Postoperative swallowing function after posterior fossa tumor resection in pediatric patients

Transcription

1 Childs Nerv Syst (2006) 22: DOI /s z ORIGINAL PAPER Lisa A. Newman Frederick A. Boop Robert A. Sanford Jerome W. Thompson Carrie K. Temple Christopher D. Duntsch Postoperative swallowing function after posterior fossa tumor resection in pediatric patients Received: 1 August 2005 Published online: 8 June 2006 # Springer-Verlag 2006 L. A. Newman. J. W. Thompson Department of Otolaryngology, Head & Neck Surgery, Science Center, Memphis, TN USA F. A. Boop. R. A. Sanford. C. D. Duntsch Department of Neurosurgery, Science Center, 847 Monroe Avenue, Suite 427, Memphis, TN 38163, USA C. K. Temple Le Bonheur Children s Medical Center, Memphis, TN, USA F. A. Boop (*). R. A. Sanford Department of Pediatrics, Science Center, Memphis, TN, USA fboop@semmes-murphey.com Tel.: Fax: Present address: L. A. Newman Walter Reed Army Medical Center, Washington, DC, USA Abstract Objective: After tumor resection involving the posterior fossa, postoperative swallowing dysfunction may be anticipated. This retrospective study was designed to document swallowing abnormalities in children after posterior fossa brain tumor surgery and to recommend management approaches for children at risk for aspiration. Methods: Twenty-four children referred postoperatively for a video fluoroscopic swallow study (VFSS) out of 127 children undergoing posterior fossa surgery for brain tumor resection from 1998 to 2001 were evaluated for oral, pharyngeal, and cervical esophageal transits. Conclusion: Less than half of the 24 children swallowed functionally within the first week after surgery. VFSS was an appropriate tool for diagnosing swallowing dysfunction, which is impossible to determine at bedside. Children with brain stem involvement and more difficult recovery had significantly worse swallowing function and greater aspiration. We recommend that children with compromised swallowing function should not feed orally until a radiographic swallowing assessment demonstrates functional and safe swallowing with or without therapeutic intervention. Keywords Posterior fossa. Pediatric brain tumor. Swallow function. Modified barium swallow. Aspiration Introduction Brain tumors are the most common solid tumor and the second most common malignancy of childhood [1]. Posterior fossa brain tumors account for approximately 60 70% of all pediatric brain tumors [2]. These tumors produce neurologic symptoms that vary depending on the size, location, and invasive quality of the tumor [3]. After tumor resection, there may be additional neurologic signs and symptoms, either immediate or delayed, transient or permanent. For example, after resection of a tumor that involves the floor of the fourth ventricle, the lateral aspect of the pons, or the lower cranial nerves, immediate postoperative swallowing dysfunction can be anticipated. Alternatively, a posterior fossa syndrome can develop 1 to 4 days after posterior fossa tumor surgery that includes truncal dystonia, irritability, and mutism. This syndrome may also include dysphagia (the inability to swallow) along with lower cranial nerve palsies [4]. In such cases, swallowing dysfunction may not be present immediately after extubation, but may occur in a delayed fashion.

2 1297 It is important to accurately diagnose swallowing abnormalities after surgery in the posterior fossa to prevent aspiration pneumonia, a major cause of morbidity and mortality in children after such surgery. Early recognition also allows alternative management of nutrition and hydration. Because swallowing function has never been objectively documented postsurgically in this patient population, this retrospective study was designed to document swallowing abnormalities in a cohort of children after posterior fossa brain tumor surgery and to recommend a management approach for children at risk for aspiration. Materials and methods Subjects A cohort of 127 children undergoing posterior fossa surgery for resection of brain tumors from1998 to 2001 was reviewed for this study, including 24 children (19%) referred for video fluoroscopic swallow studies (VFSS), before being allowed to eat orally. There were nine girls and 15 boys ranging in age from 8 months to 17.8 years, with a mean age of 5.9 years (SD=5.3 years). When the neurosurgeon determined the child was medically stable, the patient was evaluated for swallowing using a VFSS. Children considered at risk were those whose tumors arose from the cerebellopontine angle, those arising from the lateral aspect of the pons or medulla, or those whose tumors arose from or invaded the floor of the fourth ventricle. In such cases, the children were kept sedated and intubated overnight after their surgery. A pediatric otolaryngologist was present and evaluated each child s vocal cord movement, pharyngeal motility, and gag reflex before extubation. Those children who had an altered level of consciousness, vocal cord paresis, diminished gag reflex, or poor pharyngeal sensation were either not extubated the day after surgery or were extubated but kept non per os until a formal swallowing evaluation could be undertaken. All children were evaluated at a mean of 6.13 days postoperatively (SD=4.07 days), with a range from 2 to 18 days. Children were not sedated at the time of evaluation and for at least 24 h postextubation. Tumor location and surgeries are listed in Table 1. Swallow evaluation All subjects underwent a video fluoroscopic swallow study of oral, pharyngeal, and cervical esophageal transits. A Table 1 Patient population: age, tumor type, posterior fossa location, and degree of surgical resection Age (years) Tumor type and location Surgery Left CP angle ependymoma Gross total resection Left CP angle ependymoma Gross total resection Recurrent post fossa ependymoma Gross total resection Left CP angle ependymoma Gross total resection Ependymoma Gross total resection Fourth ventricular ependymoma Gross total resection Recurrent dorsally exophytic brain stem tumor Gross total resection Cervicomedullary glioma Near total resection Dorsally exophytic brain stem tumor Two resections Fourth ventricular CP angle ependymoma Gross total resection 11 2 Recurrent fourth ventricular ependymoma Gross total resection Malignant fibrous histiocytoma with brain stem invasion Gross total resection 13 2 Posterior fossa dorsally exophytic glioma Near total resection Dorsally exophytic brain stem tumor Near total resection Anaplastic ependymoma, residual fourth ventricular tumor Gross total resection Dorsal midbrain tumor Near total resection Giant cerebellar astrocytoma Gross total resection JPA Gross total resection JPA with brain stem involvement Gross total resection Fourth ventricular ependymoma Gross total resection CP angle medullomyoblastoma Gross total resection CP angle ependymoma Gross total resection CP angle ependymoma Gross total resection Posterior fossa medulloblastoma Gross total resection CP Cerebellopontine, JPA juvenile pilocystic astrocytoma

3 1298 General Electric (Milwaukee, WI, USA) SFX2 table unit fluoroscope was used, and the study was recorded on a Panasonic (Division of Matsushita Electric Corporation of America, Secaucus, NJ) AG-MD830 videocassette recorder. A Fora Video Timer (Japan) was interfaced with the videocassette recorder, which superimposed timing information (hours, minutes, seconds, and hundredths of seconds) on the videotape image. The subjects were seated approximately upright in a seat and viewed in the lateral projection. A 40% w/w (60% w/v) EZ-EM premixed liquid barium suspension was administered to each child in the following volumes (two trials per volume): 1, 3, and 5 ml. Three-milliliter volumes of pudding barium (2 parts Hunts Snack Pack pudding mixed with 1 part EZ-EM Paste) and a cookie covered with barium pudding were also administered. The number of swallows the children were able to complete depended on the severity of the swallow and the tolerance of the child. The study was stopped if there was severe aspiration, which would endanger the child, or if the child was unable to continue. The infants received their barium in a bottle through a Similac Infant Nipple & Ring (Columbus, OH, USA). The hole in the nipple was enlarged to 3 mm with a scalpel, allowing the slightly thicker barium suspension to flow through the nipple. The parents or the clinician fed the children. Overall, maximum radiation exposure was limited to 1 to 2 min. The videotape was analyzed using a Panasonic AG-MD- 830 videocassette recorder and JVC 13-in. monitor, which allowed for slow motion and frame-by-frame analysis. Such an analysis allowed for the evaluation of variables that are not easily visualized in real time. Each liquid swallow was analyzed for the following variables: 1. Oral transit anomalies Loss of material to the floor of the mouth, anterior sulcus, or lateral sulcus; inability to form a bolus; abnormal tongue movements; incomplete tongue to palate contact; nasopharyngeal backflow during the oral phase; material falling over the base of the tongue before initiation of the swallow; and oral residue 2. Oral transit time Time (seconds) from the onset of the oral bolus propulsion to the bolus head reaching the rami of the mandible [5] 3. Pharyngeal transit anomalies Delayed onset or absence of the pharyngeal response; reduced hyoid/ laryngeal movement; nasopharyngeal backflow; abnormal base of tongue to the posterior pharyngeal wall contact from Mid C2 to Superior C3; laryngeal penetration; aspiration; and pharyngeal residue 4. Pharyngeal transit time Time (seconds) from when the bolus head reaches the rami of the mandible to cricopharyngeal closure 5. Laryngeal penetration Defined by material entering the laryngeal vestibule or entrance of the airway to any extent down to the level of the true vocal folds [5] 6. Aspiration Defined by entry of material below the true vocal folds [5] 7. Percent aspiration 8. Nasopharyngeal backflow Defined by material posterior or superior to the soft palate 9. Cough in the presence of aspiration 10. Ability to clear airway (penetration/aspiration) of barium after laryngeal penetration or aspiration Up to five swallows per videotape (some patients had fewer than five swallows altogether) were analyzed by another clinician at a separate time and compared to determine interexaminer reliability of oral and pharyngeal transit times, oral and pharyngeal anomalies, laryngeal penetration, aspiration, nasopharyngeal backflow, cough, and ability to clear the airway. Eighty-two swallows were analyzed by a second clinician with excellent interrater reliability: 91% agreement for oral transit time, 99% for oral transit anomalies, 95% for pharyngeal transit time, and 100% for the other variables. Statistical analyses included measures of central tendency, Student s t test to compare groups using parametric data, and chi-square to compare groups using nonparametric data. SAS-JMP software was used for statistical analysis. A P value of 0.05 was considered statistically significant. Results There was a range of 1 18 swallows analyzed per child (mean=5.83, SD=4.83). Twenty (83%) of 24 children had oral transit anomalies, two so severe they were unable to move material into the pharynx. Of the 22 children in whom pharyngeal transit was observed, 11 (50%) had pharyngeal transit anomalies. Six (27%) of the children experienced laryngeal penetration, five (23%) aspirated, and six (27%) had nasopharyngeal backflow. Of the five children who aspirated, only two of the children coughed and only one of the two cleared the airway. Figure 1 displays a child aspirating barium during a swallow study demonstrating barium in both the esophagus and trachea. Of the 22 children for whom pharyngeal transit was observed, the five children who aspirated were initially evaluated later in their postoperative course, had fewer swallows during their study, had a significantly greater percentage of oral transit and pharyngeal transit anomalies, had significantly longer pharyngeal transit times and greater pharyngeal residue than children who did not aspirate (Table 2). In addition, children with brain stem involvement had on average a greater volume of the entire bolus aspirated (t= 4.25, P=0.05). There was a significant relationship between age and the degree of aspiration, with older children demonstrating greater aspiration (r 2 =0.89, F=24.32, P=0.01). Nineteen (79%) of the 24 children had a gross total resection of their tumor and five (21%) had a near total resection. There were no significant differences

4 1299 Fig. 1 X-ray micrograph demonstrating a child aspirating barium into the trachea during a swallow study in any swallowing parameters between those who had a gross total resection and those who did not. In summary, most of the children in this at-risk cohort demonstrated some swallowing abnormalities after posterior fossa tumor resection. Two children had such severe oral transit difficulties that pharyngeal transit could not be observed. Half of the remaining 22 children had pharyngeal transit abnormalities. Thus, the other 11 children had adequate functional oral pharyngeal transits within the first week after surgery. Seven out of 24 children (29%) had swallowing difficulties, as demonstrated on the modified barium swallow, which were significant enough to warrant a feeding tube, usually a nasogastric tube. Only one child needed a gastronomy tube. Discussion and conclusions Although most experienced neurosurgical units are attuned to the clinical clues of a child at risk for aspiration, such as a child with altered sensorium, one who is hoarse after extubation, a drooling child, or a child who coughs frequently, many in this cohort were at risk without overt signs. Of the five children who aspirated, only one coughed and cleared his airway. Thus, it would be impossible to determine from the bedside whether the children were silently aspirating and/or at risk for pulmonary complications. This emphasizes the need for a formal assessment of swallowing to determine when the child can begin oral feedings postoperatively. Understandably, children with brain stem or lower cranial nerve involvement from their tumor had more aspiration than those without brain stem involvement. Brain stem involvement affects the neural control of swallowing, which appears to be at the level of the medulla in the nucleus of the tractus solitarius and adjacent reticular formation and the nucleus ambiguous [6, 7]. Children with swallowing problems related to lower cranial nerve manipulation can generally be expected to recover function over time. Alternatively, children with nuclear involvement of the brain stem may take longer to recover or may never recover protective reflexes. Alternate methods of feeding (e.g., nasogastric tubes or hyperalimentation) would be an excellent way to manage nutrition and hydration during the early postoperative recovery period. When recovery of swallowing function is delayed beyond 2 weeks or if the child demonstrates frank aspiration, early tracheostomy and percutaneous gastrostomy can be lifesaving. Gastroesophageal reflux in the presence of swallowing dysmotility can also lead to aspiration. Adding color to tube feedings with the addition of methylene blue dye is an inexpensive and reliable means of diagnosing reflux aspiration if suctioning the aspirate reveals blue-tinged sputum. In such instances, children may be best protected from aspiration by the addition of a Nissen fundoplication to their gastrostomy. Recovery of swallowing function must still be documented by fluoroscopy at a later date before resuming oral feeding. In summary, less than half of the 24 children referred for video fluoroscopy in this study were able to swallow functionally within the first week after surgery. The video fluoroscopic swallow study was an appropriate tool for diagnosing the swallowing disorder, which would be impossible to determine at bedside. Children with brain stem involvement and more difficult postoperative recovery had significantly worse swallowing function and were more likely to be at risk for aspiration. When the neurosurgical resection of posterior fossa tumors involves Table 2 Comparison of swallowing parameters among children with and without aspiration Children with aspiration, n=5 Children without aspiration, n=17 P value Mean days examined with fluoroscopy postoperatively * Mean percentage of swallows with oral anomalies * Mean oral transit time (seconds) Mean percentage of pharyngeal transit anomalies * Mean pharyngeal transit time (seconds) * Mean percentage residue * *P 0.05

5 1300 the lateral aspect of the brain stem, the floor of the fourth ventricle, or the lower cranial nerves, the neurosurgeon should consider the child at risk for swallowing dysmotility. Furthermore, children with altered levels of consciousness or those who develop a posterior fossa syndrome may also demonstrate swallowing dysfunction or poor airway protection. In such cases, the authors recommend keeping the children intubated overnight after surgery and having the child s vocal cord function, pharyngeal sensation, and airway protection assessed by endoscopy at the time of extubation. For those children with abnormalities, we recommend no oral feeding until a formal instrumental swallowing assessment can demonstrate functional and safe swallowing with or without therapeutic intervention. When swallowing deficits are present, repeat VFSS should be performed when changes in medical or physical status might indicate an improvement in swallowing. References 1. Hudgins RJ, Edwards MSB (1987) Management of infratentorial brain tumors. Pediatr Neurosci 13: Jean A, Car A (1979) Inputs to the swallowing medullary neurons from the periphery afferent fibers and the swallowing cortical area. Brain Res 178: Kirk EA, Howard VC, Scott CA (1995) Description of posterior fossa syndrome in children after posterior fossa brain tumor surgery. J Pediatr Oncol Nurs 12: Logemann JA, Shanahan T, Rademaker AW, Kahrilas PJ, Lazar R, Halper A (1993) Oropharyngeal swallowing after stroke in the left basal ganglion/internal capsule. Dysphagia 8: Miller A (1986) Neurophysiological basis of swallowing. Dysphagia 1: Mukand JA, Blackinton DD, Crincoli MG, Lee JJ, Satos BB (2001) Incidence of neurologic deficits and rehabilitation of patients with brain tumors. Am J Phys Med Rehabil 80: Shiminski-Maher T (1996) Brainstem tumors in childhood: preparing patients and families for long- and short-term care. Pediatr Neurosurg 24: