Remote cerebellar hemorrhage
It can be rarely observed as a complication of spine surgery.
Remote cerebellar hemorrhage after spine surgery
Sturiale et al. performed a comprehensive review, collecting all cases of RCH after spine surgery reported in literature in order to identify the procedures most frequently associated with RCH and the possible risk factors. They assessed percentages of incidence and 95 % confidence interval of all demographic, neuroradiological, and clinical features. Univariate and multivariate analyses were used to evaluate their association with outcome. They included 44 articles reporting 57 patients with mean age of 57.6 ± 13.9 years and a male/female ratio of 23/34. A RCH was more frequently reported as a complication of decompressive procedures for spinal canal stenosis, particularly when associated with instrumented fusion, followed by spinal tumor debulking and disc herniation removal. In the majority of cases, RCH occurrence was characterized by progressive impairment of consciousness, whereas some patients complained non-specific symptoms. Coagulation disorders, hypertension, and placement of postoperative subfascial drainages were the most frequently reported risk factors. The occurrence of intraoperative dural lesions was described in about 93 % of patients. Zebra sign was the most common bleeding pattern (about 43 % of cases) followed by parenchymal hematoma (37.5 %) and mixed hemorrhage (about 20 %). Impairment of consciousness at clinical onset and intake of anticoagulants/antiplatelets appeared associated with poor outcome at univariate analysis. However, more than 75 % of patients showed a good outcome and a RCH often appeared as a benign and self-limiting condition, which usually did not require surgical treatment, but only prolonged clinical surveillance, unless of the occurrence of complications 4)
Its pathophysiology still remains unknown.
The precise mechanism of cerebellar hemorrhage following supratentorial burr hole drainage of CSDH is suspected to be multifactorial. Firstly, a history of previous hypertension and transient hypertensive peaks during the recovery period have been considered to be important factors 5) 6).
This idea is based on the fact that arterial hypertension is the most common cause of spontaneous cerebellar hemorrhage. However, only two out of nine patients (22%), reported in the literature, had a history of hypertension and in one out of them the preoperative blood pressure was consistently normal with antihypertensive drugs. Moreover all patients had perioperative normal blood pressure and only in two cases an elevation of blood pressure was reported postoperatively 7).
Another major cause of spontaneous cerebellar hemorrhages is disturbed blood coagulation, which has been considered as well to be a relevant predisposing factor for postoperative cerebellar hemorrhages 8).
Another proposed mechanism for the development of RCH is that expansion of CSF spaces after surgical removal of CSDH increases mobility of the intracranial structures. Moreover, CSF overdrainage may lead to a downward displacement of the cerebellum. These above mentioned mechanisms may cause stretching and possible tearing of the superior vermian veins leading to RCH.
Furthermore, continuous CSF drainage, intraoperatively as well as postoperatively, could even increase the transtentorial pressure gradient leading to rupture of the small supracerebellar veins and capillary bed with venous bleeding as a consequence. A massive air reflux into the cranial cavity through the drainage tube may pose an additional risk 9).
It shows a characteristic bleeding pattern defined “zebra sign”.
Three patients with RCH after three different procedures: burr hole trephination and chronic subdural hematoma evacuation of bilateral cerebral convexity with subsequent subdural drain insertion, external lumbar cerebrospinal fluid drainage for thoracic endovascular aortic repair, and combined bypass surgery for moyamoya disease 10).
Huang et al., report five cases of RCH following cervical spinal surgery, and summarize another seven similar cases from the literature. Dural opening with cerebrospinal fluid hypovolemia seems to be an important factor contributing to RCH following cervical spinal surgery. As other authors have proposed, surgical positioning may be another factor contributing to RCH. RCH is thought to be hemorrhagic venous infarction, resulting from the stretching occlusion of the superior cerebellar vein by the cerebellar sag effect. Either intraoperative CSF loss or a postoperative cerebrospinal fluid drainage from drainage may cause cerebellar sag, further resulting in RCH. RCH is usually self-limiting, and most patients with RCH have an optimal outcome after conservative treatment. Severe cases that involved surgical intervention because of evidence of brainstem compression or hydrocephalus also had acceptable outcomes, compared to spontaneous CH. It has been suggested that one way to prevent RCH is to avoid extensive perioperative loss of CSF, by paying attention to surgical positioning during spinal surgery. Huang et al also underline the importance of early diagnosis and CSF expansion in the early treatment of RCH 11).