Lyme Disease: What the Neuroradiologist Needs to Know

Lyme disease is the most common tick-borne disease in Canada and the United States, caused by Borrelia burgdorferi, which affects multiple organ systems. Epidemiology, clinical presentation, and neuroimaging findings are reviewed.

Appropriate use of CT perfusion following aneurysmal subarachnoid hemorrhage: a Bayesian analysis approach

BACKGROUND AND PURPOSE

In recent years CTP has been used as a complementary diagnostic tool in the evaluation of delayed cerebral ischemia and vasospasm. Our aim was to determine the test characteristics of CTP for detecting delayed cerebral ischemia and vasospasm in SAH, and then to apply Bayesian analysis to identify subgroups for its appropriate use.

MATERIALS AND METHODS

Our retrospective cohort comprised consecutive patients with SAH and CTP performed between days 6 and 8 following aneurysm rupture. Delayed cerebral ischemia was determined according to primary outcome measures of infarction and/or permanent neurologic deficits. Vasospasm was determined by using DSA. The test characteristics of CTP and its 95% CIs were calculated. Graphs of conditional probabilities were constructed by using Bayesian techniques. Local treatment thresholds (posttest probability of delayed cerebral ischemia needed to initiate induced hypertension, hypervolemia, and hemodilution or intra-arterial therapy) were determined via a survey of 6 independent neurologists.

RESULTS

Ninety-seven patients with SAH were included in the study; 39% (38/97) developed delayed cerebral ischemia. Qualitative CTP deficits were seen in 49% (48/97), occurring in 84% (32/38) with delayed cerebral ischemia and 27% (16/59) without. The sensitivity, specificity, and positive and negative predictive values (95% CI) for CTP were 0.84 (0.73-0.96), 0.73 (0.62-0.84), 0.67 (0.51-0.79), and 0.88 (0.74-0.94), respectively. A subgroup of 57 patients underwent DSA; 63% (36/57) developed vasospasm. Qualitative CTP deficits were seen in 70% (40/57), occurring in 97% (35/36) with vasospasm and 23% (5/21) without. The sensitivity, specificity, and positive and negative predictive values (95% CI) for CTP were 0.97 (0.92-1.0), 0.76 (0.58-0.94), 0.88 (0.72-0.95), and 0.94 (0.69-0.99), respectively. Treatment thresholds were determined as 30% for induced hypertension, hypervolemia, and hemodilution and 70% for intra-arterial therapy.

CONCLUSIONS

Positive CTP findings identify patients who should be carefully considered for induced hypertension, hypervolemia, and hemodilution and/or intra-arterial therapy while negative CTP findings are useful in guiding a no-treatment decision.

Cerebral infarction secondary to vasospasm after perimesencephalic subarachnoid hemorrhage

Perimesencephalic subarachnoid hemorrhage (pSAH) has been described as a distinct form of subarachnoid hemorrhage (SAH) associated with good outcomes. We report a 48-year-old female who developed cerebral infarction due to severe diffuse vasospasm following pSAH. The patient presented with non-aneurysmal pSAH and was discharged home on day 5. However, one week later she developed an acute onset of right hemiparesis. A brain MRI showed acute infarctions on diffusion weighted imaging and her cerebral angiogram showed diffuse vasospasm. The patient received intra-arterial diltiazem and hypervolemic-hypertensive-hemodilution therapy with resulting resolution of the vasospasm and hemiparesis. While not as common as in SAH, there is a potential for the occurrence of cerebral infarction due to vasospasm after pSAH.

Nebulized magnesium sulphate versus nebulized salbutamol in acute bronchial asthma: a clinical trial

Intravenous magnesium sulphate (MgSO4) has successfully been used in the treatment of acute asthma. The present study investigated the efficacy of nebulized MgSO4 as a bronchodilator in acute asthma as compared to nebulized salbutamol. This was a randomized, double-blind, controlled clinical trial. Asthmatics aged 12-60 yrs in acute exacerbation, with a peak expiratory flow (PEF) <300 L x min(-1), not having taken bronchodilators and not requiring assisted ventilation were included. Patients were randomized to receive treatment with serial nebulizations of either 3 mL (3.2% solution, 95 mg) MgSO4 solution or 3 mL (2.5 mg) salbutamol solution. All patients were also given 100 mg hydrocortisone i.v., and were monitored continuously for 2 h after which they were given supplemental treatment (if and when needed) and either discharged or admitted. Fischl index, PEF improvements (in % predicted) and admission rates were the outcome variables. Thirty-three patients were studied. Fischl score improvement was comparable and significant in both groups (4.31 to 0.43 in the MgSO4 group and 4.29 to 0.76 in the salbutamol group). The increase in PEF was statistically significant and comparable in both groups (by 35% pred in the MgSO4 and by 42% pred in the salbutamol group). Two patients warranted admission in the salbutamol group and one in the MgSO4 group. Nebulized MgSO4 had a significant bronchodilatory effect in acute asthma. This effect was not significantly different from that of nebulized salbutamol.

Long-term adrenalectomy decreases NMDA receptors in rat hippocampus

The effect of long-term adrenalectomy on NMDA receptors in the rat hippocampus was studied. Hippocampal sections of control and adrenalectomized rats were incubated with [3H]MK-801, a radiolabeled non-competitive inhibitor of the NMDA receptor. Analysis by in vitro autoradiography showed a significant decrease in [3H]MK-801 binding in the dentate gyrus, CA1 and CA4 areas, as well as the temporal cortex. Results of this study suggest that glucocorticoids are vital for the regulation of the NMDA receptors.

Retinal artery occlusion

A 54-year-old man presented with an acute painless loss of vision. He had a three-month history of malaise, weight loss, and episodic sweating. Physical examination showed a thin, febrile man with a petechial rash over the lower legs. Cardiac auscultation revealed an apical thrill and pansystolic murmur. Dental hygiene was poor. The diagnosis, mechanisms and treatment of retinal artery occlusion associated with bacterial endocarditis are reviewed.