hydrocephalus_after_posterior_fossa_decompression_for_chiari_type_1_deformity

Posterior fossa decompression surgeries for Chiari malformations are susceptible to postoperative complications such as pseudomeningocele, external cerebrospinal fluid (CSF) leak, and meningitis. Various dural substitutes have been used to improve surgical outcomes.

Cerebrospinal fluid disturbance (CSFD) is a well-known complication after occipitocervical decompression (OCD) in patients with Chiari malformation type I (CMI). There is scarce data focusing on preoperative patients' factors predisposing to development of CSF disturbance. The aim of this study is to evaluate a prognostic value of some patients' factors in the prediction of CSFD after OCD in CMI patients.

A 10-year (2003-2013) retrospective study of all OCD in patients with CMI performed at Sahlgrenska IC, Sahlgrenska University Hospital, Sweden. A total of 52 consecutive patients were obtained from the operation database and we excluded one patient who was previously diagnosed with normal-pressure hydrocephalus. Data regarding preoperative age, body mass index, gender, degree of tonsillar herniation and syrinx were registered. Development of CSFD after OCD was noted.

Of the 51 patients reviewed, six had CSFD after OCD and were managed using a form of CSF diversion procedure. All of the patients who developed CSFD were females. They had a mean body mass index of 32.3 compared to a mean of 24.3 in patients without CSFD (pā€‰=ā€‰0.0011). There was no difference between the two groups with regard to the other examined patient factors.

CSF diversion was needed in six consecutive adult Chiari malformation type I patients who underwent occipitocervical decompression. All patients with postoperative CSFD were female and their mean BMI was significantly higher than patients without this complication 1).


Although patients sometimes demonstrate evidence of hydrocephalus during their initial presentation for CM-I, a subset of patients appear to develop hydrocephalus only after posterior fossa decompression. These patients may present with evidence of raised intracranial pressure, ventricular dilation on imaging, or persistent cerebrospinal fluid leakage postoperatively. To date, there are no reports in the literature investigating what factors are associated with the need for CSF diversion after PFD is performed to treat CM-I.

Guan et al. performed a retrospective clinical chart review of all patients who underwent PFD surgery and duraplasty for CM-I at the Primary Children's Hospital in Utah from June 1, 2005, through May 31, 2015. Patients were dichotomized based on the need for long-term CSF diversion after PFD. Analysis included both univariate and multivariable logistic regression analyses.

The authors identified 297 decompressive surgeries over the period of the study, 22 of which required long-term postoperative CSF diversion. On multivariable analysis, age < 6 years old (OR 3.342, 95% CI 1.282-8.713), higher intraoperative blood loss (OR 1.003, 95% CI 1.001-1.006), and the presence of a fourth ventricular web (OR 3.752, 95% CI 1.306-10.783) were significantly associated with the need for long-term CSF diversion after decompressive surgery.

Younger patients, those with extensive intraoperative blood loss, and those found during surgery to have a fourth ventricular web were at higher risk for the development of CRH. Clinicians should be alert to evidence of CRH in this patient population after PFD surgery. 2) 3).

Elton et al. present three patients who developed infratentorial supracerebellar hygromas causing acute hydrocephalus after posterior cranial fossa decompression 4).

A 34-year-old woman presented with strain-related suboccipital headache and myelopathy for 6 months. Imaging revealed tonsillar herniation up to C2 level and cervical syringomyelia. A standard FMD, C1 posterior arch removal, and tonsillar reduction was performed. After an initial uneventful postoperative course, she had 2 readmissions with headache, vomiting, and ataxia. Imaging showed a tense pseudomeningocele and concomitant supratentorial and infratentorial (initially right-sided, followed by left-sided) SDHs with ventriculomegaly. She was conservatively managed with antiedema measures and had excellent relief of symptoms. For the literature review, only cases with concomitant supratentorial and infratentorial SDHs with hydrocephalus were searched online and analyzed.

Including this, 10 cases have been reported. Mean age was 25.3 years. The male-to-female ratio was 1:2.3. Symptoms appeared an average of 12.6 days postoperatively. Treatment was with conservative management in 3 cases, and 3 cases required permanent cerebrospinal fluid diversions. Mean follow-up duration was 9.4 months (range, 1-27 months).

Coexistent supratentorial and infratentorial SDHs with hydrocephalus after Chiari decompression is a very rare occurrence. Treatment needs to be individualized based on the predominant symptomatic lesion, and surgical options need to be judiciously considered. Good prognosis is the rule in most cases 5).


A 2-year-old girl with the Chiari 1 malformation underwent FMD, including suboccipital craniotomy, C1 laminectomy and durotomy without opening the arachnoid.

After initial postoperative improvement, the patient deteriorated, developing subdural hygromas and hydrocephalus. These were treated successfully with observation and acetazolamide.

Subdural hygromas may complicate FMD. A slit valve opening in the arachnoid might be part of the pathophysiology. While surgical intervention may be necessary in some circumstances, non-operative measures may be effective as well 6).


1)
Almotairi FS, Tisell M. Cerebrospinal fluid disturbance in overweight women after occipitocervical decompression in Chiari malformation type I. Acta Neurochir (Wien). 2016 Mar;158(3):589-94. doi: 10.1007/s00701-015-2678-z. Epub 2016 Jan 7. PubMed PMID: 26743916.
2)
Guan J, Riva-Cambrin J, Brockmeyer DL. Chiari-related hydrocephalus: assessment of clinical risk factors in a cohort of 297 consecutive patients. Neurosurg Focus. 2016 Nov;41(5):E2. PubMed PMID: 27798986.
3)
Pereira EA, Magdum SA. Foramen magnum decompression - from hygromas to hydrocephalus. Br J Neurosurg. 2016 Jun;30(3):355. doi: 10.3109/02688697.2016.1173198. Epub 2016 Apr 21. PubMed PMID: 27100816.
4)
Elton S, Tubbs RS, Wellons JC 3rd, Blount JP, Grabb PA, Oakes WJ. Acute hydrocephalus following a Chiari I decompression. Pediatr Neurosurg. 2002 Feb;36(2):101-4. PubMed PMID: 11893893.
5)
Prasad GL, Menon GR. Coexistent Supratentorial and Infratentorial Subdural Hygromas with Hydrocephalus After Chiari Decompression Surgery: Review of Literature. World Neurosurg. 2016 Sep;93:208-14. doi: 10.1016/j.wneu.2016.06.025. Epub 2016 Jun 16. Review. PubMed PMID: 27319314.
6)
Filis AK, Moon K, Cohen AR. Symptomatic Subdural Hygroma and Hydrocephalus following Chiari I Decompression. Pediatr Neurosurg. 2009;45(6):425-8. doi: 10.1159/000270159. Epub 2009 Dec 24. PubMed PMID: 20051703.
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