Measuring changes in the optic nerve sheath diameter in patients with idiopathic normal-pressure hydrocephalus: a useful diagnostic supplement to spinal tap tests.

BACKGROUND AND PURPOSE: Cerebrospinal fluid (CSF) removal improves clinical symptoms of many patients with idiopathic normal-pressure hydrocephalus (iNPH). The aim of this study was to investigate the correlation of changes in the optic nerve sheath diameter (ONSD) with patient responses to CSF removal. METHODS: Transorbital ultrasonography was performed to obtain ONSD measurements in 31 patients with iNPH before and after lumbar puncture. Measurements were obtained while patients were supine and upright. Changes in the ONSD between supine and upright positions [ONSD variability (ONSD-V)] were assessed and compared with those in 60 healthy volunteers. ONSD-V was correlated with relative changes in a validated iNPH severity (Boon) score. RESULTS: Mean pre-puncture ONSD-V was significantly lower in healthy volunteers and patients with no response to CSF removal (Fisher test) [0.05 ± 0.14 mm (SD)] than in responsive patients [0.37 ± 0.20 mm (SD), P < 0.001]. ONSD-V predicted response to the spinal tap test (odds ratio, 0.30; 95% confidence interval, 0.12-0.75 mm, P = 0.011). The higher the ONSD-V, the better the therapeutic effect (χ2 = 14.980, P < 0.001). The post-spinal tap test ONSD-V correlated significantly with clinical severity in the motor portion of the Boon score [0.16 ± 0.23 mm (SD), P = 0.003]. CONCLUSIONS: The ONSD-V before and after spinal tap test correlated well with the clinical effects of CSF removal. Transorbital ultrasonography seems to be a reliable, safe add-on to the Fisher test and may support selection of patients for shunt intervention.

A new methodological approach to the study of habituation: the use of positive and negative behavioral indices of habituation.

This report details a new method to measure habituation in an open-field. In addition to the measurement of spontaneous locomotor activity, time spent per visit to the center zone (CZ) is also measured. Critically, a small object is placed in the CZ to modulate an animal's investigatory response. When an animal is first exposed to the open-field, the presence of the object does not affect the duration of its visits to the CZ but, if the animal is given one additional 10-min exposure to the open-field, then the presence of the object substantially increases the duration of its visits to the CZ. The presence of the object, however, has no effect on the rat's locomotor activity. Thus, habituation could be observed by two different measures: a decrease in locomotor activity and an increase in an animal's investigatory response to a stimulus object. A basic problem with a reliance solely upon a decrease in locomotor activity to measure habituation is that it represents a negative change in behavior. The present method circumvents this shortcoming by incorporating a positive behavioral measure of habituation in conjunction with the measurement of locomotor activity. This modification of the open-field test offers substantial utility for studies of neurotoxicology and memory because one can assess concurrently treatment effects on motor activity, attention to an object and memory.

The NMDA receptor and cocaine: evidence that MK-801 can induce behavioral sensitization effects.

Antagonism of the NMDA receptor with MK-801 is considered to be an effective pharmacologic manipulation to prevent the development of sensitization effects to drugs such as cocaine. The present study investigated this issue by comparing the behavioral response of separate groups of rats to three treatment cycles of either saline, 0.1 mg/kg MK-801, 10 mg/kg cocaine, or combined MK-801-cocaine (0.1/10 mg/kg). The treatments were spaced 1 week apart and were preceded by two nondrug baseline tests. In the first test cycle, the four groups had equivalent activity levels in the two nondrug tests. In the first drug test only the MK-801-cocaine group exhibited hyperactivity. By the third drug test, the MK-801-cocaine group exhibited an enhanced hyperactivity and the MK-801 group became hyperactive. Thus, behavioral drug sensitization developed but only with groups treated with MK-801. Antagonism of the NMDA receptor under some circumstances can be a highly effective treatment for the induction of behavioral sensitization effects.