical motion produced by direct laryngoscopy and orotracheal intubation in human subjects without cervical abnormality. Methods Ten patients without clinical or radiographic evidence of cervical spine abnormality underwent laryngoscopy using a #3 Macintosh blade while under general anesthesia and neuromuscular blockade. Cervical motion was recorded with continuous lateral fluoroscopy. The intubation sequence was divided into distinct stages and the corresponding fluoroscopic images were digitized. Segmental motion, occiput through C5, was calculated for each stage using the digitized data. Results During exposure and laryngoscope blade insertion, minimal displacement of the skull base and rostral cervical vertebral bodies was observed. Visualization of the larynx created superior rotation of the occiput and C1 in the sagittal plane, and mild inferior rotation of C3-C5. C2 maintained near-neutral posture. This pattern of displacement resulted in extension at each motion segment, with the most significant motion produced at the occipitoatlantal and atlantoaxial joints (mean = 6.8 degrees and 4.7 degrees, respectively). Intubation created slight additional superior rotation at the occiput and C1, without substantial alteration in the posture of C2-C5. After laryngoscope removal, position trended toward baseline at all levels, although exact neutral posture was not regained. Conclusions This investigation quantifies the behavior of the normal cervical spine during direct laryngoscopy with a Macintosh blade. With this maneuver, the vast majority of cervical motion is produced at the occipitoatlantal and atlantoaxial joints. The subaxial cervical segments (C2-C5) are displaced only minimally. This study establishes a highly reliable and reproducible method for analyzing cervical motion in real time.

Intracranial Pressure and Hemodynamic Effects of Remifentanil Versus Alfentanil in Patients Undergoing Supratentorial Craniotomy

Remifentanil hydrochloride is an ultra-short-acting esterase metabolized mu-opioid receptor agonist. The purpose of this study was to provide preliminary information regarding the effects of this drug on intracranial pressure (ICP) and mean arterial pressure (MAP) in patients scheduled for craniotomy. Twenty-six patients undergoing excision of supratentorial space-occupying lesions were anesthetized with 0.3-0.8 vol% isoflurane in a 2:1 mixture of nitrous oxide:oxygen. Ventilation was adjusted to provide a PaCO2 of <30 mm Hg. After the first burr hole was drilled, patients (n = 5-6 per group) were administered an intravenous infusion of study drug (placebo, remifentanil 0.5 micro gram/kg or 1.0 micro gram/kg, or alfentanil 10 micro gram/kg or 20 micro gram/kg) over 1 min. Epidural ICP and MAP values were recorded at baseline, at completion of infusion, and every minute for the next 10 min. Blood study drug concentrations were measured immediately after completion of infusion. Neither opioid caused a significant increase in ICP. Both drugs were associated with a dose-dependent decrease in MAP. Remifentanil was 31 times more potent than alfentanil for effects on MAP. We conclude that remifentanil produces similar cerebral perfusion pressure effects as does alfentanil. (Anesth Analg 1996;83:348-53)

Cervical spinal cord, root, and bony spine injuries: a closed claims analysis.

Background:The aim of this study was to characterize cervical cord, root, and bony spine claims in the American Society of Anesthesiologists Closed Claims database to formulate hypotheses regarding mechanisms of injury. Methods:All general anesthesia claims (1970–2007) in the Closed Claims database were searched to identify cervical injuries. Three independent teams, each consisting of an anesthesiologist and neurosurgeon, used a standardized review form to extract data from claim summaries and judge probable contributors to injury. Results:Cervical injury claims (n = 48; mean ± SD age 47 ± 15 yr; 73% male) comprised less than 1% of all general anesthesia claims. When compared with other general anesthesia claims (19%), cervical injury claims were more often permanent and disabling (69%; P < 0.001). In addition, cord injuries (n = 37) were more severe than root and/or bony spine injuries (n = 10; P < 0.001), typically resulting in quadriplegia. Although anatomic abnormalities (e.g., cervical stenosis) were often present, cord injuries usually occurred in the absence of traumatic injury (81%) or cervical spine instability (76%). Cord injury occurred with cervical spine (65%) and noncervical spine (35%) procedures. Twenty-four percent of cord injuries were associated with the sitting position. Probable contributors to cord injury included anatomic abnormalities (81%), direct surgical complications (24% [38%, cervical spine procedures]), preprocedural symptomatic cord injury (19%), intraoperative head/neck position (19%), and airway management (11%). Conclusion:Most cervical cord injuries occurred in the absence of traumatic injury, instability, and airway difficulties. Cervical spine procedures and/or sitting procedures appear to predominate. In the absence of instability, cervical spondylosis was the most common factor associated with cord injury.

Aneurysmal bone cyst of the temporal bone presenting as hearing loss in a child

We present an unusual case of a temporal bone and skull base tumor in a ten-year-old child. The patient presented with unilateral hearing loss and headaches. Radiologic, surgical, and histologic findings were consistent with an aneurysmal bone cyst. This is the first report on this rare entity to document its appearance in the temporal bone and skull base using magnetic resonance imaging. Treatment consisted of surgical removal, cranioplasty, and reconstruction of the external auditory canal.

Posterior Interosseous Nerve Palsy after Brachiocephalic Arteriovenous Fistula Construction: Report of Two Cases

Two cases of delayed posterior interosseous nerve palsy after brachiocephalic arteriovenous fistula creation are presented. Both patients suffered from end-stage renal disease, necessitating chronic hemodialysis. After fistula construction, both developed progressive weakness of the muscles innervated by the posterior interosseous nerve. One patient also demonstrated sensory loss in the distribution of the superficial radial nerve. Electrophysiological studies confirmed posterior interosseous mononeuropathies in both cases. Surgical exploration demonstrated posterior interosseous nerve continuity, with severe compression from the hypertrophied venous limb of the arteriovenous fistula. The superficial radial nerve was also compressed in one patient. After neurolysis and fistula revision, both patients recovered neurological function.

Spinal cord compression from metastatic Leydig's cell tumor of the testis: case report.

A case of spinal cord compression from metastatic Leydigs cell tumor of the testis is presented. This 67-year-old man exhibited paraparesis and neurogenic bladder dysfunction secondary to a spinal epidural mass at the T5 level as the initial manifestation of his cancer. Surgical resection was undertaken for tissue diagnosis and spinal cord decompression. The histopathological features of the epidural mass and the excised left testicle were identical, indicative of Leydigs cell carcinoma. The literature is reviewed for previous experience with this exceedingly rare tumor. Unlike most metastatic spinal malignancies, radiation therapy is an ineffectual treatment modality for this tumor. Surgical resection is the only therapeutic option available for amelioration of spinal cord compression.

Posterior Interosseous Nerve Palsy after Brachiocephalic Arteriovenous Fistula Construction

TWO CASES OF delayed posterior interosseous nerve palsy after brachiocephalic arteriovenous fistula creation are presented. Both patients suffered from end-stage renal disease, necessitating chronic hemodialysis. After fistula construction, both developed progressive weakness of the muscles innervated by the posterior interosseous nerve. One patient also demonstrated sensory loss in the distribution of the superficial radial nerve. Electrophysiological studies confirmed posterior interosseous mononeuropathies in both cases. Surgical exploration demonstrated posterior interosseous nerve continuity, with severe compression from the hypertrophied venous limb of the arteriovenous fistula. The superficial radial nerve was also compressed in one patient. After neurolysis and fistula revision, both patients recovered neurological function.