Related Experiment Video
Updated: Apr 5, 2026

06:15
Zebra II as A Novel System to Record Electrophysiological Signals in Zebrafish
Published on: August 16, 2024
933
The zebra sign: an unknown known.
A Nagendran1, B Patel1, U Khan1
1Department of Neurology, St George's Hospital NHS Foundation Trust, Tooting, UK.
Practical Neurology
|August 15, 2015
Summary
A patient developed remote cerebellar hemorrhage and convexity subarachnoid hemorrhage after laminectomy. This case highlights potential mechanisms for these rare post-operative neurological complications.
Area of Science:
- Neurosurgery
- Neurology
- Radiology
Background:
- Laminectomy is a common spinal surgery.
- Postoperative neurological complications can occur, though rare.
Observation:
- A 65-year-old woman presented with obtundation after a routine laminectomy.
- Imaging revealed bilateral cerebellar hemorrhage and convexity subarachnoid hemorrhage.
Findings:
- The patient exhibited signs consistent with remote cerebellar hemorrhage (RCH).
- Convexity subarachnoid hemorrhage (cSAH) was also noted.
- The 'zebra sign' was observed, a pattern associated with RCH.
Implications:
- Discusses potential pathophysiological mechanisms for RCH and cSAH post-surgery.
- Emphasizes the importance of recognizing these rare but serious neurological events.
- Suggests further investigation into the link between spinal surgery and these specific hemorrhages.
Related Concept Videos
Introduction to the Sign Test
1.5K
The sign test is an important tool in nonparametric statistics, offering a straightforward yet effective method for analyzing matched pairs, nominal data, or hypotheses concerning the median of a population. It transforms data points into positive or negative signs, avoiding the need for assumptions about data distribution and instead focusing on the direction of change. It is particularly valuable when data does not conform to the normal distribution requirements of many parametric tests. For...
1.5K
Sign Test for Nominal Data
450
The sign test is a nonparametric method used to evaluate hypotheses about the median of a single sample or to compare the medians of two related samples. The sign test is particularly useful when dealing with nominal data, which includes distinct categories without an inherent order, such as names, labels, and preferences. Nominal data restricts statistical analysis to evaluating population proportions rather than mean or median values that require continuous data.
For example, consider a...
For example, consider a...
450
Sign Test for Matched Pairs
471
The sign test for matched pairs offers a robust method for comparing two paired samples, often for the effects of an intervention in one of them. This method is very useful in situations where the underlying distribution of the data is unknown. The test compares two related samples—often pre- and post-treatment measurements on the same subjects—to determine if there are significant differences in their median values.
To conduct the sign test, we first calculate the differences in...
To conduct the sign test, we first calculate the differences in...
471
Sign Test for Median of Single Population
424
In general, the sign test serves as a nonparametric method to test hypotheses about the median of a single population when the data does not follow a known distribution. This simplicity makes it particularly useful for small sample sizes or when the assumptions of parametric tests cannot be met. The process begins with identifying a null hypothesis, typically stating that the population median equals a specific value. The alternative hypothesis could be that the median is either not equal to,...
424

