Characterizing the Response to Cerebrospinal Fluid Drainage in Patients with an External Ventricular Drain: The Pressure Equalization Ratio.

BACKGROUND: An external ventricular drain (EVD) is the gold standard for measurement of intracranial pressure (ICP) and allows for drainage of cerebrospinal fluid (CSF). Different causes of elevated ICP, such as CSF outflow obstruction or cerebral swelling, respond differently to CSF drainage. This is a widely recognized but seldom quantified distinction. We sought to define an index to characterize the response to CSF drainage in neurocritical care patients. METHODS: We studied consecutive patients admitted to the neurointensive care unit who had an EVD. The EVD was closed for 30 min prior to assessment. We documented pre-drainage ICP, opened EVD to drainage allowing CSF to drain until it ceased, and recorded post-drainage ICP at EVD closure. We calculated the pressure equalization (PE) ratio as the difference between pre-drainage ICP and post-drainage ICP divided by the difference between pre-drainage ICP and EVD height. RESULTS: We studied 60 patients (36 traumatic brain injury [TBI], 24 non-TBI). As expected, TBI patients had more signs of cerebral swelling on CT and smaller ventricles. Although TBI patients had significantly higher pre-drainage ICP (26 ± 10 mm Hg) than non-TBI patients (19 ± 5 mm Hg, p < 0.001) they drained less CSF (7 cc vs. 4 cc, p < 0.01). PE ratio was substantially higher in non-TBI than in TBI patients (0.86 ± 0.36 vs. 0.43 ± 0.31, p < 0.0001), indicating that non-TBI patients were better able to equalize pressure with EVD height than TBI patients. CONCLUSIONS: PE ratio reflects the ability to equalize pressure with the preset height of the EVD and differs substantially between TBI and non-TBI patients. A high PE ratio likely indicates CSF outflow obstruction effectively treated by CSF diversion, while a lower PE ratio occurs when cerebral swelling predominates. Further studies could assess whether the PE ratio would be useful as a surrogate marker for cerebral edema or the state of intracranial compliance.

A swine model of intracellular cerebral edema - Cerebral physiology and intracranial compliance.

Cerebral edema leading to elevated intracranial pressure (ICP) is a fundamental concern after severe traumatic brain injury (TBI), stroke, and severe acute hyponatremia. We describe a swine model of water intoxication and its cerebral histological and physiological sequela. We studied female swine weighing 35-45 kg. Four serum sodium intervals were designated: baseline, mild, moderate, and severe hyponatremia attained by infusing hypotonic saline. Intracranial fluid injections were performed to assess intracranial compliance. At baseline and following water intoxication wedge biopsy was obtained for pathological examination and electron microscopy. We studied 8 swine and found an increase in ICP that was strongly related to the decrease in serum sodium level. Mean ICP rose from a baseline of 6 ±â€¯2 to 28 ±â€¯6 mm Hg during severe hyponatremia, while cerebral perfusion pressure (CPP) decreased from 72 ±â€¯10 to 46 ±â€¯11 mm Hg. Brain tissue oxygen tension (PbtO2) decreased from 18.4 ±â€¯8.9 to 5.3 ±â€¯3.0 mm Hg. Electron microscopy demonstrated intracellular edema and astrocytic foot process swelling following water intoxication. With severe hyponatremia, 2 cc intracranial fluid injection resulted in progressively greater ICP dose, indicating a worsening intracranial compliance. Our model leads to graded and sustained elevation of ICP, lower CPP, and decreased PbtO2, all of which cross clinically relevant thresholds. Intracranial compliance worsens with increased cerebral swelling. This model may serve as a platform to study which therapeutic interventions best improve the cerebral physiological profile in the face of severe brain edema.

Primary pleomorphic liposarcoma of the thoracic epidural space: case report.

BACKGROUND CONTEXT: Pleomorphic liposarcoma (PLS) is a rare malignant soft tissue tumor comprising 5%-15% of liposarcomas and characterized by high malignant potential. To our knowledge only three cases of this entity have been reported in the spine. PURPOSE: We describe the only reported case of a purely epidural PLS with no macroscopic bone involvement at diagnosis. STUDY DESIGN/SETTING: A case presenting clinical evidence that PLS may arise from the epidural fat is reported. METHODS: The clinical presentation, management, and outcome in a case of primary PLS of the thoracic spine, and a review of the literature, are presented. RESULTS: A 70-year-male presented with sudden onset lower extremity weakness, constipation, and back pain. Magnetic resonance imaging revealed an epidural lesion at T5 with noted mass effect compressing the spinal cord and extension to the T5-T6 foramen. Urgent decompressive laminectomy with gross total resection was performed. Histopathology revealed high-grade PLS. Adjunct radiotherapy was prescribed. The tumor recurred 3 months later. In spite of repeat surgery, additional radiation, and chemotherapy, the patient developed widespread metastases and succumbed to his disease 1 year after treatment began. CONCLUSIONS: Spinal PLS is a rare entity, but nonetheless may arise from epidural fat and should be considered in the differential diagnosis of primary spinal cord lesions.

Constant Current versus Constant Voltage Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease.

Background: Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established therapy for advanced Parkinson's disease (PD). Motor efficacy and safety have been established for constant voltage (CV) devices and more recently for constant current (CC) devices. CC devices adjust output voltage to provide CC stimulation irrespective of impedance fluctuation, while the current applied by CV stimulation depends on the impedance that may change over time. No study has directly compared the clinical effects of these two stimulation modalities. Objective: To compare the safety and clinical impact of CC STN DBS to CV STN DBS in patients with advanced PD 2 years after surgery. Methods: Patients were eligible for inclusion if they had undergone STN DBS surgery for idiopathic PD, had been implanted with a Medtronic Activa PC and if their stimulation program and medication had been stable for at least 1 year. This single-center trial was designed as a double-blind, randomized, prospective study with crossover after 2 weeks. Motor equivalence of the 2 modalities was confirmed utilizing part III of the Unified Parkinson's Disease Rating Scale (UPDRS). PD diaries and multiple subjective and objective evaluations of quality of life, depression, cognition and emotional processing were evaluated on both CV and on CC stimulation. Analysis using the paired t test with Bonferroni correction for multiple comparisons was performed to identify any significant difference between the stimulation modalities. Results: 8 patients were recruited (6 men, 2 women); 1 patient did not complete the study. The average age at surgery was 56.7 years (range 47-63). Disease duration at the time of surgery was 7.5 years (range 3-12). Patients were recruited 23.8 months (range 22.5-24) after surgery. At the postoperative study baseline, this patient group showed an average motor improvement of 69% (range 51-97) as measured by the change in UPDRS part III with stimulation alone. Levodopa equivalent medication was reduced on average by 67% (range 15-88). Patients were poorly compliant with PD diaries, and these did not yield useful information. The minor deterioration in quality-of-life scores (Parkinson's Disease Questionnaire-39, Quality of Life Enjoyment and Satisfaction Questionnaire) with CC stimulation were not statistically significant. Two measures of depression (Hamilton Rating Scale D17, Quick Inventory of Depressive Symptomatology - Self-Report) showed a nonsignificant lower score (less depression) with CC stimulation, but a third (Beck Depression Inventory) showed equivalence. Cognitive testing (Mini Mental State Examination) and emotional processing (Montreal Affective Voices) were equivalent for CC and CV. Conclusion: CC STN DBS is safe. For equivalent motor efficacy, no significant difference could be identified between CC and CV stimulation for nonmotor evaluations in PD patients 2 years after surgery. © 2015 S. Karger AG, Basel.

Higher neuronal discharge rate in the motor area of the subthalamic nucleus of Parkinsonian patients.

In Parkinson's disease, pathological synchronous oscillations divide the subthalamic nucleus (STN) of patients into a dorsolateral oscillatory region and ventromedial nonoscillatory region. This bipartite division reflects the motor vs. the nonmotor (associative/limbic) subthalamic areas, respectively. However, significant topographic differences in the neuronal discharge rate between these two STN subregions in Parkinsonian patients is still controversial. In this study, 119 STN microelectrode trajectories (STN length > 2 mm, mean = 5.32 mm) with discernible oscillatory and nonoscillatory regions were carried on 60 patients undergoing deep brain stimulation surgery for Parkinson's disease. 2,137 and 2,152 multiunit stable signals were recorded (recording duration > 10 s, mean = 21.25 s) within the oscillatory and nonoscillatory STN regions, respectively. Spike detection and sorting were applied offline on every multiunit stable signal using an automatic method with systematic quantification of the isolation quality (range = 0-1) of the identified units. In all, 3,094 and 3,130 units were identified in the oscillatory and nonoscillatory regions, respectively. On average, the discharge rate of better-isolated neurons (isolation score > 0.70) was higher in the oscillatory region than the nonoscillatory region (44.55 ± 0.87 vs. 39.97 ± 0.77 spikes/s, N = 665 and 761, respectively). The discharge rate of the STN neurons was positively correlated to the strength of their own and their surrounding 13- to 30-Hz beta oscillatory activity. Therefore, in the Parkinsonian STN, beta oscillations and higher neuronal discharge rate are correlated and coexist in the motor area of the STN compared with its associative/limbic area.

Excellent rates of recanalization and good functional outcome after stent-based thrombectomy for acute middle cerebral artery occlusion. Is it time for a paradigm shift?

The natural history of untreated acute middle cerebral artery (MCA) occlusion is poor, with high rates of mortality (5-33%) and severe long-term disability (40-80% of survivors), despite therapy with intravenous tissue plasminogen activator. We analyzed outcomes in 31 consecutive patients with major ischemic stroke due to acute proximal MCA occlusion who were treated at the Hadassah-Hebrew University Medical Center from February 2010 to October 2012 by endovascular means, using the Solitaire stent (Covidien, Irvine, CA, USA) as a thrombectomy device. Patients had a mean age of 63.3±16.2 years (range, 26-92). The admission National Institutes of Health Stroke Scale score was 19.5±4.3 (median 20). Mean time from symptom onset to femoral artery puncture was 3.8±1.1 hours (median 4 hours). Mean time to recanalization was 46.9±11.1 minutes. Successful recanalization by means of stent-based thrombectomy alone was achieved in 90% of cases and reached 100% after combining definitive stent implantation in three patients. There was no arterial rupture or subarachnoid hemorrhage. Hemorrhagic transformation developed in seven patients (23%), but was symptomatic in only one. Post-procedure CT scan or MRI demonstrated >90% sparing of cortex at risk in all patients. Functional outcome at 90 day follow-up was modified Rankin Score 0-2 in 77% of all patients and 88% of patients younger than 80 years. Three patients (10%) died during hospitalization due to mesenteric event, sepsis, or pulmonary embolism. Our experience suggests that stent-based thrombectomy in selected patients for acute MCA occlusions is safe, very effective in terms of arterial recanalization, and associated with improved neurological outcome. If validated by other groups, endovascular treatment may be proposed as the therapy of choice for MCA occlusion.

Clinical relevance of negative initial angiogram in spontaneous subarachnoid hemorrhage.

BACKGROUND: We aimed to compare the presentation, management, and clinical course in patients with perimesencephalic and nonperimesencephalic (aneurysmal) bleeding patterns on noncontrast CT, but negative initial 4-vessel digital subtraction angiography (DSA). METHODS: We retrospectively reviewed clinical and imaging data for 280 patients presenting with spontaneous SAH admitted between 2005 and 2011. We identified 56 patients (20%) with SAH diagnosed on high resolution head CT performed within 48 hours of admission, and negative initial DSA, and divided them into perimesencephalic and non-perimesencephalic groups based on hemorrhage patterns. Patients with traumatic subarachnoid bleeding and those with initial positive DSA were excluded from this analysis. RESULTS: Perimesencephalic SAH was seen in 25 patients (45%); non-perimesencephalic bleeding patterns were seen in 31 (55%). All patients with perimesencephalic SAH presented with Hunt and Hess (HH) I, versus 45% HH I and 55% HH II-IV in those with non-perimecenphalic SAH. All patients with perimesencephalic SAH achieved modified Rankin score (mRS) 0 at discharge and 6-month follow-up, compared with 45% mRS 0 at discharge and 68% at 6-month follow-up in non-perimesencephalic SAH. Patients with perimesencephalic SAH presented a uniformly uncomplicated clinical course. Among non-perimesencephalic SAH patients there were 19 neurological/neurosurgical and 10 medical complications, two small aneurysms diagnosed at follow-up DSA, and one death. CONCLUSIONS: In this series, perimesencephalic SAH was associated with good clinical grades, consistently negative initial and follow-up angiograms, and an excellent prognosis. In contrast, non-perimesencephalic SAH was associated with a worse clinical presentation, higher complication rates, higher rates of true aneurysm detection on follow-up angiogram, and a poorer outcome.

Stent-based thrombectomy versus intravenous tissue plasminogen activator in patients with acute middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: Our goal was to compare outcomes of patients with proximal middle cerebral artery occlusions treated with intravenous tissue plasminogen activator (tPA) with those of patients treated with stent-based thrombectomy (SBT). METHODS: Patients with proximal middle cerebral artery occlusions included in our prospective stroke registry were identified. Patients presenting with moderate to severe stroke defined as National Institutes of Health Stroke Scale score≥10 were included. Patients treated with tPA were compared with those treated with SBT. Disability was measured with the modified Rankin Scale and shifts toward favorable outcomes (modified Rankin Scale≤2) were analyzed. Logistic regression was used to determine outcome modifiers. RESULTS: We included 22 patients treated with SBT and 66 treated with tPA. Patients treated with SBT had higher admission National Institutes of Health Stroke Scale scores (median 21 vs 14.5; P<0.001) and prolonged symptom onset-to-treatment times (median 240 vs 95 minutes; P<0.001). At discharge, the magnitude of change in National Institutes of Health Stroke Scale was larger in the thrombectomy group (median 12 vs 6 points; P<0.001). At 90 days poststroke there was a shift toward favorable outcome in the thrombectomy group (60% vs 37.5%; P=0.001). Treatment allocation did not impact outcome in the regression analysis. CONCLUSIONS: Treatment of patients with proximal middle cerebral artery occlusions with SBT resulted in a shift toward more favorable outcomes compared with tPA. Randomized controlled studies are needed to explore whether treatment with SBT should be used in patients presenting within the first hours after stroke.

Endovascular management of postoperative pseudoaneurysms of the external carotid artery.

Hemorrhage secondary to postoperative pseudoaneurysm is a rare event, but may complicate the clinical course of straightforward and common interventions such as sinonasal procedures, tonsillectomy, and maxillofacial and plastic surgeries. We report our experience with the endovascular management of iatrogenic pseudoaneurysm in eight patients who had undergone recent craniomaxillofacial surgery. Computed tomography (CT), including CT-angiography, detected only three of the eight lesions. In all patients, endovascular embolization achieved successful occlusion of the pseudoaneurysm without local or general procedure-related complications. Immediate proximal arterial occlusion with detachable coils was performed in every case, and pseudoaneurysm coiling was performed in three cases presenting with active hemorrhage. Endovascular therapy proved to be safe and effective in the management of postoperative pseudoaneurysms. Surgeons involved in the craniomaxillofacial procedures should be aware of this complication and its management.