Complication
Predisposing factors
Preventive techniques
CSF leak/pseudomeningocele
Hydrocephalus wound infection
Clean cuts to structurally important tissue (fascia, dura)
Avoid diathermy to same
Complete dural closure using galea graft or substitute if it cannot be achieved primarily
Y- or T-shaped incision in fascia just below the inion to assist in a tight closure
Careful reconstruction of the normal planes
Replacement of the bone flap (craniotomy vs. craniectomy)
Minimize dead space in muscular layers
Treat hydrocephalus
Blood loss
Higher risk in infants with low blood volume
Appropriate positioning to prevent venous hypertension
Use of a Colorado needle in infants and young children
Control of hemostasis as bleeding occurs
Active control of the venous sinuses (occipital and circular sinuses) at dural opening
Judicious use of bipolar and other hemostatic techniques during tumor removal
Minimization of cerebellar retraction, use of gravity or otherwise, especially superiorly and superolaterally to the cerebellum
Hydrocephalus
Preoperative hydrocephalus
Avoid opening into CSF spaces if possible (easier with JPAs as they are mostly intra-axial tumor that do not extend into the fourth ventricle)
Minimize blood contamination of subarachnoid space/cisterna magna
Careful monitoring of signs of hydrocephalus
Neurological deficit/cerebellar mutism
Large tumors
Gentle handling of normal neural tissue
Midline tumors
Avoid retraction of normal neural tissue
Minimize use of diathermy especially near peduncles/brainstem
Identify normal structures early
Cerebellar mutism is a disturbing complication, more commonly seen in younger patients, and with larger midline tumors that extend into the fourth ventricle. Originally reported in 1985 by Rekate et al. and Yonemasu, cerebellar mutism may occur in as many as 30 % of patients after resection of a cerebellar tumor [4, 11, 18, 21]. It is thought to be less common in patients with cerebellar pilocytic astrocytomas. The symptoms may last for weeks to months with a gradual return of speech that is often dysarthric as it improves. Persistent cognitive and verbal deficits are common [11, 19].
Longer-term consequences including learning difficulties, motor planning, as well as ongoing cerebellar motor symptoms may be due to direct cerebellar injury. Patients with preoperative deficits are more likely to have postoperative deficits. These may affect a child’s learning abilities, and early intervention should be organized to maximize learning.
Death is, thankfully, rare with modern techniques and is reported in <1–5 % of patients in most series (Dirven, Villarejo, DiRocco). In Villarejo’s series, perioperative mortality was 17.5 % prior to 1974 and 3.2 % after 1974. DiRocco notes that in more modern series, mortality is approaching zero.
27.8 Surgical Outcomes
The most important prognostic factor in the management of cerebellar astrocytomas is the extent of surgical resection [2, 20]. Complete resection for juvenile pilocytic astrocytoma affords a nearly 100 % long-term survival rate compared with the overall 10 year survival rate of 65. Gross total resection, as judged by an immediate postoperative MRI, occurs in 60–70 % of cases [2, 8, 12]. Location is a good determinant of how easily a GTR may be achieved, with Akay’s series describing a higher percentage in patients with single hemispheric lesions. The extent of resection is often overestimated by the operating surgeon [8]! This is reflected in Desai’s series in which the surgeon reported an 80 % incidence of GTR, while this was seen in only 70 % of postoperative scans [6].
It is not surprising then that factors which limit the resection, such as the size and extent of the tumor, brainstem invasion, leptomeningeal spread or multifocal disease, are associated with a worse prognosis. Thus, the recurrence rates in patients with a gross total resection are of the order of 2–5 %, while it is 42–45 % in patients with subtotal removal of tumor [8, 12]. In patients with residual tumor, about half progress, and the rest remain static or regress with time [8]
The histology of the tumor affects prognosis. In Desai’s series of cerebellar astrocytomas, 57 % had pilocytic astrocytomas, 35 % had low-grade fibrillary astrocytomas, and 8 % had high-grade astrocytomas. Pilocytic tumors had a much better long-term survival. This has not been confirmed in all series. There is great variability in the biological behavior of the pilocytic subtype in itself. Some authors believe that cystic tumors carry a better prognosis than solid tumors [15]. At present there is still little information explaining the variable behavior of pilocytic tumors, which, while generally benign can occasionally behave in a malignant fashion, may transform later in to malignant tumors [12] or which may regress.
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