Titanium mesh-assisted dural tenting for an expansile suboccipital cranioplasty in the treatment of Chiari 1 malformation

Establishing proof of concept for sonolucent cranioplasty and point of care ultrasound imaging after posterior fossa decompression for Chiari malformation

BACKGROUND

Evaluation after posterior fossa decompression for Chiari malformation can require repeated imaging, particularly with persistent symptoms. Typically, CT or MRI is used. However, CT carries radiation risk and MRI is costly. Ultrasound is an inexpensive, radiation-free, point-of-care modality that has, thus far, been limited by intact skull and traditional cranioplasty materials. Ultrasound also allows for imaging in different head positions and body postures, which may lend insight into cause for persistent symptoms despite adequate decompression on traditional neutral static CT or MRI. We evaluate safety and feasibility of ultrasound as a post-operative imaging modality in patients reconstructed with sonolucent cranioplasty during posterior fossa decompression for Chiari malformation.

METHODS

Outcomes were analyzed for 26 consecutive patients treated with a Chiari-specific sonolucent cranioplasty. This included infection, need for revision, CSF leak, and pseudomeningocele. Ultrasound was performed point-of-care in the outpatient clinic by the neurosurgery team to assess feasibility.

RESULTS

In eight months mean follow up, there were no surgical site infections or revisions with this novel sonolucent cranioplasty. Posterior fossa anatomy was discernable via transcutaneous ultrasound obtained point-of-care in the clinic setting at follow up visits.

CONCLUSION

We demonstrate proof of concept for ultrasound as a post-operative imaging modality after posterior fossa decompression for Chiari malformation. With further investigation, ultrasound may prove to serve as an alternative to CT and MRI in this patient population, or as an adjunct to provide positional and dynamic information. Use of sonolucent cranioplasty is safe. This technique deserves further study.

Interlayer dural split technique for Chiari I malformation treatment in adult-Technical note

OBJECTIVE

To present an alternative surgical technique in treating cases of Chiari I Malformation with mild-to-moderate syringomyelia after decompressive suboccipital craniectomy: incising only the outer layer of the dura mater, then dissecting it from the inner layer without opening the latter.

PATIENTS AND METHODS

We utilized this technique in a short series of three cases who were admitted to our department for mild symptoms such as intermittent headache and dissociated sensory loss in the upper limbs, caused by a Chiari Malformation Type I. The patients were placed in the sitting position. We performed a reduced median suboccipital craniectomy and resection of the posterior arch of C1 adapted to the level of tonsil descent, from a limited superior half to complete resection. Afterward, we incised the outer dural layer, while sparing the inner one. Using a fine dissector, we then split apart the outer and inner layers to the margin of the craniectomy. Through the transparency of the inner layer and the arachnoid, the cerebellum and the medulla were visible and pulsating. An autologous fascia duraplasty was then performed.

RESULTS

The postoperative course was favorable in all cases, the patients being discharged without any deficits and with complete symptom resolution. Follow-up at 3, 6, and 12 months after surgery revealed a significant reduction in brainstem compression and syringomyelia.

CONCLUSIONS

Interlayer dural split technique can be used effectively in treating symptomatic cases of type I Chiari malformation in adults, with mild-to-moderate syringomyelia. It is less invasive than opening the dura and possibly more effective than decompressive craniectomy and C1 laminectomy alone. This technique must be validated in a larger case-control series.

A titanium implant for Chiari malformation Type 1 surgery

Background

Concepts of Chiari malformation Type 1 (CM1) surgery in the present time significantly different. The most common complications are pseudomeningocele (12%) and postoperative CSF leak (5%). The development of pseudomeningocele may be associated with inappropriate restoration of bone and muscles relations.

Methods

The pilot study involved 11 patients aged 24-64 years with a diagnosis of CM1 who had indications for surgical treatment. Special titanium implant enabling fixation of the occipital and cervical muscles at the projections of their normal attachments was developed, it was placed to occipital bone on the final stages of surgical intervention. Surgical technique promoted tightened wound closure neutralizing formation of "dead space" at the place of occipital craniectomy and between muscle layers. The implant was produced by direct metal laser sintering method for each patient individually.

Results

There were no complications during the hospitalization and follow-up period. Postoperative MRI demonstrated adequate formation of the cisterna magna and the absence of pseudomeningocele. During follow-up period there were no signs of pseudomeningocele, CSF leak, surgical scar complications, implant-associated infections, and other complications.

Conclusion

In the study group, no pseudomeningocele cases as long as any other complications associated with surgery had been revealed. The efficacy of the proposed surgical technique using the developed implant should be evaluated in clinical trials with larger patient samples. To simplify preoperative planning and manufacturing of the implant for each patient individually, a set of implants with different specified sizes was developed.

Management of hydrocephalus and subdural hygromas in pediatric patients after decompression of Chiari malformation type I: case series and review of the literature

OBJECTIVE

Hydrocephalus associated with subdural hygromas is a rare complication after decompression of Chiari malformation type I (CM-I). There is no consensus for management of this complication. The authors present a series of 5 pediatric patients who underwent CM-I decompression with placement of a dural graft complicated by posterior fossa hygromas and hydrocephalus that were successfully managed nonoperatively.

METHODS

A retrospective review over the last 5 years of patients who presented with hydrocephalus and subdural hygromas following foramen magnum decompression with placement of a dural graft for CM-I was conducted at 2 pediatric institutions. Their preoperative presentation, perioperative hospital course, and postoperative re-presentation are discussed with attention to their treatment regimen and ultimate outcome. In addition to reporting these cases, the authors discuss all similar cases found in their literature review.

RESULTS

Over the last 5 years, the authors have encountered 194 pediatric cases of CM-I decompression with duraplasty equally distributed at the 2 institutions. Of those cases, 5 pediatric patients with a delayed postoperative complication involving hydrocephalus and subdural hygromas were identified. The 5 patients were managed nonoperatively with acetazolamide and high-dose dexamethasone; dosages of both drugs were adjusted to the age and weight of each patient. All patients were symptom free at follow-up and exhibited resolution of their pathology on imaging. Thirteen similar pediatric cases and 17 adult cases were identified in the literature review. Most reported cases were treated with CSF diversion or reoperation. There were a total of 4 cases previously reported with successful nonoperative management. Of these cases, only 1 case was reported in the pediatric population.

CONCLUSIONS

De novo hydrocephalus, in association with subdural hygromas following CM-I decompression, is rare. This presentation suggests that these complications after posterior fossa decompression with duraplasty can be treated with nonoperative medical management, therefore obviating the need for CSF diversion or reoperation.

Symptomatic ptosis cerebelli after suboccipital craniectomy in a patient with severe brain trauma

PRIMARY OBJECTIVE

To report the first case of symptomatic cerebellar ptosis after a large suboccipital craniectomy in a patient with severe brain trauma and a review of the literature.

PATIENT AND METHODS

A 36-year-old man suffered severe traumatic brain injury after a four-metre fall. He underwent a large suboccipital craniectomy because his computed tomography scan revealed a posterior fossa subdural haematoma and cerebellar swelling. Four weeks after admission, he developed communicating hydrocephalus, and a ventriculoperitoneal shunt was placed. Although he experienced good recovery, seven months after the trauma he complained of cephalea, dizziness, recurrent vomiting and diplopia. Magnetic resonance imaging (MRI) showed descent of the cerebellum through a wide bone defect.

RESULTS

We performed a posterior fossa cranioplasty after other causes of delayed worsening were ruled out, such as shunt malfunction, overdrainage and ischaemic lesions. The patient improved, and a post-operative MRI confirmed the upward migration of the cerebellum.

CONCLUSIONS

Cerebellar ptosis must be considered in cases of delayed symptoms after large suboccipital craniectomy regardless of pathology. Posterior fossa cranioplasty to provide structural support to slumped cerebellum can improve or resolve symptoms.

"Stealth cranioplasty:" A novel endeavor for symptomatic adult Chiari I patients with syringomyelia: Technical note, appraisal, and philosophical considerations

Aim and Objective:

In this article, we describe a novel technique of reconstruction of posterior fossa by cranioplasty with use of preshaped titanium mesh following posterior fossa decompression (PFD) for Chiari malformation type I (CMI) with syringomyelia (SM) in symptomatic adults.

Materials and Methods:

Eleven patients underwent limited PFD and expansive cranioplasty with preshaped titanium mesh, what we term as “Stealth Cranioplasty” (SCP), following arachnoid preserving duraplasty (APD) and hexagonal tenting of the duraplasty with the cranioplasty (HTDC) for the management of symptomatic adult CMI with SM. All these patients had syringes extending from 3 to >10 vertebral levels.

Results:

Seven male and four female symptomatic CMI adult patients, between age ranges of 22 and 44 years (mean 29.45 years), presented with different neurological symptoms related to CMI and SM for 6–84 months (mean 37.09 months). All the patients underwent PFD, APD followed by SCP and HTDC and were followed up for 7–54 months (mean 35.90 months). Of 11 patients, 8 patients improved according to the Chicago Chiari Outcome Scale (CCOS) with score of 13–15 while 3 patients remained unchanged with CCOS of 12, and there was no worsening. There was no complication related to Chiari surgery in any of the patients. All the patients had good reestablishment of cisterna magna. Two patients had marked reduction of syrinx while eight patients had moderate-to-mild reduction and one patient had no change of syrinx. None of the patients needed redo surgery.

Conclusion:

SCP is an effective, fruitful, and cost-effective technique for the management of symptomatic adult CMI with SM. This technique has the advantages of preventing complications and recurrences in addition to the improvement of symptoms by addressing the basic pathology.