Ultrasound measurement of optic nerve sheath diameter pre- and post-lumbar puncture

Optic nerve sheath diameter measurement for prediction of postdural puncture headache

PURPOSE

Intracranial hypotension due to cerebrospinal fluid leak is mainly the causal factor for the pathophysiology of postdural puncture headache (PDPH). In this study, we aimed to evaluate the effectiveness of optic nerve sheath diameter (ONSD) measurement in predicting the development of PDPH in patients undergoing spinal anesthesia.

METHODS

According to the American Society of Anesthesiology (ASA) physical classification I-III, 83 patients aged 18-65 years scheduled for spinal anesthesia for elective surgery were included in the study. Demographic data (age, ASA, sex, smoking, migraine, and PDPH history) and operative data were recorded. Preoperative ONSD measurements were taken in the right and left eye, axial, and sagittal planes. The mean of four measurements was recorded before and 24 h after the spinal anesthesia.

RESULTS

A total of 83 patients (59 males and 24 females) were included in the study. In our study, the rate of PDPH development was determined as 22.9% (n = 19). There was a statistically significant difference in the preoperative and postoperative ONSD values between patients with and without PDPH development (p = 0.046). In the receiver operating characteristic analysis, the area under the curve was 0.843, and the cutoff value was 0.4.

CONCLUSION

The difference between the ONSD values measured before and after spinal anesthesia may be an important parameter for predicting the risk of PDPH development.

Characterization of Ocular Sonography Findings and their Relationship to Clinical Features from a South Indian Cohort of Idiopathic Intracranial Hypertension

Background

Idiopathic intracranial hypertension (IIH) typically manifests with headache, accompanied by papilledema and visual loss, and has a higher prevalence in females. In recent years, ocular sonography, particularly, measurement of optic nerve sheath diameter (ONSD), is being investigated for diagnosis of IIH.

Methods

A total of 35 patients over the age of 18 years, fulfilling the modified Dandy's criteria for diagnosis of IIH were included. Patients underwent assessment with magnetic resonance imaging, lumbar puncture, and ocular sonography to measure ONSD and ocular arterial indices.

Results

The mean ONSD values (in centimeters) in the right eye of patients with IIH was 0.57 ± 0.13, while it was 0.48 ± 0.03 in controls. In the left eye, the mean ONSD value (cm) was 0.59 ± 0.13 in patients with IIH and 0.48 ± 0.03 in controls. ONSD was significantly higher in cases compared to controls (P < 0.001, Welch test). Pulsatility index of the central retinal artery was significantly higher in cases compared to controls (P < 0.001, Welch test). Resistance index of the ophthalmic artery was statistically significant (P < 0.005, Welch test). Receiver operating characteristic curve analysis revealed a cutoff value of 5.1 mm on the right side and 5 mm on the left side had a sensitivity and specificity of more than 80% for IIH diagnosis.

Conclusion

Our study provides insights into the utility of optic nerve sheath measurements and arterial indices in the diagnosis of IIH in a South Indian cohort. Further research is needed to fully understand the longitudinal relationship of these parameters and treatment outcomes in IIH.

Perioperative Variation in Optic Nerve Sheath Diameter - A Prospective Observational Study of Traumatic Brain Injury Patients Undergoing Decompressive Craniectomy

Background

Measuring optic nerve sheath diameter (ONSD) by transbulbar ultrasonography (TBUS) can suffice non-invasive ICP measurement with considerable accuracy.

Objective

The primary objective of this study was to evaluate the perioperative variation in ONSD by TBUS in Traumatic Brain Injury (TBI) patients undergoing emergency craniectomy.

Methods

We prospectively compared bilateral ONSD measurements in 45 consecutive TBI cases undergoing decompressive craniectomy under general anesthesia; before and after surgery. A total of 180 ONSD images were obtained and measurements were done by the same investigator blinded to the pre/postoperative nature of the image.

Results

Based on preoperative Glasgow Coma Scores, 34 cases (75.5%) had severe TBI; 10 cases (22.2%) moderate TBI; and 1 case (2.2%) mild TBI. Preoperative ONSD in the study population were as 6.625 ± 0.414mm. Average ONSD reduced significantly by 0.249 ± 0.148 mm (P < 0.001) after craniectomy. On pooled analysis of cases undergoing right versus left sided craniectomy average ONSD reduced significantly by 0.252 ± 0.173 mm (P < 0.001) and 0.259 ± 0.139 mm (P < 0.001), respectively. ONSD of right eye with left eye and vice-versa were strongly correlated both pre/postoperatively with Pearson correlation coefficients (r)=0.879 (P < 0.001) and r = 0.827 (P < 0.001), respectively.

Conclusions

In TBI cases undergoing decompressive craniectomy ONSD is bilaterally increased preoperatively. ONSD reduces significantly immediately after craniectomy; however, the diameters did not near the normal range. There hold a strong correlation between right/left ONSD measurements irrespective of the laterality of injury or side of surgery. Variable elastic properties of ONS in an injured brain can possibly explain our findings.