Dear Butchart,

It is the best way to put tissel after closing the dura. The important point is to stop bleeding from the epidural space. If  you provide a bloodless clean area, tissel will adhere well over the dura. It is not necessary to fill any tissue. It is enough to close outer wound.

Dr Fahir Ozer

Thank you Dr Ozer

The pseudomeningocel developed and filled the cavity over the back of the spinal canal resulting from the laminectomy, following surgery to remove an intradural tumour as described in the previous questions you responded to.  

The pseudomeningocel first appeared on monitoring MRI images, 6 months after the tumour had been removed. Though the patient was not aware that the pseudomeningocel had appeared on the MRI images, additional symptoms were reported a few weeks after those monitoring MRI images became available. The reported symptoms continued and increased until investigative and corrective surgery located and repaired the dural defect three years later.  During those three years the patient was admitted as a suspect stroke on two occasions.  The symptoms and facial droop resolved while in hospital and CT and MRI scans of the head and brain found no problems.  

As you noted in your previous response, the difference between the radiologists reports on the first monitoring MRI and the second monitoring MRI scan 6 months later, indicated that the pseudomeningocel was still expanding.  The radiologists report on the second monitoring MRI scan indicated that the pseudomeningocel was still expanding as the post surgical changes in the posterior vertebral soft tissue became less prominent. The pseudomeningocel appeared on monitoring MRI images every 6 months over the three years, until successful investigative and corrective surgery was completed.  Monitoring MRI scans 12 and 24 moths later confirmed that the corrective surgery had been successful.   

Investigative and corrective surgery, three years after the tumour was removed, located the defect in the dura and the one-way valve system you described.  The defect found was considerably larger than had been expected, presumably due to the flow of CSF under pressure through the defect and into the pseudomeningocele through the one-way valve. See the attached photograph.  

Would the three years during which the pseudomeningocel had been filling the cavity and repeatedly been re-pressurised by the flow of CSF from within the dura make any difference as to how you would deal with the cavity following repair of the dural defect? 

I agree with Dr. Ozer. We usually use a gelatin sponge strip (Gelaspon) placing it over dura which provides local hemostasis. This is a very important issue. Afterwards we suture the paravertebral muscles in an inverted manner to reduce the empty space. In some cases we use a thin suction drainage for 48 hours (if no CSF leakage is present !). We find it very useful to ensure bloodless wound and less late adhesions.

Thank You Dr Tanchev

Would the three years during which the pseudomeningocel had been filling the cavity and repeatedly been re-pressurised by the flow of CSF from within the dura make any difference as to how you would deal with the cavity following repair of the dural defect?

In such case the cavity is difficult to fill completely. Anyway, one could try a sort of capitonage with inversion of paravertebral muscles.

Would that be some form of foam matrix?  Shaped and secured to fill the cavity, maintain the necessary epidural space and injected with autolgous fluids?  The objective being to provide structural support for the formation of a clot which would be absorbed and form part of the surrounding tissue.  So forming suitable filler and obliterating the cavity. 

I agree with Dr Duntsch. It is very unusual to try to fill up a post laminectomy defect with any material after completing dural closure. I think the concern is whether the dead space leads to development of a pseudomeningocoele in the absence of posterior support to the repaired dura. In my opinion a proper surgical closure of the dead space by approximation of the para spinal muscles in layers usually suffices in most patients. I suppose a pseudomeningocoele would create its own space  gradually and this would occur independently of whether the extradural cavity was obliterated well or not. I think a good Dural closure with special care to the ends of the durotomy would be crucial to preventing the development of a pseudomeningocoele. I usually close spinal dura with 5 O prolene continuous mattress sutures starting at both ends of the durotomy and tying the two sutures in the middle. In my opinion it is advantageous for closure of the ends of the durotomy which is the usual position of a CSF leak. Using duraseal over the suture line may also help. I usually keep a wound drain if needed in between the muscles rather than extradurally as I feel the negative pressure even with gravity drainage may be enough to create a CSF leak. It may be useful to leave some blood clot over the repaired dura to prevent a leak rather than trying to have a bone dry field. This will fill up the remaining dead space as long as there is no active bleeding and the clot is not causing any pressure. It is also important to remember that the immediate post operative dead space is more as compared to later as loss of CSF during the operation leads to a lax Dural tube which gradually fills up later to decrease the dead space.

Thank you Christopher for your response.

Thank you Rohail for a very comprehensive response.  Do you have any thoughts on the suturing shown in the photograph above and attached.  Those are the original sutures used to close the dura after removal of the tumour three years before the dural defect was located and photographed.  The cavity in which the pseudomeningocele had formed and remained for three years, was obliterated by adding a matrix injected with autologous fluids.  A lumbar drain was left in place for a week to allow the complex wound to heal with the CSF, maintained at a lower than normal pressure.  See attached images of the pseudomeningocel covering the combined length of the T9 & T10 vertebrae .  The pseudomeningocele having been repeatedly pressurised with CSF via the permanently open and expanding defect with a one-way valve and permanent connection. 

Dear Butchart,

Normally it is not need to fill the cavity with any tissue or any material after closing the dura. If pseudomeningocell develops after surgery,  it is not necessary to repair it immediately. Emergency operation should be performed only CSF leakage from the wound. We know that dural defect becomes a small hole due to repair process of organism. When we open the cavity after a while, we see a pseudo membrane  of the cavity and a very small dural defect. It is easy to close this small defect. If the cavity re-developes ,you should check CSF pressure. If it is normal this means that your repair is insufficient. If it is high CSF presure than normal, this situation shows the patient has high CSF pressure because of any reason.  In this case you should put a syringo peritoneal shunt to reduce the CSF pressure  and repair the cavity at the same seans. In such rare cases the main pathology "increased intracranial pressure" is overlooked easily. The reason of high intracranial pressure can be detect after repairing process.

Ali Fahir Ozer 

Thank you Ali Fahir Ozer for another comprehensive explanation.  Investigative and corrective surgery was done three years after the intradural tumour was removed.  The defect in the dura just above the lower suture which was used to close the wound and the pseudo membrane and the pseudo membrane can be seen in the attached image. 

Dear All

Given the excellent answers provided above I would assume you would not agree with the following statements.  These statements were made in a letter by the neurosurgeon who removed the intradural schwanoma tumour in 2008, in response to a neurologist who requested an explanation as to why the neurosurgeon strongly advised against surgery to investigate and correct the pseudomeningocele in 2011.  

The reason that the meningocele is present is because of the loss of the bone and muscle over the back of the spinal canal at that point in the process of performing surgery to remove the schwannoma.

There is no tissue nearby to fill in this space, and to do this would require an extensive plastic mobilisation of muscle with transportation into the space.

This would not, to my view, make any sense whatsoever, and would put the patient at risk of surgery for no benefit.

Serious surgery indeed.

The very successful investigative and corrective surgery was completed eight months later.  The neurosurgeon who performed the investigative and corrective surgery did not accept that any form of plastic surgery was required.  His detailed plan for the investigative and corrective surgery was as follows:

• Reopening of the cyst, exposure of the dural sac and the leak,
• covering of the leak with autolugous tissue plus glue,
• reduction of the cyst space with resection of the surface to create sticky surfaces,
• lumbar drain for one week to allow the complex wound to heal and seal without the pressure of CSF.

The above plan seems to fit the thoughts of all who have provided answer to my question.

The debilitating symptoms which the patient had suffered started a few weeks after the pseudomeningocel first appeared on the monitoring MRI scan, done 6 months after the schwannoma tumour was excised.  

Those symptoms continued and increased over the following three years and resulted in two emergency admissions as a suspect stroke which could not be explained by CT and MRI scans of the head and brain.  Over those three years the only form of tests done apart form 6 monthly MRI scans were the basic neurological push pull on all four limbs, reflex tests and skin pricking on leg and foot.  The two strokes resulted in left side facial droop and a slight slurring of speech, occurred the morning after the patient had attempted circuit training under the supervision of a physiotherapist.  The exercise to regain fitness involved using a walking machine cross trainer and stationary bike at the lowest possible setting following which the patient then walked home.  On both occasions the facial weakness and the speech defect resolved following several hours bed rest.  

The question asked by the neurologist resulted following referral to that neurologist after the two suspect strokes.  But again only the basic neurological tests were done, the only addition being the use of a tuning fork.  The neurologist advised the patient that given the intradural tumour his recovery had been relatively good and any further surgery would involve potential risks that the patient should carefully consider the risks involved.  However as for the neurosurgeon the neurologist was unable to define those risks but agreed to ask the neurosurgeon to do so.

Since the very successful investigative surgery the patient recovered well and in June this year climbed his first 3000 ft mountain since his CNS problems first became apparent while on a week long hill walking and climbing holiday.  The CNS symptoms only occurred during his night time sleep period during the second half of that holiday, and he had continued to climb during the day.  Only on returning home did the CNS symptoms and continue over 24 hours and become rapidly more painful.  

Very similar to the problems resulting from the pseudomeningocele the diagnosis for four months was sciatica.  For which the policy was no form of imaging, tests or treatment other than pain killers (Diclofenac & Tramodol) and an assessment by physiotherapists who diagnosed a stiff lower back.  As with the pseudomeningocel the only form of tests was the basic neurological.  However when the patient persuaded a GP to request an MRI SPINE the neurosurgeon without meeting the patient authorised only an MRI of the Lumbar and Sacral Spine only. The neurosurgeon having downgraded the GPs request for an urgent referral two months earlier.  

Fortunately the radiographer used the full travel of the scanner table and luckily the tumour the radiologists described as flattening the spinal cord, pushing the spinal cord and the T9 nerve root to the rear and side of the spinal cord was found within the top 1/2" of the MRI images.  Luckily as obviously had the tumour been above T8 it would not have been found by that limited MRI scan.

Any comments would be appreciated.  MRI image showing schwannoma tumour.

after a laminectomy an space free of bone remains over the dura. It is not customary to cover or replace the bone unless a laminoplasty has prevously been planed,in such cases the laminae are replaced and fixed.I agree that in a pseudomeningocele like the present case ,finding and closing the dural leak is the best solution

Thank you Jorge.

Your contribution is much appreciated.

It has been a while since the last response to my question, but for some reason searches of my details in this and other media accounts continue.  I thought it time to show why I asked the question.  I have therefore provided a copy of the Consultant Neurosurgeons response to his Colleague a Consultant Neurologist who requested details of the risks associated with Operational Procedures on the Pseudomeningocele.  As you will see the answer involved extensive plastic surgery to fill the cavity over the back of the spinal canal created during the laminectomy as there was no tissue nearby to do so.

In the light of the earlier responses above I will await any further thoughts on the content of the following letter.