Acute obstructive hydrocephalus associated with infratentorial subdural hygromas complicating Chiari malformation Type I decompression

Abstract

Obstructive hydrocephalus complicating foramen magnum decompression (FMD) for a Chiari malformation (CM) Type I is rare. Two female patients (17 and 55 years old) presented with strain-related headaches. In both cases magnetic resonance (MR) imaging studies confirmed a CM Type I, which was accompanied by syringomyelia in one case. Both patients underwent uncomplicated FMD with good initial recovery. Unfortunately, conditions in both patients deteriorated, with severe headaches occurring between Days 5 and 6 post-FMD. Decreased consciousness occurred in one case. In both patients, computerized tomography scanning demonstrated an acute obstructive hydrocephalus associated with bilateral infratentorial extraaxial fluid collections (EAFCs). In addition, left parafalcine and convexity EAFCs were present in one case. An emergency external ventricular drain was required in one patient, with delayed conversion to a ventriculo-peritoneal shunt. Spontaneous resolution occurred in the other patient without neurosurgical intervention. In both cases, MR imaging confirmed that each EAFC was subdural, resembled cerebrospinal fluid (CSF), and had distorted the superior cerebellum anteroinferiorly. Despite upper fourth ventricle/aqueduct compromise in one case, normal aqueduct flow artifacts were apparent on examination. All EAFCs resolved spontaneously. Obstructive hydrocephalus complicating FMD is rare but invariably associated with infratentorial EAFCs, which were confirmed to be subdural hygromas in this report. The authors assert that hydrocephalus results from upper fourth ventricle/aqueduct compromise as a result of CSF subdural dissection following a pinhole arachnoid tear on durotomy. Because such hygromas spontaneously resolve, permanent shunt insertion should be avoided.

Infratentorial hygroma secondary to decompressive craniectomy after cerebellar infarction

“…This technique had been published before with the same good result 3 . Up to date six cases of symptomatic subdural hygromas in adults have been reported by different authors 1,2,4,5 , all of them secondary to posterior fossa decompression. Five patients were treated for Chiari malformation Type I (CM-I) and one patient presented a hemangioblastoma 5 .…”

Subacute Subdural Hygroma and Presyrinx Formation After Foramen Magnum Decompression With Duraplasty for Chiari Type 1 Malformation -Case Report-

“…4,9,12,13) Hygroma become symptomatic from 5 to 21 days after FMD in all cases, usually within 14 days, suggesting the hygroma started early after FMD. …”

“…9) The presyrinx state developed rapidly, so the CSF flow around the foramen magnum seemed to be disturbed severely. Since ventricular drainage would exaggerate the pressure difference between the intracranial and intraspinal spaces, and worsen the presyrinx, reoperation of the duraplasty with removal of the underlying arachnoid membrane was performed.…”

“…2,6) FMD with duraplasty may be more effective and necessary in some cases, 3,10) but is associated with various complications. 1,7,9,11) CSF leakage after FMD with duraplasty is one of the most common complications. Subdural hygroma after posterior fossa surgery with dural opening is not rare.…”

“…14) However, subdural hygroma and hydrocephalus are rare sequelae of FMD with duraplasty. 4,9,[11][12][13] We experienced a case of subdural hygroma followed by the development of hydrocephalus and presyrinx after uneventful FMD with duraplasty. Reoperation with wide opening of the arachnoid membrane resulted in a rapid resolution of all pathological findings including presyrinx.…”