Focal Areas of High Signal Intensity in Children with Neurofibromatosis Type 1: Expected Evolution on MRI

BACKGROUND AND PURPOSE

Focal areas of high signal intensity are T2WI/T2-FLAIR hyperintensities frequently found on MR imaging of children diagnosed with neurofibromatosis type 1, often thought to regress spontaneously during adolescence or puberty. Due to the risk of tumor in this population, some focal areas of high signal intensity may pose diagnostic problems. The objective of this study was to assess the characteristics and temporal evolution of focal areas of high signal intensity in children with neurofibromatosis type 1 using long-term follow-up with MR imaging.

MATERIALS AND METHODS

We retrospectively examined the MRIs of children diagnosed with neurofibromatosis type 1 using the National Institutes of Health Consensus Criteria (1987), with imaging follow-up of at least 4 years. We recorded the number, size, and surface area of focal areas of high signal intensity according to their anatomic distribution on T2WI/T2-FLAIR sequences. A generalized mixed model was used to analyze the evolution of focal areas of high signal intensity according to age, and separate analyses were performed for girls and boys.

RESULTS

Thirty-nine patients (ie, 285 MR images) with a median follow-up of 7 years were analyzed. Focal areas of high signal intensity were found in 100% of patients, preferentially in the infratentorial white matter (35% cerebellum, 30% brain stem) and in the capsular lenticular region (22%). They measured 15 mm in 95% of cases. They appeared from the age of 1 year; increased in number, size, and surface area to a peak at the age of 7; and then spontaneously regressed by 17 years of age, similarly in girls and boys.

CONCLUSIONS

Focal areas of high signal intensity are mostly small (<15 mm) abnormalities in the posterior fossa or capsular lenticular region. Our results suggest that the evolution of focal areas of high signal intensity is not related to puberty with a peak at the age of 7 years. Knowledge of the predictive evolution of focal areas of high signal intensity is essential in the follow-up of children with neurofibromatosis type 1.

Phosphoinositide 3-kinase gamma: a key modulator in inflammation and allergy

Chronic inflammation and allergy involve the activation of tissue-resident cells and, later on, the invasion of effector cells. We have previously shown that the loss of phosphoinositide 3-kinase (PI3K) gamma impairs chemokine-dependent migration of neutrophils and macrophages both in vitro and in vivo. On the other hand, PI3K gamma is not required either during phagocytic processes or in the activation of bactericidal activities like granule secretion and particle-mediated respiratory burst in neutrophils. Tissue mast cells are key regulators in allergy and inflammation and release histamine upon clustering of their IgE receptors. We have demonstrated that murine mast cell responses are exacerbated in vitro and in vivo by autocrine signals, and require functional PI3K gamma. Adenosine, acting through the A(3) adenosine receptor, as well as other agonists of G(alpha i)-coupled receptors, transiently increased PtdIns(3,4,5) P (3) exclusively via PI3K gamma. PI3K gamma-derived PtdIns(3,4,5) P (3) was instrumental for initiation of a sustained influx of external Ca(2+) and degranulation. Mice that lacked PI3K gamma did not form oedema when challenged by passive systemic anaphylaxis. PI3K gamma thus relays inflammatory signals through various GPCRs, and is thus central to mast cell function. Taken together, this suggests that pharmaceutical targeting of PI3K gamma might alleviate inflammation at both early and late stages of the allergic response.

Resistance to thromboembolism in PI3Kgamma-deficient mice

Platelet aggregation and subsequent thrombosis are the major cause of ischemic diseases such as heart attack and stroke. ADP, acting via G protein-coupled receptors (GPCRs), is an important signal in thrombus formation and involves activation of phosphoinositide 3-kinases (PI3K). When platelets from mice lacking the G protein-activated PI3Kgamma isoform were stimulated with ADP, aggregation was impaired. Collagen or thrombin, however, evoked a normal response. ADP stimulation of PI3Kgamma-deficient platelets resulted in decreased PKB/Akt phosphorylation and alpha(IIb)beta(3) fibrinogen receptor activation. These effects did not influence bleeding time but protected PI3Kgamma-null mice from death caused by ADP-induced platelet-dependent thromboembolic vascular occlusion. This result demonstrates an unsuspected, well-defined role for PI3Kgamma downstream of ADP and suggests that pharmacological targeting of PI3Kgamma has a potential use as antithrombotic therapy.

A 24-month, double-blind, placebo-controlled multicentre pilot study of the efficacy and safety of nicergoline 60 mg per day in elderly hypertensive patients with leukoaraiosis

In this pilot study, 72 non-demented and non-depressive elderly hypertensive patients with evidence of leukoaraiosis on cerebral computed tomography scan (Rezek score: > 16) were randomly assigned to receive either nicergoline 30 mg b.i.d. (n = 36) or a placebo (n = 36) for 24 months. All patients received antihypertensives and their hypertension was controlled under treatment. They were evaluated by nine neuropsychological tests exploring memory, concentration, verbal and motor performances, administered at baseline and at every six-month interval during the study period. At baseline, the two groups were comparable for all demographic and clinical characteristics, including cognitive functions, except for the delayed recall of the Auditory Verbal Learning Test (AVLT), which was better in the placebo group (P = 0.04). Changes in scores over time were compared between the two groups. At the last visit, patients on nicergoline (n = 31) were found to have deteriorated less or to have improved more on test scores than the patients on placebo (n = 30). Significant differences were observed for memory function (AVLT short term recall, P = 0.026; AVLT delayed recall, P = 0.013; and, Benton Visual Retention Test, P = 0.002) and attention and concentration (Letter Cancellation Test, P = 0.043; and, WAIS-R Digit Symbol subtest, P = 0.006). The Rezek score remained unchanged in the two groups. Tolerance of nicergoline was similar to that of placebo. In conclusion, this study shows that nicergoline 30 mg b.i. d. administered over a 24-month period attenuates the deterioration in cognitive functions in elderly hypertensive patients with leukoaraiosis. Whether these effects were specific for this type of white matter changes could not be determined in the context of this pilot study.

Use of a microprocessor-equipped tablet box in monitoring compliance with antihypertensive treatment

Compliance with antihypertensive therapy is usually monitored by questionnaire, tablet counts, or estimation of drug levels in blood or in urine. The aim of this study was to examine patient compliance by means of an "electronic monitor." After 2 weeks of run-in on placebo, 34 moderately hypertensive patients were included in an open, randomized, crossover trial examining the efficacy and tolerance of nitrendipine, 20 mg as a single daily dose (morning or evening) for 1 month. We analyzed the results in 26 patients. Patients were supplied with tablet boxes equipped with a microprocessor (MENS) that registered the timing and duration of opening of the box over both the placebo and nitrendipine periods. Compliance (%) was calculated as the ratio of the number of days that the pill box was opened to the number of days between visits. The compliance was analyzed for each treatment group, namely placebo and nitrendipine morning and evening, over 1 month. Compliance (mean + SD) was 96.5 +/- 7.4% on placebo and 94.4 +/- 10.7% in the morning and 90.6 +/- 15.4% in the evening. Nitrendipine was taken in the morning at 0700 h +/- 2 h and in the evening at 1859 h +/- 2 h 12 min. The frequency of 24 h +/- 1 h intervals between medication was 83.5% on placebo. This frequency was 72.6% for morning dosage and 71.8% for evening dosage on nitrendipine. There were no differences in compliance between the morning and evening groups when analyzed according to age and sex. There was a negative correlation with time (r = -0.57, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)