Journal of Pediatric Rehabilitation Medicine: An Interdisciplinary Approach 7 (2014) 323–331 DOI 10.3233/PRM-140302 IOS Press
323
Neurosurgical care of pediatric brain tumor patients in a rehabilitation unit J. Gordon McComba,b,∗ and Stephanie L. Da Silvaa a
Division of Neurosurgery, Children’s Hospital Los Angeles, CA, USA Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA b
Accepted 17 May 2013
Abstract. As brain tumor patients are transferred to a rehabilitation unit in a stable condition, subsequent neurosurgical involvement is needed to address later developing complications. Problems of cerebrospinal fluid circulation are the most common and include shunt malfunction. Infection is the next in frequency, with wound and shunt infection the most likely. Bleeding rarely occurs, especially acutely, and is more apt to be seen with chronic subdural hematomas. Keywords: Neurosurgical care, rehabilitation, pediatric brain tumor, complications, CSF diversion
1. Introduction Most neurosurgical involvement with pediatric brain tumor patients occurs before the patient is transferred to the rehabilitation unit. Neurosurgical input at the rehabilitation stage is mainly to address complications. The vast majority of complications involve cerebrospinal fluid (CSF) circulation, infection, and bleeding. This paper will cover the neurosurgical diagnosis and management of these entities.
2. Cerebrospinal fluid circulation Impairment of CSF circulation is the most common neurosurgical problem encountered in the rehabilitation setting. Many patients with brain tumors, especially those in whom the tumor is located in the posterior fossa, present with hydrocephalus (Figs 1A and B). If the hydrocephalus is acute and the patient is ex∗ Corresponding author: J. Gordon McComb, 1300 N. Vermont Ave. Doctor’s Tower, Suite 1006, Los Angeles, CA 90027, USA. Tel.: +1 323 361 2169; Fax: +1 323 361 3101; E-mail: gmccomb@ chla.usc.edu.
periencing rapid deterioration, an external ventricular drain (EVD) will urgently be placed upon admission to the hospital (Figs 2 and 3) [1,2]. If an EVD has not been inserted preoperatively, it may be placed during the operative procedure to excise a brain tumor. Draining CSF externally prevents CSF build-up and associated increased intracranial pressure [3]. If CSF drainage is impaired, central nervous system deterioration or wound breakdown may occur. Removing red blood cells and the debris from tissue breakdown may decrease the percentage of patients that need permanent CSF diversion. An attempt is made to wean the patient from the EVD. If successful, the EVD is removed, and, if not, a shunt is placed, the most frequent type being a ventriculoperitoneal shunt. Consideration can also be given to doing an endoscopic third ventriculostomy (ETV) if the obstruction to CSF flow occurs within the ventricular system. Doing so allows CSF to egress via a hole in the floor of the third ventricle to reach the subarachnoid space. If successful, this obviates the need to insert a shunt. All of the procedures mentioned above occur before the patient arrives in the rehabilitation unit. When patients with what was wrongly assumed to be resolution of abnormal CSF circulation are transferred to the rehabilitation unit, one problem can be the
c 2014 – IOS Press and the authors. All rights reserved 1874-5393/14/$27.50
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J.G. McComb and S.L. Da Silva / Neurosurgical care of pediatric brain tumor patients in a rehabilitation unit
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Fig. 1. A: A 3-year-old female with enormous hydrocephalus. Fortunately, we rarely see this degree of hydrocephalus and are better able to manage this problem, which is one of the most frequent secondary effects of brain tumors in the pediatric population. B: Head circumference of 93 cm, which is well above normal. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/PRM-140302)
Fig. 2. T2-weighted coronal MRI of a 7-year-old female with a posterior fossa mass with an EVD that has been placed to address the acute hydrocephalus. The arrow shows the ventricular catheter in the frontal horn of the right lateral ventricle. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ PRM-140302)
Fig. 3. Operating room picture of an infant with an EVD in place, about to undergo removal of a pineal location tumor. (Colours are visible in the online version of the article; http://dx.doi.org/ 10.3233/PRM-140302)
formation of a pseudomeningocele due to progressive ventricular enlargement and/or abnormal collections of CSF in the subarachnoid space (SAS), subdural space (SDS), epidural space (EDS), subgaleal space (SGS), or at the posterior fossa operative site. Another problem is that of CSF leakage. Also discussed are shunts
2.1. Progressive hydrocephalus
and ventricular access devices.
The clinical picture of a child with progressive hydrocephalus can be subtle and easily overlap with and be attributed to the anticipated postoperative state. It can consist of the patient being irritable, sleeping more,
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Fig. 4. A: T2-weighted contrast axial MRI demonstrated pre-operative pineal location atypical teratoid rhabdoid tumor and associated hydrocephalus. B: T2-weighted contrast axial MRI following tumor resection showing frontal subdural (*) and posterior epidural (arrow) space CSF collections. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/PRM-140302)
being less engaged, having less energy, feeling poorly, and not progressing to recovery as well as anticipated. If the hydrocephalus is insidious, it may not be diagnosed until increased ventricular size is noted on a follow-up computerized tomography (CT) or magnetic resonance imaging (MRI) [4]. In addition to ventricular enlargement secondary to increased resistance of CSF drainage, such can also occur as a result of large doses of glucocorticoids, chemotherapy, and radiation therapy. Various MRI sequences may be helpful in establishing causality, especially with serial imaging.
some of this may dissipate with subsequent brain growth, but this is less likely in older patients.
2.2. Subarachnoid space CSF collection
EDS collection of CSF is rarely seen as a problem, as the dura mater is adherent to the bone beyond the operative site and limits the expansion of the fluid collection. If such a fluid collection does occur and is symptomatic, it is treated in a fashion similar to a CSF buildup in either the SAS or SDS (Figs 4A&B).
A cortical or corpus callosal incision used for tumor removal provides a pathway for ventricular CSF to reach the SAS [5]. If CSF drainage resistance is higher in the ventricles than in the SAS, the CSF will be preferentially directed to the SAS, where it can accumulate. If the CSF build-up is causing a progressive mass-effect associated with clinical symptoms, a CSF-diverting shunt or ETV is needed. In patients with long-standing and very slowly progressive hydrocephalus secondary to a brain tumor, the ventricular size can become quite large. These patients can be macrocephalic, and as a result a cranial vault/brain disproportion exists. If ventricular size is reduced, CSF accumulates in the SAS. If the CSF in the SAS is diminished, the ventricles enlarge. In younger patients,
2.3. Subdural space CSF collection The same factors apply to SDS CSF accumulation as with SAS CSF accumulation, and in fact the SAS and SDS spaces are often in communication in this circumstance. The treatment is the same for both. 2.4. Epidural space CSF collection
2.5. Subgaleal space CSF collection In this instance, the source of fluid is generally CSF escaping from the ventricles via a cortical or corpus callosum incision pathway, the fluid having traversed the SAS, the SDS, and the EDS to reach the SGS. SGS CSF build-up occurs at the site of a supratentorial operation and indicates that the path of least resistance is to the SGS. As the galea easily separates from the pericranium, a large collection covering most of the
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Fig. 5. T2-weighted sagittal MRI demonstrated postsurgical pseudomeningocele (*) following a posterior fossa craniotomy and resection of a 3-year-old female’s pilocytic astrocytoma. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ PRM-140302)
hemisphere can develop. Serial fluid aspiration is the initial treatment. Head wrapping can be attempted, but it can be difficult to keep the wrap in place and children will often repeatedly remove it. Also, the pressure dressing needs to be carefully applied so as to not damage the scalp. The wrapping must be redone multiple times during a 24-hour period. Recently, we have tried the use of a tighter-fitting skull cap (Do-rag, Doorag, Du-rag), but have not had enough experience to attest to its effectiveness. These measures are temporizing with the hope that the CSF drainage resistance will diminish in a limited time. The fluid should also be periodically sent for analysis, as infection may be the underlying cause of the CSF circulation problem. The tapping of shunts, subgaleal fluid collections, and pseudomeningoceles is limited to trained neurosurgical personnel and, by doing so, renders the possibility of causing an infection to a highly unlikely event. 2.6. Pseudomeningocele Pseudomeningocele usually designates an abnormal CSF collection in the soft tissues overlying the posterior fossa and upper cervical spine (Fig. 5). As at least half of pediatric brain tumors occur in the posterior fossa, this is a common problem. Replacing the bone flap has been shown to reduce the severity of the
pseudomeningocele [6]. Various dural closure methods are ineffective in preventing this complication; if increased resistance to CSF drainage is present, dural closure methods will not prevent leakage of CSF into the overlying soft tissues [3]. As with SGS fluid collection, the initial management is serial tapping in hopes that the problem will resolve before the incision leaks CSF or breaks down. If the wound is threatened, even with serial tapping, CSF diversion is often indicated. It is recommended that aspirated fluid be periodically analyzed for cell count with differential, gram stain, and culture in order to exclude infection. As the CSF is in contact with the surrounding soft tissues, an elevated white blood cell (WBC) count of 100 or more is a usual finding. WBC numbers in the thousands would make infection much more likely. The gram stain can be helpful, but false positives and negatives may arise. The protein content will be high secondary to fluid contact with the tumor bed and surrounding soft tissues. Glucose level is not helpful in making a diagnosis of infection. If the aerobic culture is negative and infection is still suspected, the fluid should be sent for anaerobes and fungi, especially if the patient is immunosuppressed. Wrapping the head to treat a pseudomeningocele is very difficult to accomplish and of doubtful benefit. Pseudomeningoceles usually diminish in size with time, although occasionally one sees a patient with a persistent fluid collection, which is of little concern. 2.7. CSF Leakage CSF leakage at the incision site occurs in response to pressure or infection. Increased resistance of CSF drainage results in fluid build-up at the operative site, putting pressure on the wound. That, in turn, adversely affects wound healing. Infection of the wound or CSF can also lead to wound breakdown and CSF leakage. Conversely, CSF leakage can lead to wound or CSF infection [3]. The initial treatment for CSF leakage is often bedside suturing. As a temporizing measure, serial fluid aspirations may give time for CSF drainage pathways to improve, thereby reducing the CSF build-up at the operative site. Sometimes a CSF-diverting shunt is inserted. If it is being serially aspirated, CSF buildup at the wound site should be periodically analyzed for infection. Another temporizing measure of if the hydrocephalus is communicating is to place a lumbar CSF drain [3,4]. Another CSF leakage site is the skull base, due to various approaches to tumors in these locations with
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Fig. 8. Example of the built-in reservoir sitting on the calvarium in the subgaleal space used for tapping the shunt. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ PRM-140302) Fig. 6. A non-contrast sagittal CT image of a 3-year-old male with a pituitary location CSF leak demonstrating pneumocephalus (arrows). (Colours are visible in the online version of the article; http:// dx.doi.org/10.3233/PRM-140302)
A
B
Fig. 7. Despite clinical symptoms of raised intracranial pressure consistent with shunt malfunction, the CT scan (A) of this child did not show increase in ventricular size compared with a previous CT scan (B) without any clinical evidence of shunt malfunction. Approximately 10% of patients with operative proven shunt malfunction do not show increase in ventricular size.
the transsphenoidal route being the most frequent. The patient may have low-pressure headaches or symptoms of meningitis. The ease of diagnosis of a CSF leak varies, with the most obvious being CSF dripping from the nose in a head-down position. Nasal stuffiness or sensations of fluid draining down the back of the throat are other indicators. Imaging with a CT or MRI may show pneumocephalus (Fig. 6) or fluid in the nasal sinuses, especially the sphenoid. In questionable cases, fluid obtained (usually from the nose) can be analyzed for beta-2-transferrin, a substance that is almost exclusively found in CSF.
Fig. 9. One method to help determine the possibility of shunt malfunction is to tap a reservoir built into the system. CSF can also be obtained for evaluation of possible shunt infection. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ PRM-140302)
Skull base CSF leaks in the immediate postoperative period are dealt with before the patient is transferred to the rehabilitation unit. Occasionally, a delayed leak will occur, requiring the patient to be transferred back to the hospital inpatient service. Management strategies include placing a lumbar drain or re-exploring and packing the operative site. 2.8. Shunts The best way to avoid shunt problems is to not insert a shunt. Shunting should be used only if all other measures fail. Shunt complications in the rehabilitation setting are overwhelmingly secondary to obstruction or infection. The location of the obstruction within
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Fig. 10. A: CSF-diverting shunt placement secondary to hydrocephalus and enlarged ventricles. B: Development of chronic subdural hematoma following CSF diversion. An acute component indicating recent bleeding is also present (arrow). (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/PRM-140302)
the shunt system varies to a degree according to the type of hardware used, but the most frequent site is the ventricular catheter [1]. Obstruction is diagnosed with CT or MRI scans to assess ventricular size, although about 10% of the time the ventricles do not enlarge even when the shunt is completely occluded (Fig. 7) [7]. Shunt function can also be assessed by tapping the reservoir built into the system (Figs 8 and 9). Determining whether a shunt is functioning satisfactorily can, at times, be very difficult, and is complicated further in the postoperative patient whose symptoms can just as easily be related to the effects of tumor, the surgery to remove it, and/or adjuvant therapy. The clinical symptoms of CSF over-drainage by a shunt are rare in the pediatric population. CSF under-drainage is usually the result of a partial or complete shunt obstruction. Programmable shunt valves are not routinely used at our institution as they have not been shown to provide benefit nor to lower the incidence of complications associated with impaired CSF drainage [8–11]. The programmable valves currently in use have to be reset after an MRI study, although newer ones are being developed to overcome this problem [12]. The programmable valves also produce a significant artifact on MRI studies that may interfere with imaging interpretation [13,14]. 2.9. Ventricular access devices Ventricular access devices are often called Ommaya reservoirs, as the first one to be used was developed
by a neurosurgeon of that name. There are a number of ventricular access devices of which the Ommaya is but one. These devices consist of a ventricular catheter attached to a reservoir that sits on the calvarium in the subgaleal space (Fig. 9). They are accessed in the same way as a reservoir contained in a CSF-diverting shunt. The indication for placement of this device is usually to administer intraventricular chemotherapy. The complications are the same as those with a shunt – obstruction and infection. The likelihood of causing an infection with percutaneous tapping of the reservoir should be rare if done correctly.
3. Infections As the symptoms of infection may take some time to develop, the presence of such may not become evident until after the brain tumor patient is transferred to the rehabilitation unit. 3.1. Scalp Scalp infections are readily apparent and are more likely to develop if the wound is under tension that interferes with healing. The most frequent cause for the wound to be under tension is CSF buildup secondary to impairment of CSF drainage. Impairment of CSF drainage can also indicate CSF infection, which may also result in increased resistance to CSF drainage.
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Fig. 11. Skin breakdown along shunt tract leading to exposure of shunt hardware, necessitating shunt removal and replacement. (Colours are visible in the online version of the article; http://dx.doi. org/10.3233/PRM-140302)
CSF buildup can be reduced with serial tapping or the placement of a CSF diverting shunt or ETV after establishing that no infection is present. If an infection is present, it may be necessary to place an EVD. Stitch abscesses can be treated with local wound care, i.e., regularly cleaning and wound debridement. Some advocate the application of antibiotic ointment, and systemic antibiotics are usually not indicated unless the patient is immunocompromised. More significant infections may require operative debridement and either primary or delayed closure. If the patient has a shunt, care must taken not to put undue pressure on the overlying scalp that could lead to its breakdown and exposure of the hardware. This is especially true in the younger patient whose scalp is thin. If scalp necrosis occurs over the shunt, it is usually at the site of the valve, as that part of the shunt is the most protuberant. Skin breakdown over the shunt requires its removal and subsequent replacement, including the use of an EVD if the CSF is infected (Fig. 11). 3.2. Bone Infection can occur in the segment of bone removed to gain surgical access to the brain tumor, the instance of which being less in the pediatric population as compared to adults. Osteomyelitis of the bone flap may develop over a protracted period of time and is often manifested by delayed wound breakdown, even months later, with the presence of chronic granulation tissue at the incision site [15]. A more virulent infection may cause pus drainage from the wound. The diagnosis is usually made with a CT scan that shows
Fig. 12. Bone window CT scan demonstrating osteomyelitis of the bone flap with adjacent soft tissue swelling.
the typical moth-eaten appearance of the bone flap (Fig. 12). Treatment consists of removing the infected bone flap and administering systemic antibiotics for a prolonged period. If the bony defect is cosmetically significant or sufficient in size to be a protective issue, this can be addressed by a cranioplasty after the infection has been cleared. 3.3. Intracranial Abscesses can be epidural, subdural, within the ventricles, or intraparenchymal, and signs and symptoms vary by location of the abscess (Figs 13A&B). Treatment often requires surgical drainage of the abscess with a prolonged course of appropriate antibiotics to follow. A heightened degree of vigilance is warranted in the immunosuppressed patient. Fortunately, intracranial abscess formation is infrequent in the rehabilitating brain tumor patient. 3.4. Shunts Shunt infections vie with wound infection for frequency. The clinical evidence for a shunt infection may be 1) readily apparent or 2) completely absent and only manifested by shunt obstruction, which would give rise to symptoms of raised intracranial pressure. Meningeal signs are usually absent, as the infected CSF is often confined to the ventricles and/or does not reach the subarachnoid space. Abdominal tenderness with
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Fig. 13. A: Contrast sagittal T1 MRI of a 9-year-old female with a recurrent optic pathway glioma demonstrating a post-operative epidural abscess requiring surgical intervention. B: Intra-operative abscess with pus accumulation in the epidural space (Fig. 13A). Treatment also necessitated removal of the bone flap. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/PRM-140302)
evidence of peritonitis may be evident or completely lacking. Redness and swelling along the shunt tract and at the insertion incision sites are only occasionally present. Diagnosis is made by tapping the shunt and sending the CSF for analysis [1]. The most reliable confirmation of infection is bacteria growing on the agar plates and in the broth on more than one CSF specimen. Broth only positive cultures can often be due to contamination. The degree of CSF leukocytosis and the differentiation of the type of WBCs present will vary depending upon how long the infection has been present and the virulence of the organism. The gram stain is helpful, but false positives and negatives are sometimes encountered. It may also be necessary to send CSF cultures for anaerobes and fungi if the aerobic cultures are negative and infection is still suspected [16]. Treatment consists of removing the shunt and placing an EVD. The shunt can then be re-inserted approximately 1–2 weeks after the first sterile CSF culture is obtained [1]. Glucose and protein levels are not particularly useful in the diagnosis of infection or following the response to treatment, and thus there is no reason to obtain these tests. Of shunt infections, the vast majority occurs at the time of insertion or revision and is reported to be up to 15%. If the shunt is inserted or revised without infection, the likelihood of it becoming infected at a later date is remote. For a patient who has a shunt in place for many years without symptoms referable to the shunt, the chance of an unexplained fever being secondary to a shunt infection is quite unusual. If an
infection does occur, it is usually secondary to sepsis or peritonitis such as following a ruptured appendix. A patient who is significantly immunosuppressed can also be at more risk for developing a shunt infection after its insertion. 4. Bleeding By the time the postoperative brain tumor patient is transferred to the rehabilitation unit, the likelihood of new hemorrhaging is very rare. An exception is if chemotherapy significantly interferes with the normal clotting mechanisms. A more common bleeding problem is the development of chronic subdural hematomas. If small and asymptomatic, nothing needs be done except follow-up imaging. Occasionally, chronic subdural hematomas can develop following CSF diversion for hydrocephalus, especially if the ventricles were large before CSF diversion or if there is a brain/calvarial vault disproportion (Figs 10A, B). Even if a hematoma is fairly large, action is not needed if the patient has no symptoms. However, if the collection continues to increase in size and/or the patient is symptomatic, treatment consists of burr hole drainage and possible placement of a subdural peritoneal shunt. 5. Conclusion Most neurosurgical complications encountered in the rehabilitation setting involve problems with CSF
J.G. McComb and S.L. Da Silva / Neurosurgical care of pediatric brain tumor patients in a rehabilitation unit
circulation. Modern imaging techniques have greatly aided the diagnosis and treatment of impaired CSF drainage. The direct effects of increased resistance to CSF absorption are raised intracranial pressure affecting neurological function and producing unwanted CSF collections that impair wound healing or lead to wound breakdown. Shunt malfunction and/or infection is a potential problem that may be obvious or very difficult to diagnose. CSF infection is more common if a shunt is present and is best diagnosed by CSF cultures, as other indices are much less reliable. Other locations of central nervous system infection are much less frequent. Acute hemorrhage is a rare complication; more commonly encountered is bleeding associated with a chronic subdural hematoma.
[5]
[6]
[7]
[8]
[9]
[10]
Conflict of interest The authors have no conflict of interest to declare.
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McComb JG. Methods of Cerebrospinal Fluid Diversion. In: Apuzzo MLJ, editor. Surgery of the Third Ventricle. 2nd ed. Baltimore: Williams & Wilkins, 1998, pp. 607-33. Bognar L, Borgulya G, Benke P, Madarassy G: Analysis of CSF shunting procedure requirement in children with posterior fossa tumors. Childs Nerv Syst. 2003; 19(5-6): 332-36. Steinbok P, SInghal A, Mills J, Cochrane DD, Price AV: Cerebrospinal fluid (CSF) leak and pseudomeningocele formation after posterior fossa tumor resection in children: A retrospective analysis. Childs Nerv Syst. 2007; 23(2): 171-74; discussion 175. Due-Tonnessen BJ, Helseth E: Management of hydrocephalus in children with posterior fossa tumors: Role of tumor surgery.
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Pediatr Neurosurg. 2007; 43(2): 92-6. Equchi S, Aihara Y, Hori T, Okada Y. Postoperative extraaxial cerebrospinal fluid collection – its pathophysiology and clinical management. Pediatr Neurosurg. 2011; 47(2): 125-32. doi: 10.1159/000330543. Gnanalingham KK, Lafuente J, Thompson D, Harkness W, Hayward R: Surgical procedures for posterior fossa tumors in children: Does craniotomy lead to fewer complications than craniectomy? J Neurosurg. 2002; 97(4): 821-26. McNatt SA, Kim A, Hohuan D, Krieger M, McComb JG. Pediatric shunt malfunction without ventricular dilatation. Pediatr Neurosurg. 2008; 44(2): 128-3. Drake JM, Kestle JR, Milner R, Cinalli G, Boop F, Piatt J Jr, et al: Randomized trial of cerebrospinal fluid shunt valve design in pediatric hydrocephalus. Neurosurgery. 1998; 43(2): 294303. Pollack IF, Albright AL, Adelson PD. A randomized controlled study of a programmable shunt valve versus a conventional valve for patients with hydrocephalus. Neurosurgery. 1999; 45(6): 1399-1408; discussion 1408-11. Notarianni C, Vannemreddy P, Caldito G, Bollam P, Wylen E, Willis B, et al. Congenital hydrocephalus and ventriculoperitoneal shunts: influence of etiology and programmable shunts on revisions. J Neurosurg Pediatr. 2009; 4(6): 547-52. Mangano FT, Menendez JA, Habrock T, Narayan P, Leonard JR, Park TS, et al. Early programmable valve malfunctions in pediatric hydrocephalus. J Neurosurg. 2005; 103(6 Suppl): 501-7. Allin DM, Czosnyka M, Richards HK, Pickard JD, Czosnyka ZH. Investigation of the hydrodynamic properties of a new MRI-resistant programmable hydrocephalus shunt. Cerebrospinal Fluid Res. 2008; 5: 8. doi: 10.1186/1743-8454-5-8. Shellock FG, Wilson SF, Mauge CP. Magnetically programmable shunt valve: MRI at 3-Tesla. Magn Reson Imaging. 2007; 25(7): 1116-21. Mauer UM, Kunz U. More malfunctioning Medos Hakim programmable valves: cause for concern? J Neurosurg. 2011; 115(5): 1047-52. Blumenkopf B, Hartshorne MF: Craniotomy flap osteomyelitis: A diagnostic approach. J Neurosurg. 1987; 66(1): 96-101. Kulkarni AV, Drake JM, Lamberti-Pasculli M: Cerebrospinal fluid shunt infection: A prospective study of risk factors. J Neurosurg. 2001; 94(2): 195-201.
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323
Neurosurgical care of pediatric brain tumor patients in a rehabilitation unit J. Gordon McComba,b,∗ and Stephanie L. Da Silvaa a
Division of Neurosurgery, Children’s Hospital Los Angeles, CA, USA Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA b
Accepted 17 May 2013
Abstract. As brain tumor patients are transferred to a rehabilitation unit in a stable condition, subsequent neurosurgical involvement is needed to address later developing complications. Problems of cerebrospinal fluid circulation are the most common and include shunt malfunction. Infection is the next in frequency, with wound and shunt infection the most likely. Bleeding rarely occurs, especially acutely, and is more apt to be seen with chronic subdural hematomas. Keywords: Neurosurgical care, rehabilitation, pediatric brain tumor, complications, CSF diversion
1. Introduction Most neurosurgical involvement with pediatric brain tumor patients occurs before the patient is transferred to the rehabilitation unit. Neurosurgical input at the rehabilitation stage is mainly to address complications. The vast majority of complications involve cerebrospinal fluid (CSF) circulation, infection, and bleeding. This paper will cover the neurosurgical diagnosis and management of these entities.
2. Cerebrospinal fluid circulation Impairment of CSF circulation is the most common neurosurgical problem encountered in the rehabilitation setting. Many patients with brain tumors, especially those in whom the tumor is located in the posterior fossa, present with hydrocephalus (Figs 1A and B). If the hydrocephalus is acute and the patient is ex∗ Corresponding author: J. Gordon McComb, 1300 N. Vermont Ave. Doctor’s Tower, Suite 1006, Los Angeles, CA 90027, USA. Tel.: +1 323 361 2169; Fax: +1 323 361 3101; E-mail: gmccomb@ chla.usc.edu.
periencing rapid deterioration, an external ventricular drain (EVD) will urgently be placed upon admission to the hospital (Figs 2 and 3) [1,2]. If an EVD has not been inserted preoperatively, it may be placed during the operative procedure to excise a brain tumor. Draining CSF externally prevents CSF build-up and associated increased intracranial pressure [3]. If CSF drainage is impaired, central nervous system deterioration or wound breakdown may occur. Removing red blood cells and the debris from tissue breakdown may decrease the percentage of patients that need permanent CSF diversion. An attempt is made to wean the patient from the EVD. If successful, the EVD is removed, and, if not, a shunt is placed, the most frequent type being a ventriculoperitoneal shunt. Consideration can also be given to doing an endoscopic third ventriculostomy (ETV) if the obstruction to CSF flow occurs within the ventricular system. Doing so allows CSF to egress via a hole in the floor of the third ventricle to reach the subarachnoid space. If successful, this obviates the need to insert a shunt. All of the procedures mentioned above occur before the patient arrives in the rehabilitation unit. When patients with what was wrongly assumed to be resolution of abnormal CSF circulation are transferred to the rehabilitation unit, one problem can be the
c 2014 – IOS Press and the authors. All rights reserved 1874-5393/14/$27.50
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Fig. 1. A: A 3-year-old female with enormous hydrocephalus. Fortunately, we rarely see this degree of hydrocephalus and are better able to manage this problem, which is one of the most frequent secondary effects of brain tumors in the pediatric population. B: Head circumference of 93 cm, which is well above normal. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/PRM-140302)
Fig. 2. T2-weighted coronal MRI of a 7-year-old female with a posterior fossa mass with an EVD that has been placed to address the acute hydrocephalus. The arrow shows the ventricular catheter in the frontal horn of the right lateral ventricle. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ PRM-140302)
Fig. 3. Operating room picture of an infant with an EVD in place, about to undergo removal of a pineal location tumor. (Colours are visible in the online version of the article; http://dx.doi.org/ 10.3233/PRM-140302)
formation of a pseudomeningocele due to progressive ventricular enlargement and/or abnormal collections of CSF in the subarachnoid space (SAS), subdural space (SDS), epidural space (EDS), subgaleal space (SGS), or at the posterior fossa operative site. Another problem is that of CSF leakage. Also discussed are shunts
2.1. Progressive hydrocephalus
and ventricular access devices.
The clinical picture of a child with progressive hydrocephalus can be subtle and easily overlap with and be attributed to the anticipated postoperative state. It can consist of the patient being irritable, sleeping more,
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Fig. 4. A: T2-weighted contrast axial MRI demonstrated pre-operative pineal location atypical teratoid rhabdoid tumor and associated hydrocephalus. B: T2-weighted contrast axial MRI following tumor resection showing frontal subdural (*) and posterior epidural (arrow) space CSF collections. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/PRM-140302)
being less engaged, having less energy, feeling poorly, and not progressing to recovery as well as anticipated. If the hydrocephalus is insidious, it may not be diagnosed until increased ventricular size is noted on a follow-up computerized tomography (CT) or magnetic resonance imaging (MRI) [4]. In addition to ventricular enlargement secondary to increased resistance of CSF drainage, such can also occur as a result of large doses of glucocorticoids, chemotherapy, and radiation therapy. Various MRI sequences may be helpful in establishing causality, especially with serial imaging.
some of this may dissipate with subsequent brain growth, but this is less likely in older patients.
2.2. Subarachnoid space CSF collection
EDS collection of CSF is rarely seen as a problem, as the dura mater is adherent to the bone beyond the operative site and limits the expansion of the fluid collection. If such a fluid collection does occur and is symptomatic, it is treated in a fashion similar to a CSF buildup in either the SAS or SDS (Figs 4A&B).
A cortical or corpus callosal incision used for tumor removal provides a pathway for ventricular CSF to reach the SAS [5]. If CSF drainage resistance is higher in the ventricles than in the SAS, the CSF will be preferentially directed to the SAS, where it can accumulate. If the CSF build-up is causing a progressive mass-effect associated with clinical symptoms, a CSF-diverting shunt or ETV is needed. In patients with long-standing and very slowly progressive hydrocephalus secondary to a brain tumor, the ventricular size can become quite large. These patients can be macrocephalic, and as a result a cranial vault/brain disproportion exists. If ventricular size is reduced, CSF accumulates in the SAS. If the CSF in the SAS is diminished, the ventricles enlarge. In younger patients,
2.3. Subdural space CSF collection The same factors apply to SDS CSF accumulation as with SAS CSF accumulation, and in fact the SAS and SDS spaces are often in communication in this circumstance. The treatment is the same for both. 2.4. Epidural space CSF collection
2.5. Subgaleal space CSF collection In this instance, the source of fluid is generally CSF escaping from the ventricles via a cortical or corpus callosum incision pathway, the fluid having traversed the SAS, the SDS, and the EDS to reach the SGS. SGS CSF build-up occurs at the site of a supratentorial operation and indicates that the path of least resistance is to the SGS. As the galea easily separates from the pericranium, a large collection covering most of the
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*
Fig. 5. T2-weighted sagittal MRI demonstrated postsurgical pseudomeningocele (*) following a posterior fossa craniotomy and resection of a 3-year-old female’s pilocytic astrocytoma. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ PRM-140302)
hemisphere can develop. Serial fluid aspiration is the initial treatment. Head wrapping can be attempted, but it can be difficult to keep the wrap in place and children will often repeatedly remove it. Also, the pressure dressing needs to be carefully applied so as to not damage the scalp. The wrapping must be redone multiple times during a 24-hour period. Recently, we have tried the use of a tighter-fitting skull cap (Do-rag, Doorag, Du-rag), but have not had enough experience to attest to its effectiveness. These measures are temporizing with the hope that the CSF drainage resistance will diminish in a limited time. The fluid should also be periodically sent for analysis, as infection may be the underlying cause of the CSF circulation problem. The tapping of shunts, subgaleal fluid collections, and pseudomeningoceles is limited to trained neurosurgical personnel and, by doing so, renders the possibility of causing an infection to a highly unlikely event. 2.6. Pseudomeningocele Pseudomeningocele usually designates an abnormal CSF collection in the soft tissues overlying the posterior fossa and upper cervical spine (Fig. 5). As at least half of pediatric brain tumors occur in the posterior fossa, this is a common problem. Replacing the bone flap has been shown to reduce the severity of the
pseudomeningocele [6]. Various dural closure methods are ineffective in preventing this complication; if increased resistance to CSF drainage is present, dural closure methods will not prevent leakage of CSF into the overlying soft tissues [3]. As with SGS fluid collection, the initial management is serial tapping in hopes that the problem will resolve before the incision leaks CSF or breaks down. If the wound is threatened, even with serial tapping, CSF diversion is often indicated. It is recommended that aspirated fluid be periodically analyzed for cell count with differential, gram stain, and culture in order to exclude infection. As the CSF is in contact with the surrounding soft tissues, an elevated white blood cell (WBC) count of 100 or more is a usual finding. WBC numbers in the thousands would make infection much more likely. The gram stain can be helpful, but false positives and negatives may arise. The protein content will be high secondary to fluid contact with the tumor bed and surrounding soft tissues. Glucose level is not helpful in making a diagnosis of infection. If the aerobic culture is negative and infection is still suspected, the fluid should be sent for anaerobes and fungi, especially if the patient is immunosuppressed. Wrapping the head to treat a pseudomeningocele is very difficult to accomplish and of doubtful benefit. Pseudomeningoceles usually diminish in size with time, although occasionally one sees a patient with a persistent fluid collection, which is of little concern. 2.7. CSF Leakage CSF leakage at the incision site occurs in response to pressure or infection. Increased resistance of CSF drainage results in fluid build-up at the operative site, putting pressure on the wound. That, in turn, adversely affects wound healing. Infection of the wound or CSF can also lead to wound breakdown and CSF leakage. Conversely, CSF leakage can lead to wound or CSF infection [3]. The initial treatment for CSF leakage is often bedside suturing. As a temporizing measure, serial fluid aspirations may give time for CSF drainage pathways to improve, thereby reducing the CSF build-up at the operative site. Sometimes a CSF-diverting shunt is inserted. If it is being serially aspirated, CSF buildup at the wound site should be periodically analyzed for infection. Another temporizing measure of if the hydrocephalus is communicating is to place a lumbar CSF drain [3,4]. Another CSF leakage site is the skull base, due to various approaches to tumors in these locations with
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Fig. 8. Example of the built-in reservoir sitting on the calvarium in the subgaleal space used for tapping the shunt. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ PRM-140302) Fig. 6. A non-contrast sagittal CT image of a 3-year-old male with a pituitary location CSF leak demonstrating pneumocephalus (arrows). (Colours are visible in the online version of the article; http:// dx.doi.org/10.3233/PRM-140302)
A
B
Fig. 7. Despite clinical symptoms of raised intracranial pressure consistent with shunt malfunction, the CT scan (A) of this child did not show increase in ventricular size compared with a previous CT scan (B) without any clinical evidence of shunt malfunction. Approximately 10% of patients with operative proven shunt malfunction do not show increase in ventricular size.
the transsphenoidal route being the most frequent. The patient may have low-pressure headaches or symptoms of meningitis. The ease of diagnosis of a CSF leak varies, with the most obvious being CSF dripping from the nose in a head-down position. Nasal stuffiness or sensations of fluid draining down the back of the throat are other indicators. Imaging with a CT or MRI may show pneumocephalus (Fig. 6) or fluid in the nasal sinuses, especially the sphenoid. In questionable cases, fluid obtained (usually from the nose) can be analyzed for beta-2-transferrin, a substance that is almost exclusively found in CSF.
Fig. 9. One method to help determine the possibility of shunt malfunction is to tap a reservoir built into the system. CSF can also be obtained for evaluation of possible shunt infection. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ PRM-140302)
Skull base CSF leaks in the immediate postoperative period are dealt with before the patient is transferred to the rehabilitation unit. Occasionally, a delayed leak will occur, requiring the patient to be transferred back to the hospital inpatient service. Management strategies include placing a lumbar drain or re-exploring and packing the operative site. 2.8. Shunts The best way to avoid shunt problems is to not insert a shunt. Shunting should be used only if all other measures fail. Shunt complications in the rehabilitation setting are overwhelmingly secondary to obstruction or infection. The location of the obstruction within
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A
B
Fig. 10. A: CSF-diverting shunt placement secondary to hydrocephalus and enlarged ventricles. B: Development of chronic subdural hematoma following CSF diversion. An acute component indicating recent bleeding is also present (arrow). (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/PRM-140302)
the shunt system varies to a degree according to the type of hardware used, but the most frequent site is the ventricular catheter [1]. Obstruction is diagnosed with CT or MRI scans to assess ventricular size, although about 10% of the time the ventricles do not enlarge even when the shunt is completely occluded (Fig. 7) [7]. Shunt function can also be assessed by tapping the reservoir built into the system (Figs 8 and 9). Determining whether a shunt is functioning satisfactorily can, at times, be very difficult, and is complicated further in the postoperative patient whose symptoms can just as easily be related to the effects of tumor, the surgery to remove it, and/or adjuvant therapy. The clinical symptoms of CSF over-drainage by a shunt are rare in the pediatric population. CSF under-drainage is usually the result of a partial or complete shunt obstruction. Programmable shunt valves are not routinely used at our institution as they have not been shown to provide benefit nor to lower the incidence of complications associated with impaired CSF drainage [8–11]. The programmable valves currently in use have to be reset after an MRI study, although newer ones are being developed to overcome this problem [12]. The programmable valves also produce a significant artifact on MRI studies that may interfere with imaging interpretation [13,14]. 2.9. Ventricular access devices Ventricular access devices are often called Ommaya reservoirs, as the first one to be used was developed
by a neurosurgeon of that name. There are a number of ventricular access devices of which the Ommaya is but one. These devices consist of a ventricular catheter attached to a reservoir that sits on the calvarium in the subgaleal space (Fig. 9). They are accessed in the same way as a reservoir contained in a CSF-diverting shunt. The indication for placement of this device is usually to administer intraventricular chemotherapy. The complications are the same as those with a shunt – obstruction and infection. The likelihood of causing an infection with percutaneous tapping of the reservoir should be rare if done correctly.
3. Infections As the symptoms of infection may take some time to develop, the presence of such may not become evident until after the brain tumor patient is transferred to the rehabilitation unit. 3.1. Scalp Scalp infections are readily apparent and are more likely to develop if the wound is under tension that interferes with healing. The most frequent cause for the wound to be under tension is CSF buildup secondary to impairment of CSF drainage. Impairment of CSF drainage can also indicate CSF infection, which may also result in increased resistance to CSF drainage.
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Fig. 11. Skin breakdown along shunt tract leading to exposure of shunt hardware, necessitating shunt removal and replacement. (Colours are visible in the online version of the article; http://dx.doi. org/10.3233/PRM-140302)
CSF buildup can be reduced with serial tapping or the placement of a CSF diverting shunt or ETV after establishing that no infection is present. If an infection is present, it may be necessary to place an EVD. Stitch abscesses can be treated with local wound care, i.e., regularly cleaning and wound debridement. Some advocate the application of antibiotic ointment, and systemic antibiotics are usually not indicated unless the patient is immunocompromised. More significant infections may require operative debridement and either primary or delayed closure. If the patient has a shunt, care must taken not to put undue pressure on the overlying scalp that could lead to its breakdown and exposure of the hardware. This is especially true in the younger patient whose scalp is thin. If scalp necrosis occurs over the shunt, it is usually at the site of the valve, as that part of the shunt is the most protuberant. Skin breakdown over the shunt requires its removal and subsequent replacement, including the use of an EVD if the CSF is infected (Fig. 11). 3.2. Bone Infection can occur in the segment of bone removed to gain surgical access to the brain tumor, the instance of which being less in the pediatric population as compared to adults. Osteomyelitis of the bone flap may develop over a protracted period of time and is often manifested by delayed wound breakdown, even months later, with the presence of chronic granulation tissue at the incision site [15]. A more virulent infection may cause pus drainage from the wound. The diagnosis is usually made with a CT scan that shows
Fig. 12. Bone window CT scan demonstrating osteomyelitis of the bone flap with adjacent soft tissue swelling.
the typical moth-eaten appearance of the bone flap (Fig. 12). Treatment consists of removing the infected bone flap and administering systemic antibiotics for a prolonged period. If the bony defect is cosmetically significant or sufficient in size to be a protective issue, this can be addressed by a cranioplasty after the infection has been cleared. 3.3. Intracranial Abscesses can be epidural, subdural, within the ventricles, or intraparenchymal, and signs and symptoms vary by location of the abscess (Figs 13A&B). Treatment often requires surgical drainage of the abscess with a prolonged course of appropriate antibiotics to follow. A heightened degree of vigilance is warranted in the immunosuppressed patient. Fortunately, intracranial abscess formation is infrequent in the rehabilitating brain tumor patient. 3.4. Shunts Shunt infections vie with wound infection for frequency. The clinical evidence for a shunt infection may be 1) readily apparent or 2) completely absent and only manifested by shunt obstruction, which would give rise to symptoms of raised intracranial pressure. Meningeal signs are usually absent, as the infected CSF is often confined to the ventricles and/or does not reach the subarachnoid space. Abdominal tenderness with
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A
B
Fig. 13. A: Contrast sagittal T1 MRI of a 9-year-old female with a recurrent optic pathway glioma demonstrating a post-operative epidural abscess requiring surgical intervention. B: Intra-operative abscess with pus accumulation in the epidural space (Fig. 13A). Treatment also necessitated removal of the bone flap. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/PRM-140302)
evidence of peritonitis may be evident or completely lacking. Redness and swelling along the shunt tract and at the insertion incision sites are only occasionally present. Diagnosis is made by tapping the shunt and sending the CSF for analysis [1]. The most reliable confirmation of infection is bacteria growing on the agar plates and in the broth on more than one CSF specimen. Broth only positive cultures can often be due to contamination. The degree of CSF leukocytosis and the differentiation of the type of WBCs present will vary depending upon how long the infection has been present and the virulence of the organism. The gram stain is helpful, but false positives and negatives are sometimes encountered. It may also be necessary to send CSF cultures for anaerobes and fungi if the aerobic cultures are negative and infection is still suspected [16]. Treatment consists of removing the shunt and placing an EVD. The shunt can then be re-inserted approximately 1–2 weeks after the first sterile CSF culture is obtained [1]. Glucose and protein levels are not particularly useful in the diagnosis of infection or following the response to treatment, and thus there is no reason to obtain these tests. Of shunt infections, the vast majority occurs at the time of insertion or revision and is reported to be up to 15%. If the shunt is inserted or revised without infection, the likelihood of it becoming infected at a later date is remote. For a patient who has a shunt in place for many years without symptoms referable to the shunt, the chance of an unexplained fever being secondary to a shunt infection is quite unusual. If an
infection does occur, it is usually secondary to sepsis or peritonitis such as following a ruptured appendix. A patient who is significantly immunosuppressed can also be at more risk for developing a shunt infection after its insertion. 4. Bleeding By the time the postoperative brain tumor patient is transferred to the rehabilitation unit, the likelihood of new hemorrhaging is very rare. An exception is if chemotherapy significantly interferes with the normal clotting mechanisms. A more common bleeding problem is the development of chronic subdural hematomas. If small and asymptomatic, nothing needs be done except follow-up imaging. Occasionally, chronic subdural hematomas can develop following CSF diversion for hydrocephalus, especially if the ventricles were large before CSF diversion or if there is a brain/calvarial vault disproportion (Figs 10A, B). Even if a hematoma is fairly large, action is not needed if the patient has no symptoms. However, if the collection continues to increase in size and/or the patient is symptomatic, treatment consists of burr hole drainage and possible placement of a subdural peritoneal shunt. 5. Conclusion Most neurosurgical complications encountered in the rehabilitation setting involve problems with CSF
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circulation. Modern imaging techniques have greatly aided the diagnosis and treatment of impaired CSF drainage. The direct effects of increased resistance to CSF absorption are raised intracranial pressure affecting neurological function and producing unwanted CSF collections that impair wound healing or lead to wound breakdown. Shunt malfunction and/or infection is a potential problem that may be obvious or very difficult to diagnose. CSF infection is more common if a shunt is present and is best diagnosed by CSF cultures, as other indices are much less reliable. Other locations of central nervous system infection are much less frequent. Acute hemorrhage is a rare complication; more commonly encountered is bleeding associated with a chronic subdural hematoma.
[5]
[6]
[7]
[8]
[9]
[10]
Conflict of interest The authors have no conflict of interest to declare.
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