99Tcm-HMPAO brain SPET in patients with pseudotumour cerebri

Transverse sinus pathologies, vestibular migraine and intracranial hypertension without papilledema

BACKGROUND

In the absence of papilledema, the presentation of migraine and idiopathic intracranial hypertension (IIH) is very similar. In this respect, an IIH could be presented as a vestibular migraine. Our main objective in this case report is to demonstrate the similarities between IIH and vestibular migraine.

CASES

This is a report of 14 patients who have IIH without papilledema presented as vestibular migraine to the clinic and followed from 2020 to 2022.

RESULTS

The common presentation of patients was ear-facial pain, dizziness, and frequent pulsatile tinnitus. One-fourth of the patients reported episodes of true episodic vertigo. The average age was 37.8, the average BMI was 37.4, and the average lumbar puncture-opening pressure was 25.6 cm H2O. Transverse sinus venous flow alterations caused neuroimaging findings of sigmoid sinus dehiscence, empty sella, or tonsillar ectopia. Most patients improved with carbonic anhydrase inhibitors, and one patient was treated with a dural sinus stent.

CONCLUSION

A transverse sinus stenosis, even in the non-dominant site, may elevate the CSF pressure in obese individuals. This stenosis causes dural sinus-related pulsatile tinnitus with characteristics different from those of an arterial origin. Dizziness is a common complaint in patients with IIH, just like VM. In our opinion, episodic vertigo in these patients is the direct effect of CSF flow alterations into the inner ear's vestibule. Patients with mild elevations will be presented to the clinic, similar to migraines with or without the presence of pulsatile tinnitus. Treatment requires lowering intracranial pressure and managing migraine symptoms.

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.

Peripapillary Vessel Density Measured by Optical Coherence Tomography Angiography in Idiopathic Intracranial Hypertension

BACKGROUND

Although alterations in the peripapillary retinal nerve fiber layer (RNFL) in patients with idiopathic intracranial hypertension (IIH) have been characterized using optical coherence tomography (OCT), there are little data regarding the peripapillary vasculature in this patient population. Our aim was to evaluate findings of OCT angiography (OCT-A) in the peripapillary region in addition to the RNFL measurements on OCT in patients with IIH.

METHODS

Thirty-eight eyes of 19 patients with IIH and 42 eyes of 21 healthy controls were enrolled in our study. Papilledema was graded according to the Frisen scale. Peripapillary RNFL and vessel density were evaluated with OCT and OCT-A, respectively.

RESULTS

RNFL thickness was found to be increased with OCT, but this was statistically significant only in the inferior location in IIH patients when compared with the control group. There was a significant decrease in mean peripapillary vessel density measured with OCT-A in IIH patients with papilledema when compared with the control group (P < 0.05).

CONCLUSIONS

In patients with IIH, there was a decrease in peripapillary vessel density measured by OCT-A, and this decrease may be a consequence of the swelling of axons in the peripapillary retina due to papilledema. However, autoregulatory vascular mechanisms may also play a role in decreased peripapillary vessel density.

Flow velocity and pulsatility of the ocular circulation in chronic intracranial hypertension

OBJECTIVES

The aim of this study is to examine the relationship of ocular blood flow velocities and pulsatility to intracranial pressure (ICP).

METHODS

We measured arterial and venous flow velocities using color Doppler imaging (CDI) and calculated resistance indices for the central retinal (CRA) and the ophthalmic (OA) arteries from 16 patients (32 eyes) with chronic intracranial hypertension (ICH) and varying degrees of ICP and papilledema. The results were compared with normal data from 16 age-matched, healthy subjects.

RESULTS

Arterial flow velocities were significantly decreased for the aggregate subject group compared with controls. A corresponding rise in arterial resistance with increasing ICP in the mild-moderate range was noted. Unexpectedly, with more severe elevations of ICP these trends reversed.

CONCLUSIONS

In mild-moderate increased cerebrospinal fluid (CSF) pressure, a reduction of flow velocities may result because of increased vascular resistance. Paradoxically, in more severe chronic ICH, we hypothesize that local autoregulatory vascular changes and/or diversion of cerebral blood flow into the ophthalmic circulation may normalize these parameters. This phenomenon may partially underlie the relative sparing of visual function early in the course of pseudotumor cerebri (PTC), regardless of actual ICP levels.

Benign intracranial hypertension: correlation of cerebral blood flow with disease severity

Benign intracranial hypertension (BIH) is characterized by symptoms and signs of raised intracranial pressure in the absence of an intracranial mass lesion, infection or hydrocephalus. The purpose of this study was to evaluate the effect of disease severity on cerebral blood flow in patients with BIH on acetazolamide therapy.

METHODS

11 patients (nine females, two males; mean age 30.5 years; range 22-29 years) with BIH were studied. All patients underwent CT and MRI scanning which were normal. The CSF pressure of all patients was above 200 mm H2O. All patients were under treatment with acetazolamide (1 g/day). Disease severity was determined by visual field examination and by clinical symptoms. Five patients were categorized into mild to moderate BIH (group I) and six patients had severe BIH (group II). All patients underwent perfusion brain SPECT with 740 MBq of Tc-99m-HMPAO.

RESULTS

Brain perfusion abnormalities were observed in six of the 11 patients. One out of five patients in group I (20%) and five out of six patients (83%) in group II, had abnormal SPECT findings (P<0.04). In four patients of group II the left parietal lobe was involved and another patient had a right occipital abnormality. The single patient from group I with SPECT abnormalities demonstrated focal decreased perfusion in the left temporal area and decreased perfusion in the left caudate nucleus.

CONCLUSION

Patients with severe degree of BIH have a higher incidence of cerebral perfusion abnormalities. This group may have an increased risk of cerebrovascular complications. The continuous administration of acetazolamide which affects the vascular autoreactivity may contribute to the regional hypoperfusion. Further studies are recommended to evaluate the natural course of disease versus iatrogenic treatment effects.