Background

Computed tomography (CT) is the current standard for rapidly diagnosing some of the more common structural pathologies that affect the neurosurgical patient perioperatively. With this convenience comes the potential for its overuse.

Objective

To investigate the utility of head CT scans ordered for various clinical indications.

Methods

All head CT studies ordered by the UCLA Neurosurgery Department from August 15, 2011 through December 15, 2011, were prospectively studied. Variables collected included demographic information, diagnosis, surgical procedures, indication for CT, CT findings, and whether the study led to a documentable change in management.

Results

There were 801 head CT studies ordered for the 462 patients who were admitted to the neurosurgical service. The authors identified 14 indications for ordering a head CT with the following probabilities of a positive finding: examination change (17/56, 30.3%), follow-up (4-6 hours after intracerebral hemorrhage; 16/126, 12.7%), CT angiography (11/30, 36.7%), routine postoperative imaging (6/126, 4.7%), postventriculostomy placement (4/62, 6.5%), immediately before (4/31, 12.9%) or after removal of (2/42, 4.8%) a ventriculostomy, surveillance (>24 hours after intracerebral hemorrhage or external ventricular drain placement) (3/66, 4.5%), headaches (2/8, 25%), ground level fall (1/8, 12.5%), intracranial pressure spikes (2/6, 33.3%), and delayed (6-24 hours after intracerebral hemorrhage; 1/25, 4%).

Conclusion

The probability of discovering a clinically significant finding varies widely for each of the listed study indications. This prospective analysis of all CT scans ordered at a single institution suggests that imaging studies obtained without a change in neurological status were unlikely to produce a positive finding, and even when there was a positive finding, it was extremely unlikely to result in any intervention.

Objectives

Remote ischemic preconditioning (RIPC) is a powerful endogenous mechanism whereby a brief period of ischemia is capable of protecting remote tissues from subsequent ischemic insult. While this phenomenon has been extensively studied in the heart and brain in animal models, little work has been done to explore the effects of RIPC in human patients with acute cerebral ischemia. This study investigates whether chronic peripheral hypoperfusion, in the form of pre-existing arterial peripheral vascular disease (PVD) that has not been surgically treated, is capable of inducing neuroprotective effects for acute ischemic stroke.

Methods

Individuals with PVD who had not undergone prior surgical treatment were identified from a registry of stroke patients. A control group within the same database was identified by matching patient's demographics and risk factors. The two groups were compared in terms of outcome by NIH Stroke Scale (NIHSS), modified Rankin scale (mRS), mortality, and volume of infarcted tissue at presentation and at discharge.

Results

The matching algorithm identified 26 pairs of PVD-control patients (9 pairs were female and 17 pairs were male). Age range was 20-93 years (mean 73). The PVD group was found to have significantly lower NIHSS scores at admission (NIHSS≤4: PVD 47.1%, control 4.35%, p<0.003), significantly more favorable outcomes at discharge (mRS≤2: PVD 30.8%, control 3.84%, p<0.012), and a significantly lower mortality rate (PVD 26.9%, control 57.7%, p=0.024). Mean acute stroke volume at admission and at discharge were significantly lower for the PVD group (admission: PVD 39.6 mL, control 148.3 mL, p<0.005 and discharge: PVD 111.7 mL, control 275 mL, p<0.001).

Conclusion

Chronic limb hypoperfusion induced by PVD can potentially produce a neuroprotective effect in acute ischemic stroke. This effect resembles the neuroprotection induced by RIPC in preclinical models.

Background

Animal studies suggest that ischemic preconditioning prolongs coagulation times.

Objective

Because coagulation changes could hinder the translation of preconditioning into clinical settings where hemorrhage may be an issue, such as ischemic or hemorrhagic stroke, we evaluated the effects of remote ischemic preconditioning (RIPC) on coagulation in patients undergoing RIPC after aneurysmal subarachnoid hemorrhage (SAH).

Methods

Twenty-one patients with SAH (mean age, 56.3 years) underwent 137 RIPC sessions 2 to 12 days after SAH, each consisting of 3 to 4 cycles of 5 to 10 minutes of lower limb ischemia followed by reperfusion. Partial thromboplastin time (PTT), prothrombin time (PT), and international normalized ratio (INR) were analyzed before and after sessions. Patients were followed for hemorrhagic complications.

Results

No immediate effect was identified on PTT (mean pre-RIPC, 27.62 s; post-RIPC, 27.54 s; P = .82), PT (pre-RIPC, 10.77 s; post-RIPC, 10.81 s; P = .59), or INR (pre-RIPC, 1.030; post-RIPC, 1.034; P = .57) after each session. However, statistically significant increases in PT and INR were identified after exposure to at least 4 sessions (mean PT pre-RIPC, 11.33 s; post-RIPC, 12.1 s; P = .01; INR pre-RIPC, 1.02; post-RIPC, 1.09; P = .014, PTT pre-RIPC, 27.4 s; post-RIPC, 27.85 s; P = .092) with a direct correlation between the number of sessions and the degree of increase in PT (Pearson correlation coefficient = 0.59, P = .007) and INR (Pearson correlation coefficient = 0.57, P = .010). Prolonged coagulation times were not observed in controls. No hemorrhagic complications were associated with the procedure.

Conclusion

RIPC by limb ischemia appears to prolong the PT and INR in human subjects with SAH after at least 4 sessions, correlating with the number of sessions. However, values remained within normal range and there were no hemorrhagic complications.