Giant Lumbar Pseudomeningocele Compression Mimicking Stroke and Seizure

PRACTICAL IMPLICATIONS

Acute awareness impairment, confusion, or other neurologic symptoms occurring in supine position should raise the possibility of transient intracranial hypertension, notably through the compression of a possible pseudomeningocele.

Pseudomeningoceles are extradural accumulations of CSF after a dural defect. We report the case of a giant postoperative lumbar pseudomeningocele, whose compression induced increased intracranial pressure and syncope. The clinical presentation of impaired consciousness and paroxystic movements of all limbs mimicked stroke and seizure.

Case

An 81-year-old woman with type II diabetes, hypertension, and previous lumbar surgeries presented with an abrupt episode of aphasia and agitation. Her clinical presentation was suggestive of stroke, and intravenous thrombolysis was performed. Confusion and agitation persisted, leading to intubation. The MRI revealed no ischemic lesions, so the diagnosis of a transient ischemic episode was retained.

Similar recurring episodes with brief bilateral clonic jerks or nonrhythmic movements led to 2 further admissions to the intensive care unit. An epileptic origin was considered because no new MRI lesion was found. The EEG showed a left frontal slow dysfunction with no epileptiform activity. Lamotrigine and clonazepam were initiated and subsequently replaced by levetiracetam, which was better tolerated.

Over the following 2 years, the initially rare episodes gradually increased in frequency, leading to the current admission. Progressive escalation of antiepileptic drug treatment proved unsuccessful, with daily paroxystic episodes and increasing confusion requiring physical bed restraints. A new EEG showed a mild to moderate encephalopathy with a toxic-metabolic component. A lumbar puncture revealed only unspecific giant cells and elevated protein levels, which were attributed to previous back surgery, but no tumoral markers. An underlying neurodegenerative etiology was also proposed, given the persistent confusion.

The nursing team reported that symptoms consistently occurred when the patient was in the supine position and disappeared in lateral decubitus or standing position. It raised the suspicion that they could be related to her pseudomeningocele. Her surgical history included a left L5-S1 microdiscectomy in 1983, a L2-S1 laminectomy for lumbar spinal stenosis in 2010, a right L5-S1 decompression in 2015, and a right L4-L5-S1 nerve root decompression in 2016. This last procedure, 2 months before the first episode, was complicated by a dural tear leading to a giant pseudomeningocele (figure 1).

Figure 1. MRI of the Pseudomeningocele.

MRI showing the giant pseudomeningocele measuring 17 cm in craniocaudal length and 9 cm in anteroposterior width shown in sagittal T2 (A) and in volume rendering (432 mL, C) caused by a dural tear (red arrow, axial T2, B) during a neurosurgical procedure.

Dizziness and loss of contact followed by confused speech and nonrhythmic jerking movements of all limbs were reproduced by manual compression of the pseudomeningocele or in supine position. On the video-EEG, the clinical episodes provoked by compression showed the typical pattern of syncope caused by cerebral hypoperfusion, with diffuse slowing followed by EEG flattening without cardiac arrhythmia (figure 2). A transcranial Doppler during the pseudomeningocele compression showed a diminution of cerebral blood flow velocities with the total disappearance of the diastolic signal from both middle cerebral arteries (figure 2).

Figure 2. Transcranial Doppler and EEG Recordings of the Paroxystic Episodes.

Transcranial Doppler ultrasound of the left middle cerebral artery before, during, and after manual compression of the pseudomeningocele showing a decrease of intracerebral blood velocities with total disappearance of the diastolic signal during the compression (between the red and green arrows) (A). EEG recording before, during, and after clinical episodes provoked by lumbar pseudomeningocele compression (between the red and green arrows) showing a pattern of diffuse slowing, followed by attenuation typical of brain hypoperfusion (syncope) (B).

The progressive weaning out of all antiepileptic medication was paralleled by an important cognitive improvement. An open surgical procedure for extirpation of the pseudomeningocele and dural closure was performed. There was no postoperative recurrence of the episodes at the 1-year follow-up.

Discussion

A pseudomeningocele is an extradural accumulation of CSF following a dural tear. Conservative management options include bedrest, puncture, or compressive dressing. Although small pseudomeningocele usually resolve themselves, large (>5 cm) or giant ones (>8 cm) may need surgical repair.^1,2

This pseudomeningocele was particularly large measuring 17 cm in length with a volume of 432 mL and immense in relation to the whole CSF (70–160 mL). Rarely have larger pseudomeningocele (20 cm) been described.³

These lesions are usually asymptomatic. However, they may cause back pain, radiculopathy, headache, nausea, or vomiting. In our case, the increased pressure on the pseudomeningocele was transmitted to the intracranial space through a dural opening located at the posterior right L4 level. This led to a corresponding increase of intracranial pressure, a reduced blood perfusion, and a convulsive syncope with no epileptic origin as shown in our electrophysiologic studies. Few cases of pseudomeningocele compression causing increased intracranial pressure and presenting with loss of consciousness have been described in the literature.^4-7 One other case of convulsive syncope on pseudomeningocele compression without sequelae has been documented.⁴ As in our case, the symptoms were correlated to simultaneous diffuse flattening of the EEG; however, the reported simultaneous cardiac arrhythmia with ectopic ventricular beats⁴ was not observed in our case. In other cases, the effects were irreversible with prolonged compression causing retinal hemorrhage in 1 case⁵ and diffuse cerebral ischemic lesions in another.⁶ In our case, 2 small retinal hemorrhages in the context of hypertensive retinopathy could not be formally attributed to intracranial hypertension.

The diagnostic delay (3 years) and the high number of events (>100) before surgical correction reminds us of the importance of considering a large differential diagnosis of paroxysmal “seizure-like” events. When they occur in supine position, transient intracranial hypertension should be considered. In addition, it highlights the necessary precautions required in dealing with pseudomeningocele to prevent consequences of brain hypoperfusion.

Appendix. Authors

Study Funding

S. Vulliemoz is supported by Swiss National Foundation grants (Nos. 170873 and 192749).

Disclosure

The authors report no disclosure relevant to the manuscript. Full disclosure form information provided by the authors is available with the full text of this article at Neurology.org/cp.