Transcranial Doppler for evaluation of idiopathic intracranial hypertension

Establishing continuum in Transcranial Doppler characteristics of IIH, migraine and healthy controls- An exploratory study

BACKGROUND

IIH is a severe form of headache that often has superimposed migraine and often it is very difficult to distinguish the two forms of headache. Intracranial hemodynamics is a relatively unexplored means of distinguishing between the two forms of headache.

OBJECTIVES

We aimed to study intracranial flow dynamics using Transcranial Doppler in patients with IIH, migraine, and normal controls.

MATERIALS AND METHODS

It was a hospital-based observational study that included 51 people with IIH, 87 people with migraine, and 101 healthy controls and all were subjected to TCD study after detailed clinical examination.

RESULTS

Mean age of patients in three groups were similar with the mean age in IIH being 33.41 ± 10.75 (age in years ± SD). Vision loss was present in 66.67% of patients with IIH, and most common field defect was generalized constriction (27.5%). Neuroimaging was abnormal in 94.11% of patients of IIH with mean CSF pressure was 31.27±5.32 cm of water. Of all the TCD-measured velocities, mean flow velocity (MFV) showed a significant difference in all three groups with (p-value <0.001). The pulsatility index, both for middle cerebral arteries as well as ophthalmic arteries showed a significant difference in the three groups with the highest values in IIH patients (p-value<.001). The mean VMR in IIH (1.11±0.32) was lower than the mean VMR in migraine (1.34±0.43) as well as controls (1.49±0.46).

CONCLUSION

TCD parameters like MFV and PI are useful parameters that show considerable variation and can be used to differentiate between IIH and migraine.

Evaluation of cerebrovascular hemodynamics in patients with idiopathic intracranial hypertension using transcranial Doppler

Background

Idiopathic intracranial hypertension (IIH) is a disorder of increased intracranial pressure without a clear cause and can have serious visual effects. Previous research work suggests that transcranial Doppler measurements of pulsatility index correlate accurately with elevated intracranial pressure.

Objective

To assess the cerebrovascular hemodynamic changes in patients with IIH using transcranial Doppler before and after lumbar puncture and CSF withdrawal.

Methods

An interventional study conducted on 40 patients (31 females and 9 males) fulfilling the modified Dandy criteria for diagnosis of idiopathic intracranial hypertension, MRI brain, and MRV was done to the patients. Lumbar puncture was done for all included patients to measure intracranial pressure and CSF withdrawal. Transcranial Doppler was performed for all included before and after lumbar puncture and CSF withdrawal and the following parameters were measured: peak systolic velocity (PSV), end diastolic velocity (EDV), resistivity index (RI), and pulsatility index (PI).

Results

Significant relation was found between grades of papilledema and PSV, RI, and PI (p value 0.012, 0.025, 0.016) but no significant relation was found between grades of papilledema and EDV (0.102). Significant changes occurred in parameters of TCD pre- and post-CSF withdrawal including PSV, EDV, and PI (p value 0.001, 0.015, 0.019) denoting a significant change in cerebral hemodynamics after CSF withdrawal which denotes a decrease in intracranial pressure.

Conclusion

Increased intracranial pressure significantly affects cerebral blood flow. A normalization of transcranial Doppler parameters occurs following lowering of intracranial pressure through lumbar puncture and CSF withdrawal.

Transcranial Doppler for Monitoring and Evaluation of Idiopathic Intracranial Hypertension

Background  Idiopathic intracranial hypertension (IIH) is a disorder of unknown origin, characterized by features of raised intracranial pressure (ICP). Existing literature is inconclusive about the role of transcranial Doppler (TCD) in the management of IIH. Objective  To study the TCD changes in IIH patients, pre- and post-cerebrospinal fluid (CSF) drainage. Materials and Methods  This was a prospective study, conducted between July 2017 and December 2019, in a tertiary care referral center in South India. Sixteen consecutive patients, suspected to have IIH, underwent magnetic resonance imaging ofthe brain, a baseline TCD, and lumbar puncture with CSF drainage and pressure monitoring. Post-CSF drainage, TCD was repeated and mean flow velocities, peak systolic velocities, end-diastolic velocities, and pulsatility index (PI), in the middle cerebral artery (MCA), vertebral artery, and basilar artery (BA) were noted. Thirteen patients had elevated CSF pressure, and fulfilled the diagnostic criteria for IIH. These patients were included in the final analysis and pre- and post-CSF drainage TCD blood flow velocities and PI were compared. Results  The mean age of study participants was 29.92 ± 6.92 years. There was a significant reduction in the cerebral flow velocities in bilateral MCA, after CSF drainage and normalization of ICP. Flow velocities in posterior circulation and PI in MCA, PCA, and BA showed an insignificant reduction. Two patients, who did not show any reduction in flow velocities after CSF drainage, developed optic atrophy on follow-up. Conclusion  TCD-derived systolic blood flow velocities can be used in the management and follow-up of patients with IIH.

TCD Diastolic Velocity Decay and Pulsatility Index Increment in PVS Cases

Background:

Functional neuroimaging has provided new insights for assessing cerebral function in persistent vegetative state patients (PVS). Compared to controls, positron emission tomography and single photon emission tomography have shown a substantial reduction of global brain cerebral glucose metabolism and perfusion in PVS. Doppler ultrasonography (TCD) assesses local blood flow velocity and direction in the proximal portions of large intracranial arteries; it is a noninvasive technique, and it can be carried out at the bedside. To date, few studies have applied TCD to study PVS.

Methods:

We assessed intracranial circulation by TCD in five PVS patients. The cause of brain insult was hypoxic encephalopathy in four cases, and the other suffered an embolic cerebral infarct causing a top of the basilar artery syndrome. The sample volume was set at 12 mm; power output and gain settings were maximized as needed. The temporal bone acoustic window was not suitable for intracranial vessel insonation in all patients. As an alternative, the internal carotid artery siphon was assessed by orbital insonation between 55-70 mm.

Results:

Systolic velocity was within a normal range, between 44 and 62 cm/second in all cases. However, the diastolic amplitude was reduced, as well as the end diastolic velocity, and the pulsatility index was increased in all patients.

Conclusions:

We conclude that TCD diastolic velocity decrement and PI augmentation in our cases might be related to uncoupling of cerebral blood flow and cerebral metabolic rate, arising from reduced cerebral glucose consumption and oxygen uptake, after extensive brain injury.

Automated Cross-Sectional Measurement Method of Intracranial Dural Venous Sinuses

BACKGROUND AND PURPOSE

MRV is an important blood vessel imaging and diagnostic tool for the evaluation of stenosis, occlusions, or aneurysms. However, an accurate image-processing tool for vessel comparison is unavailable. The purpose of this study was to develop and test an automated technique for vessel cross-sectional analysis.

MATERIALS AND METHODS

An algorithm for vessel cross-sectional analysis was developed that included 7 main steps: 1) image registration, 2) masking, 3) segmentation, 4) skeletonization, 5) cross-sectional planes, 6) clustering, and 7) cross-sectional analysis. Phantom models were used to validate the technique. The method was also tested on a control subject and a patient with idiopathic intracranial hypertension (4 large sinuses tested: right and left transverse sinuses, superior sagittal sinus, and straight sinus). The cross-sectional area and shape measurements were evaluated before and after lumbar puncture in patients with idiopathic intracranial hypertension.

RESULTS

The vessel-analysis algorithm had a high degree of stability with <3% of cross-sections manually corrected. All investigated principal cranial blood sinuses had a significant cross-sectional area increase after lumbar puncture (P ≤ .05). The average triangularity of the transverse sinuses was increased, and the mean circularity of the sinuses was decreased by 6% ± 12% after lumbar puncture. Comparison of phantom and real data showed that all computed errors were <1 voxel unit, which confirmed that the method provided a very accurate solution.

CONCLUSIONS

In this article, we present a novel automated imaging method for cross-sectional vessels analysis. The method can provide an efficient quantitative detection of abnormalities in the dural sinuses.

OCT assessment of morphological changes of the optic nerve head and macula in idiopathic intracranial hypertension

OBJECTIVE

To assess the morphologic changes of the optic nerve head and macula in patients with idiopathic intracranial hypertension (IIH) with optical coherence tomography (OCT).

METHODS

Data was extracted from the medical records and Stratus OCT images of IIH patients.

RESULTS

Ninety-one eyes of 48 IIH patients were divided into 3 groups according to their clinical optic disc appearance. Average retinal nerve fiber layer (RNFL) thickness was statistically different between the groups: normal optic disc/mild elevation group (N=20) - 89 μm (95% CI, 80-98 μm), mild elevation group (N=51) - 109 μm (95% CI, 101-117 μm), and papilledema group (N=20) 124 μm (95% CI, 100-153 μm) (P=0.004). Fast macular thickness map did not demonstrate a significant difference between the groups for most measured macular areas (N=49 eyes).

CONCLUSIONS

Peripapillary RNFL measurements correlated with the clinical appearance of the optic discs, suggesting that OCT may assist in the follow up of IIH patients.

Utility of transcranial doppler in idiopathic intracranial hypertension

INTRODUCTION

Idiopathic intracranial hypertension (IIH) can be an elusive diagnosis, and poor visual outcomes may occur. Currently, the only means of accurately diagnosing and following these patients is with repeated lumbar puncture. Previous work has shown that transcranial doppler measurements of pulsatility correlate accurately with elevated intracranial pressure (ICP). This study is designed to assess whether pulsatility index (PI) correlates with ICP in patients newly diagnosed with IIH.

METHODS

Seven patients with clinical suspicion of IIH were included in this study. Clinical suspicion was based on history of recurrent headaches and papilledema. All patients had otherwise normal examinations and imaging. Middle cerebral arteries were insonated to obtain average PI values. Cerebrospinal fluid (CSF) was then withdrawn, and closing pressures were recorded. Pulsatility index values were then obtained again, within ten minutes after completing CSF withdrawal. PI values were correlated with ICP values, and pre and post CSF withdrawal values were compared.

RESULTS

All seven patients had elevated opening pressures (average 39 cm H2O, range 27-70). The average closing pressure after approximately 30 cc of CSF withdrawal was 11.9 cm H2O. The average PI before CSF withdrawal was 0.95, which dropped to 0.70 after CSF withdrawal (p = 0.02). The change in ICP was found to be correlated with a change in PI (p = 0.004).

CONCLUSIONS

These findings suggest that PI may be useful for following patients with IIH non-invasively. Further study with larger groups and blinded assessments should be useful in better characterizing the accuracy of this technique.

New transcranial Doppler index in infants with hydrocephalus: transsystolic time in clinical practice

Raised intracranial pressure (ICP) in infants with hydrocephalus may cause (ir)reversible damage to the brain parenchyma but can be present without clinical signs and/or symptoms. Therefore, new, favorably noninvasive, detection methods are needed to distinguish between compensated hydrocephalus with normal intracranial pressure and slowly progressive hydrocephalus with increased intracranial pressure. Because early ischemic changes in the brain parenchyma are associated with increased intracranial pressure, transcranial Doppler (TCD) indices may be useful to detect increased intracranial pressure in infants with hydrocephalus. Twenty-four infants with hydrocephalus underwent noninvasive ICP measurement, magnetic resonance imaging and TCD before and after cerebrospinal fluid (CSF) diversion. The TCD indices were paired to the anterior fontanelle pressure findings and compared for correlation. After CSF diversion, ICP decreased significantly from 21.8 cm H(2)O to 7.7 cm H(2)O (p<0.005). The transsystolic time (TST) as measured with TCD increased significantly from 176 to 221 ms (p<0.005), whereas the pulsatility index (PI) decreased significantly from 1.3 to 1.0 (p<0.05). The resistance index (RI) decreased significantly from 0.73 to 0.63 (p<0.05). Mean bloodflow velocity through the middle cerebral artery increased significantly from 55.5 to 75.8 cm/s (p<0.005). TST has a strong correlation with the ICP (p<0.005). Measuring TST with TCD can be helpful in the decision-making process about whether to perform CSF diversion in infants with hydrocephalus. Because TST is related solely to the relative changes in the flow velocity caused by intracranial physical properties, it has a closer relation to ICP than the PI and the RI.

Advances in evaluation and management of pediatric idiopathic intracranial hypertension

PURPOSE OF REVIEW

Although the demographics of pediatric idiopathic intracranial hypertension have been well described, the best approaches to its management are less well defined. Recent advances in evaluation of optic nerve status make it easier to determine when and if more aggressive intervention is required. Medical and surgical approaches are discussed.

RECENT FINDINGS

Modern neuroimaging techniques are used to look for secondary causes of intracranial hypertension such as cerebral venous sinus thrombosis. Automated perimetry is now quicker to perform and is accepted as the gold standard in evaluating optic nerve defects, even in the pediatric population. Other newer techniques for assessing optic nerve injury include optical coherence tomography, laser scanning tomography, and spectral Doppler blood flow analysis of the optic nerve head. Medical management remains the first-line treatment, but increasingly, surgical interventions such as optic nerve sheath fenestration and cerebrospinal fluid shunting are used in the pediatric population.

SUMMARY

Pediatric intracranial hypertension patients may be followed with a greater degree of precision than in the past. Management tends to be similar to that used in adults, now including surgical intervention when indicated. The newer technologies allow us to gather data that may help to determine the optimal time for surgical intervention for those patients who require it.