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Updated: May 5, 2026
P50 Sensory Gating in Infants
Published on: December 26, 2013
Positive sharp waves in the EEG of children and adults
A Bruce Janati1, Muhammad Umair, Naif Saad Alghasab
1Center for Neurology in Fairfax, Fairfax, VA, USA, brucejanatimd@aol.com.
Insights
Positive sharp waves (PSWs) on EEG are an under-reported epileptogenic pattern, especially in younger patients. PSWs strongly associate with chronic central nervous system (CNS) pathology, particularly congenital anomalies.
Area of Science:
- Neurology
- Neurophysiology
- Pediatric Neurology
Background:
- Interictal epileptiform discharges (IEDs) are well-studied, but positive sharp waves (PSWs) remain under-reported.
- PSWs are a type of IED with positive polarity observed in scalp electroencephalography (EEG).
Purpose of the Study:
- To investigate the pathophysiological, neuroimaging, and clinical correlates of positive sharp waves (PSWs) in a diverse patient population.
- To determine the significance and localizing value of PSWs in EEG.
Main Methods:
- Prospective review of 1,250 EEGs over one year.
- Analysis of EEG parameters, demographic, clinical, and neuroimaging data for 31 patients with PSWs.
- Statistical correlation of clinical and EEG findings.
Main Results:
- PSWs are an epileptogenic pattern with localizing significance, more common in younger individuals.
- A strong association exists between PSWs and chronic/static central nervous system (CNS) pathology, especially congenital anomalies.
- Multifocal PSWs are linked to severe intellectual and motor deficits, often due to congenital CNS insults.
Conclusions:
- PSWs are a rare EEG abnormality indicating focal epileptogenicity, similar to negative IEDs.
- The presence of PSWs warrants neuroimaging to identify underlying chronic CNS pathology, particularly congenital anomalies.
- Multifocal PSWs suggest severe developmental deficits and underlying congenital CNS insults.
Abstract:
Interictal epileptiform discharges (IEDs) with negative polarity have been extensively studied in the EEG literature. However, little attention has been drawn to IED with positive polarity [positive sharp waves (PSWs)]. In this paper, we discuss pathophysiological, neuroimaging, and clinical correlates of this pattern in a heterogeneous group of children and adults who demonstrated PSW in their scalp EEG. We prospectively reviewed the EEGs of 1,250 patients from a heterogeneous population over a period of 1 year. Thirty-one patients had PSW in their EEG. We documented EEG parameters as well as demographic, clinical, and neuroimaging data. Statistical analysis was performed to correlate the aforementioned data. The analysis showed that PSW is an epileptogenic pattern with localizing significance, occurring primarily in the younger age groups. Furthermore, there was a strong association of PSW with chronic and/or static CNS pathology, in particular, congenital CNS anomalies, often accompanied by psychomotor retardation. Patients with "multifocal'' PSW invariably exhibited severe intellectual and motor deficits associated consistently with a variety of congenital CNS insults. PSW is a rare and under-reported EEG abnormality which, similar to negative IED, signifies focal epileptogenecity. The presence of PSW should prompt neuroimaging studies to investigate an associated chronic/static CNS pathology, in particular, congenital CNS anomalies. This association is particularly strong when PSW is multifocal in which case patients present with severe intellectual and motor deficits.
