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Nader S. Dahdaleh

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Nader S. Dahdaleh and Arnold H. Menezes

The combination of unilateral trigeminal and vagal nerve dysfunction is a rare presentation in patients with Chiari malformation Type I (CM-I). The authors present a case of incomplete lateral medullary syndrome in a patient with CM-I. The patient's symptoms of decreased unilateral facial sensitivity to pain and temperature and her vocal cord dysfunction reversed after posterior fossa decompression and intradural exploration. Although rare, clinicians should be aware of this presentation as part of a protean spectrum of symptoms in patients with CM-I.

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Brian J. Dlouhy, Nader S. Dahdaleh, Arnold H. Menezes, and MD

The craniovertebral junction (CVJ), or the craniocervical junction (CCJ) as it is otherwise known, houses the crossroads of the CNS and is composed of the occipital bone that surrounds the foramen magnum, the atlas vertebrae, the axis vertebrae, and their associated ligaments and musculature. The musculoskeletal organization of the CVJ is unique and complex, resulting in a wide range of congenital, developmental, and acquired pathology. The refinements of the transoral approach to the CVJ by the senior author (A.H.M.) in the late 1970s revolutionized the treatment of CVJ pathology. At the same time, a physiological approach to CVJ management was adopted at the University of Iowa Hospitals and Clinics in 1977 based on the stability and motion dynamics of the CVJ and the site of encroachment, incorporating the transoral approach for irreducible ventral CVJ pathology. Since then, approaches and techniques to treat ventral CVJ lesions have evolved. In the last 40 years at University of Iowa Hospitals and Clinics, multiple approaches to the CVJ have evolved and a better understanding of CVJ pathology has been established. In addition, new reduction strategies that have diminished the need to perform ventral decompressive approaches have been developed and implemented.

In this era of surgical subspecialization, to properly treat complex CVJ pathology, the CVJ specialist must be trained in skull base transoral and endoscopic endonasal approaches, pediatric and adult CVJ spine surgery, and must understand and be able to treat the complex CSF dynamics present in CVJ pathology to provide the appropriate, optimal, and tailored treatment strategy for each individual patient, both child and adult. This is a comprehensive review of the history and evolution of the transoral approaches, extended transoral approaches, endoscopie assisted transoral approaches, endoscopie endonasal approaches, and CVJ reduction strategies. Incorporating these advancements, the authors update the initial algorithm for the treatment of CVJ abnormalities first published in 1980 by the senior author.

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Brian J. Dlouhy, Nader S. Dahdaleh, and Jeremy D. W. Greenlee

Improvement in fiber optics and imaging paved the way for tremendous advancements in neuroendoscopy. These advancements have led to increasingly widespread use of the endoscope in neurosurgical procedures, which in turn incited a technological revolution leading to new approaches, instruments, techniques, and a diverse armamentarium for the treatment of a variety of neurosurgical disorders. Soft-tissue removal is often a rate-limiting aspect to endoscopic procedures, especially when the soft tissue is dense or fibrous. The authors review a series of cases involving patients treated between August 2009 and October 2010 with a new device (the NICO Myriad), a non–heat-generating, oscillating, cutting, and tissue removal instrument that can be used through the working channel of the endoscope as well as in open neurosurgical procedures. They used this device in 14 purely endoscopic intracranial procedures and 1 endoscope-assisted keyhole craniotomy. They report that the device was easy to use and found that tissue resection was more efficient than with other available endoscopic instruments, especially in the resection of fibrotic tissue. There were no observed device-related complications. The authors discuss the technical aspects of using this device in endoscopic resection of pituitary tumors, craniopharyngiomas, and colloid cysts. They also demonstrate its use in hydrocephalus and intraventricular clot removal and discuss its potential use in other neurosurgical disorders.

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Nader S. Dahdaleh, Brian J. Dlouhy, and Arnold H. Menezes


The treatment of basilar invagination in the pediatric age group is dependent on the possibility of preoperative reduction. Reducible lesions obviate a ventral decompression and require a dorsal-only approach for stabilization with or without a suboccipital decompression.


The authors describe a technique of intraoperative reduction of basilar invagination with the use of general anesthesia and neuromuscular blockade in the presence of crown halo traction. Using the O-arm device, a 3D CT scan is generated in the sagittal plane to demonstrate the reduction intraoperatively. This technique was successful in 6 pediatric patients with basilar invagination.


The average age of the patients was 10.8 years, and they were followed for a mean period of 8.5 months. The patients had mild basilar invagination or partial reduction in extension on preoperative MR imaging. Intraoperative reduction was demonstrated in all patients by using the reported technique with intraoperative CT. All patients underwent occipitocervical fusion, and all but one underwent a suboccipital decompression. There were no complications related to the operation, and all but one reported improvement of symptoms on the last postoperative visit.


Intraoperative reduction performed using neuromuscular blockade and intraoperative traction is an effective method for further reduction of basilar invagination in the pediatric age group. This is the first reported application of intraoperative CT imaging performed using the O-arm device in craniocervical surgery in which successful reduction is demonstrated in detail.

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Michael Brendan Cloney, Jack Goergen, Benjamin S. Hopkins, Ekamjeet Singh Dhillon, and Nader S. Dahdaleh


Venous thromboembolic events (VTEs) are a common cause of morbidity and mortality after spine surgery. Patients admitted to the intensive care unit (ICU) following spine surgery exhibit high-risk clinical characteristics.


The authors retrospectively analyzed 1269 ICU patients who had undergone spine surgery between January 1, 2009, and May 31, 2015. Relevant demographic, procedural, and outcome variables were collected.


Patients admitted to the ICU postoperatively had a postoperative VTE rate of 10.2%, compared to 2.5% among all spine surgery patients during the study period. ICU patients had a higher comorbid disease burden (odds ratio [OR] 1.45, p < 0.001), and were more likely to have a history of a bleeding disorder (2.60% vs 0.46%, OR 2.85, p = 0.028), receive a transfusion (OR 4.81, p < 0.001), have a fracture repaired (OR 4.30, p < 0.001), have an estimated blood loss > 500 ml (OR 1.95, p = 0.009), have an osteotomy (OR 20.47, p = 0.006), or have a corpectomy (OR 3.48, p = 0.007) than patients not admitted to the ICU. There was a significant difference in time to VTE between patients undergoing osteotomy and patients undergoing scoliosis corrections without osteotomy (p = 0.0431), patients with fractures (p = 0.0113), and patients undergoing fusions for indications other than scoliosis or fracture (p = 0.0056). Patients who developed a deep vein thrombosis (DVT) during their ICU stay were more likely to have received a prophylactic inferior vena cava filter placement (OR 8.98, p < 0.001), have undergone an interbody fusion procedure (OR 2.38, p = 0.037), have a history of DVT (OR 3.25, p < 0.001), and have shorter surgery times (OR 0.30, p = 0.002). Patients who developed a pulmonary embolism (PE) during the ICU stay were more likely to have a history of PE (OR 12.68 p = 0.015), history of DVT (OR 5.11, p = 0.042), fracture diagnosis (OR 7.02, p = 0.040), and diagnosis of scoliosis (OR 7.78, p = 0.024). Patients with higher BMIs (OR 0.85, p = 0.036) and those who received anticoagulation treatment (OR 0.16, p = 0.031) were less likely to develop a PE during their ICU stay.


Patients admitted to the ICU following spine surgery have a higher rate of VTE than non-ICU patients. Time to VTE varied by pathology. Factors independently associated with VTE in the ICU are distinct from factors otherwise associated with VTE. Some factors are independently associated with VTE throughout the 30-day postoperative period, while others are associated with VTE specifically during the initial ICU stay or after leaving the ICU.