Search Results

You are looking at 1 - 10 of 31 items for

  • Author or Editor: Mark G. Hamilton x
  • Refine by Access: all x
Clear All Modify Search
Free access

Mark Hamilton, John Peter Gruen, and Mark G. Luciano

Restricted access


Intraoperative magnetic resonance imaging

Mark M. Souweidane

Restricted access

Mark G. Hamilton and S. Terence Myles

✓ Injury to the spinal column and spinal cord occurs relatively infrequently in the pediatric population. The authors present a unique review of 61 pediatric deaths associated with spinal injury. This group represented 28% of the total pediatric spine-injured population and 45% of the total pediatric spinal cord-injured group studied. The ratio of pediatric to adult spinal injury mortality was 2.5:1. Of the 61 children, 54 (89%) died at the accident scene. Thirty patients underwent a complete autopsy, 19 of whom had an Abbreviated Injury Scale Grade 6 injury (maximum score, untreatable). Spinal cord injury was found to be the cause of death in only eight children and was associated with injury to the high cervical cord and cardiorespiratory arrest. These children typically sustained severe multiple trauma. In this population, there appears to be little room for improved outcome through changes in treatment strategy.

Restricted access

Mark G. Hamilton and S. Terence Mylks

✓ Injury to the spinal column and spinal cord occurs relatively infrequently in the pediatric population. A review of 174 pediatric patients is presented, representing 5.4% of all patients admitted with spinal injury, Spinal cord injury was present in 45% of patients. A distinct injury profile, explained by anatomical and biomechanical features, distinguishes the young patient with an immature spine from older adolescents with a more mature, adult-like spine. The younger patients, while less likely to have spinal injury, had a higher incidence of neurological injury, in addition to a higher frequency of both spinal cord injury without radiological abnormality and upper cervical cord injury. In addition, younger patients with spinal cord injury and no radiological abnormality were more likely to have complete or severe cord injury. Prognosis was determined by the severity of spinal cord injury. Patients with complete cord injuries showed little improvement, while patients with incomplete injuries generally fared much better, with 74% showing significant improvement and 59% experiencing a complete recovery of neurological functions. There were six deaths, but none was attributed solely to spinal injury. The authors conclude that outcome is quite good after pediatric spinal cord injury that does not produce a physiologically complete cord deficit.

Restricted access

Kelly J. Bullivant, Alim P. Mitha, and Mark G. Hamilton

The PS Medical Strata valve is a programmable shunt valve used in the treatment of hydrocephalus that allows for noninvasive changes in the pressure setting using a magnet. The Strata valve is sensitive to magnetic fields, and reprogramming is frequently necessary after MR imaging. A known but rare complication of the Strata valve is that the rotor can become locked, causing shunt malfunction. This complication can only occur in a first generation Strata valve.

Restricted access

Mark G. Hamilton, Bruce I. Tranmer, and Roland N. Auer

✓ Insulin has recently been shown to ameliorate damage in models of global brain ischemia. To determine whether insulin is also neuroprotective in focal ischemia, 20 rats were given 2 to 3 IU/kg insulin and 10 did not receive treatment prior to normothermic transient middle cerebral artery occlusion for 2 hours at a blood pressure of 60 mm Hg. To further elucidate whether infarction volume is influenced by variations in blood glucose levels within the physiological range, blood glucose was raised in 10 of the insulin-treated animals to levels comparable with the untreated controls. At 1-week survival, damage was assessed using quantitative neuropathological examination of 25 coronal planes. It was found that preischemic insulin lowered the mean intraischemic blood glucose level from 8.4 ± 0.2 mM (µ ± standard error of the mean) in the control group to 3.4 ± 0.2 mM and reduced total damage (atrophy plus cortical and striatal necrosis), expressed as the percentage of the normal hemisphere, from a control of 28.5% ± 2.9% to 14.5% ± 1.6% (p < 0.005). Coadministration of glucose and insulin resulted in a mean intraischemic blood glucose level of 10.1 ± 0.5 mM, with 27.0% ± 2.4% total damage (p = 0.96, compared with control). Total ischemic damage showed an independent correlation with blood glucose levels (r = 0.67, p = 0.0018).

The findings indicate that insulin benefits transient focal ischemia and that reducing the blood glucose from 8 to 9 mM to the low-normal range of 3 to 4 mM with insulin dramatically reduces subsequent infarction. The data suggest that the neuroprotective mechanism of insulin action in focal middle cerebral artery occlusion is mediated predominantly via alterations in blood glucose levels. In comparison to global ischemia, focal ischemia appears to show only a minor direct central nervous system effect of insulin. In clinical situations in which transient focal ischemia to the hemisphere can be anticipated, insulin-induced hypoglycemia of a mild degree may be beneficial.

Free access

Albert M. Isaacs, Yarema B. Bezchlibnyk, Heather Yong, Dilip Koshy, Geberth Urbaneja, Walter J. Hader, and Mark G. Hamilton


The efficacy of endoscopic third ventriculostomy (ETV) for the treatment of pediatric hydrocephalus has been extensively reported in the literature. However, ETV-related long-term outcome data are lacking for the adult hydrocephalus population. The objective of the present study was to assess the role of ETV as a primary or secondary treatment for hydrocephalus in adults.


The authors performed a retrospective chart review of all adult patients (age ≥ 18 years) with symptomatic hydrocephalus treated with ETV in Calgary, Canada, over a span of 20 years (1994–2014). Patients were dichotomized into a primary or secondary ETV cohort based on whether ETV was the initial treatment modality for the hydrocephalus or if other CSF diversion procedures had been previously attempted respectively. Primary outcomes were subjective patient-reported clinical improvement within 12 weeks of surgery and the need for any CSF diversion procedures after the initial ETV during the span of the study. Categorical and actuarial data analysis was done to compare the outcomes of the primary versus secondary ETV cohorts.


A total of 163 adult patients with symptomatic hydrocephalus treated with ETV were identified and followed over an average of 98.6 months (range 0.1–230.4 months). All patients presented with signs of intracranial hypertension or other neurological symptoms. The primary ETV group consisted of 112 patients, and the secondary ETV consisted of 51 patients who presented with failed ventriculoperitoneal (VP) shunts. After the initial ETV procedure, clinical improvement was reported more frequently by patients in the primary cohort (87%) relative to those in the secondary ETV cohort (65%, p = 0.001). Additionally, patients in the primary ETV group required fewer reoperations (p < 0.001), with cumulative ETV survival time favoring this primary ETV cohort over the course of the follow-up period (p < 0.001). Fifteen patients required repeat ETV, with all but one experiencing successful relief of symptoms. Patients in the secondary ETV cohort also had a higher incidence of complications, with one occurring in 8 patients (16%) compared with 2 in the primary ETV group (2%; p = 0.010), although most complications were minor.


ETV is an effective long-term treatment for selected adult patients with hydrocephalus. The overall ETV success rate when it was the primary treatment modality for adult hydrocephalus was approximately 87%, and 99% of patients experience symptomatic improvement after 2 ETVs. Patients in whom VP shunt surgery fails prior to an ETV have a 22% relative risk of ETV failure and an almost eightfold complication rate, although mostly minor, when compared with patients who undergo a primary ETV. Most ETV failures occur within the first 7 months of surgery in patients treated with primary ETV, but the time to failure is more prolonged in patients who present with failed previous shunts.