In March 2019, the patient had a suboccipital craniectomy with C1-C2 laminectomy for decompression of a Chiari I malformation. The surgeon documented that after the craniectomy, he saw good pulsatility. The patient's symptoms improved at first. 6 months to a year later, the patient began to have neurological symptoms including headaches and severe confusion. She was assessed at Mayo but the neurosurgeon there did not think the Chiari was the problem. Eventually, in August 2021, she was seen at a Chiari specialty clinic in Kentucky, where the neurosurgeon told her that she had blocked CSF flow in one location from the Chiari, and that the first surgeon in 2019 should have done a duraplasty with the craniectomy, to get greater decompression. He took her in for a revision with duraplasty, and in the aftermath she had a pseudomeningocele, requiring rehospitalization. The patient claims she now has substantial cognitive issues, which she attributes to increased CSF pressure during the time between the two decompressions. She does not appear to have been diagnosed with hydrocephalus at any point. She also did not have syringomyelia at any point, in case that is relevant to the duraplasty issue.
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Do you believe there might have been medical error?
I regularly treat this condition and perform this surgery often. Duroplasty is often done, but it is not required step in this surgery. It requires careful review of the patient’s symptoms, imaging, and anatomy.
Do you believe there might have been causation (i.e. the medical error resulted in an injury)?
Please see above response. Most of the time, duraplasty should be performed during a routine Chiari decompression.
What makes you a good expert for this case?
I am board certified with over 15 years of academic neurosurgery experience. I have extensive experience in case review. I regularly do cranial surgery including this one.
How often do you encounter cases similar to this one in your practice?
I get referrals for Chiari malformation want to two times per month. About 50% of these require operative intervention.
Do you believe there might have been medical error?
There is a body of literature supporting Chiari decompression without duraplasty. The risk of recurrence is higher, but the morbidity is lower. Duraplasty involves additional risk as was evident by her subsequent pseudomeningocele which required hospitalization. (Ref 1) The questions to address would if the overall care was substandard. How was the diagnosis made? Was CSF flow study (CINE) MRI performed before and after surgery? Why was C2 laminectomy needed? Generally C1 is sufficient. And she is older than most Chairi patient's so why was she identified so late? Her symptoms of confusion and cognitive decline do not make sense in the context of Chiari malformation. The pressure between surgeries is irrelevant since this condition is congenital and she would have had pressure from the time of her skeletal maturation (late teens) until her age of diagnosis 43. She improved post-operatively so the pressure was less, even if not perfect. The literature shows Chairi patients often have cognitive dysfunction and or impaired visuospatial skilled, and sometimes improve with surgery. Ref. 2 Most importantly the cerebellum is a sort of "lizard brain" it does not have any direct role in memory or higher cognitive functions. A few extra months of 'pressure' on the cerebellum or spinal cord could not be causally related to memory loss of confusion. 1. Mutchnick IS, Janjua RM, Moeller K, Moriarty TM. Decompression of Chiari malformation with and without duraplasty: morbidity versus recurrence. J Neurosurg Pediatr. 2010;5(5):474-478. doi:10.3171/2010.1.PEDS09218 2. Allen PA, Houston JR, Pollock JW, et al. Task-specific and general cognitive effects in Chiari malformation type I. PLoS One. 2014;9(4):e94844. Published 2014 Apr 15. doi:10.1371/journal.pone.0094844
Do you believe there might have been causation (i.e. the medical error resulted in an injury)?
Causation in relation to the patient's reported decline would be very hard to demonstrate. The patient was diagnosed with Chairi malformation which is congenital and would have had pressure on the brain and spinal cord all her life. How would some additional residual pressure for 6 months result in new incapacitation? The "incomplete" decompression is not a medical error, just a variation on a technique, which is acceptable if the work-up was detailed and the plan was justified. The causation is also confounded by the second surgery. Pseudomeningocele is a serious complication with entrapped fluid causing worse compression on the spinal cord and cerebellum than the Chari itself. It also presents a high risk of infection/meningitis. If there is any causation the second surgery was likely the culprit and I agree with the Mayo assessment that her memory issues were unrelated.
What makes you a good expert for this case?
I trained with the top experts in this surgery (Dr Edward Oldfield, former NIH Director of Neurosurgery). I have participated in detailed studies of the technique using intraoperative MRI to check the degree of decompression after bone removal, and after duraplasty. I perform a reasonable volume of these cases with minimal complications (close to 0), and I revise Chiairi surgeries performed by other surgeons so I have lots of experience with the complications including pseudomeningocele.
How often do you encounter cases similar to this one in your practice?
I perform 2-3 per month including revisions from other surgeons. I have encountered several hundred during my career.
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