Sunil Patel, Vibhor Krishna, Joyce Nicholas, Charles M. Welzig, and Cristian Vera
Pulsatile arterial compression (AC) of the ventrolateral medulla (VLM) is hypothesized to produce the hypertension in a subset of patients with essential hypertension. In animals, a network of subpial neuronal aggregates in the VLM has been shown to control cardiovascular functions. Although histochemically similar, neurons have been identified in the retro-olivary sulcus (ROS) of the human VLM, but their function is unclear.
The authors recorded cardiovascular responses to electrical stimulation at various locations along the VLM surface, including the ROS, in patients who were undergoing posterior fossa surgery for trigeminal neuralgia. This vasomotor mapping of the medullary surface was performed using a bipolar electrode, with stimulation parameters ranging from 5- to 30-second trains (20–100 Hz), constant current (1.5–5 mA), and 0.1-msec pulse durations. Heart rate (HR) and blood pressure (BP) were recorded continuously from baseline (10 seconds before the stimulus) up to 1 minute poststimulus. In 6 patients, 17 stimulation responses in BP and HR were recorded.
The frequency threshold for any cardiovascular response was 20 Hz; the stimulation intensity threshold ranged from 1.5 to 3 mA. In the first patient, all stimulation responses were significantly different from sham recordings (which consisted of electrodes placed without stimulations). Repeated stimulations in the lower ROS produced similar responses in 3 other patients. Two additional patients had similar responses to single stimulations in the lower ROS. Olive stimulation produced no response (control). Hypotensive and/or bradycardic responses were consistently followed by a reflex hypertensive response. Slight right/left differences were noted. No patient suffered short- or long-term effects from this stimulation.
This stimulation technique for vasomotor mapping of the human VLM was safe and reproducible. Neuronal aggregates near the surface of the human ROS may be important in cardiovascular regulation. This method of vasomotor mapping with measures of responses in sympathetic tone (microneurography) should yield additional data for understanding the neuronal network that controls cardiovascular functions in the human VLM. Further studies in which a concentric bipolar electrode is used to generate this type of vasomotor map should also increase understanding of the pathophysiological mechanisms of neurogenically mediated hypertension, and assist in the design of studies to prove the hypothesis that it is caused by pulsatile AC of the VLM.
Minh H. Nguyen, Krishna Patel, Julie West, Thomas Scharschmidt, Matthew Chetta, Steven Schulz, Ehud Mendel, and Ian L. Valerio
The consequences of failed spinal hardware secondary to wound complications can increase the burden on the patient while also significantly escalating the cost of care. The objective of this study was to demonstrate the effectiveness of a protocol-based multidisciplinary approach in optimizing wound outcome in complex oncological spine care patients.
A retrospective consecutive case series was performed from 2015 to 2019 of all patients who underwent oncological spine surgery. A protocol was established to identify oncological patients at high risk for potential wound complications. Preoperative and postoperative treatment plans were developed by the multidisciplinary tumor board team members. Wound healing risk factors such as diabetes, obesity, prior spine surgery, pre- or postoperative chemotherapy or radiation exposure, perioperative steroid use, and poor nutritional status were recorded. Operative details, including the regions of spinal involvement, presence of instrumentation, and number of vertebral levels operated on, were reviewed. Primary outcomes were the length of hospitalization and major (requiring reoperation) and minor wound complications in the setting of the aforementioned identified risk factors.
A total of 102 oncological cases were recorded during the 5-year study period. Of these patients, 99 had local muscle flap reconstruction with layered closure over their surgical hardware. The prevalence of smoking, diabetes, and previous spine surgery for the cohort was 21.6%, 20.6%, and 27.5%, respectively. Radiation exposure was seen in 72.5% of patients (37.3% preoperative vs 48% postoperative exposure). Chemotherapy was given to 66.7% of the patients (49% preoperatively and 30.4% postoperatively). The rate of perioperative steroid exposure was 60.8%. Prealbumin and albumin levels were 15.00 ± 7.47 mg/dL and 3.23 ± 0.43 mg/dL, respectively. Overall, an albumin level of < 3.5 mg/dL and BMI < 18.5 were seen in 64.7% and 13.7% of the patients, respectively. The mean number of vertebral levels involved was 6.76 ± 2.37 levels. Instrumentation of 7 levels or more was seen in 52.9% of patients. The average spinal wound defect size was 22.06 ± 7.79 cm. The rate of minor wound complications, including superficial skin breakdown (epidermolysis) and nonoperative seromas, was 6.9%, whereas that for major complications requiring reoperation within 90 days of surgery was 2.9%.
A multidisciplinary team approach utilized in complex multilevel oncological spine reconstruction surgery optimizes surgical outcomes, reduces morbidities, and improves care and satisfaction in patients with known risk factors.
Fawaz Al-Mufti, Krishna Amuluru, Abhinav Changa, Megan Lander, Neil Patel, Ethan Wajswol, Sarmad Al-Marsoummi, Basim Alzubaidi, I. Paul Singh, Rolla Nuoman, and Chirag Gandhi
Little is known regarding the natural history of posttraumatic vasospasm. The authors review the pathophysiology of posttraumatic vasospasm (PTV), its associated risk factors, the efficacy of the technologies used to detect PTV, and the management/treatment options available today.
The authors performed a systematic review in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using the following databases: PubMed, Google Scholar, and CENTRAL (the Cochrane Central Register of Controlled Trials). Outcome variables extracted from each study included epidemiology, pathophysiology, time course, predictors of PTV and delayed cerebral ischemia (DCI), optimal means of surveillance and evaluation of PTV, application of multimodality monitoring, modern management and treatment options, and patient outcomes after PTV. Study types were limited to retrospective chart reviews, database reviews, and prospective studies.
A total of 40 articles were included in the systematic review. In many cases of mild or moderate traumatic brain injury (TBI), imaging or ultrasonographic studies are not performed. The lack of widespread assessment makes finding the true overall incidence of PTV a difficult endeavor. The clinical consequences of PTV are important, given the morbidity that can result from it. DCI manifests as new-onset neurological deterioration that occurs beyond the timeframe of initial brain injury. While there are many techniques that attempt to diagnose cerebral vasospasm, digital subtraction angiography is the gold standard. Some predictors of PTV include SAH, intraventricular hemorrhage, low admission Glasgow Coma Scale (GCS) score (< 9), and young age (< 30 years).
Given these results, clinicians should suspect PTV in young patients presenting with intracranial hemorrhage (ICH), especially SAH and/or intraventricular hemorrhage, who present with a GCS score less than 9. Monitoring and regulation of CNS metabolism following TBI/ICH-induced vasospasm may play an important adjunct role to the primary prevention of vasospasm.