Student Paper Communication étudiante Ventriculoperitoneal shunt for treatment of hydrocephalus in a French bulldog puppy Jolene A. Giacinti Abstract — A 6.5-week-old bulldog was presented with lethargy, anorexia, and stunted growth. A domed skull, ventrolateral strabismus, hypermetria, and delayed hopping were observed. Congenital hydrocephalus was diagnosed and a ventriculoperitoneal shunt was placed. After surgery, a shunt obstruction occurred but resolved with treatment. The puppy responded well and neurological deficits continued to improve after surgery. Résumé — Dérivation ventriculo-péritonéale pour le traitement de l’hydrocéphalie chez un chiot Bouledogue français. Un Bouledogue âgé de 6,5 semaines a été présenté pour de l’abattement, de l’anorexie et une croissance retardée. Un crâne en forme de dôme, du strabisme ventrolatéral, de l’hypermétrie et du sautillement retardé ont été observés. Une hydrocéphalie congénitale a été diagnostiquée et une dérivation ventriculo-péritonéale a été placée. Après la chirurgie, une obstruction de la dérivation s’est produite mais s’est résorbée après un traitement. Le chiot a bien répondu et les déficits neurologiques ont continué de s’améliorer après la chirurgie. Can Vet J 2016;57:309–312
A
6.5-week-old female French bulldog puppy was presented to Quakertown Veterinary Clinic, Quakertown, Pennsylvania, for lethargy, recent anorexia, and failure to grow appropriately. On presentation, the patient had a markedly domed skull (Figure 1), bulging star-shaped fontanelle, overall small stature, and a foreshortened rib cage with mild pectus excavatum. Neurologic examination detected depressed demeanor, marked ventrolateral strabismus, hypermetria, and delayed hopping in the hind limbs. The patient had a normal temperature, pulse, respiration, packed cell volume, and total protein. On auscultation a I/VI systolic heart murmur was noted at the left heart base. Ultrasound via the open fontanelle showed dilation of the left and right ventricles with a narrow strip of cortical brain visible that widened only over the intraventricular septum. Based on clinical features, a diagnosis of congenital hydrocephalus was made. Immediate treatment included ultrasound-guided aseptic ventriculocentesis via a 25-gauge needle in the left side of the fontanelle to reduce cerebrospinal fluid (CSF) pressure. Approximately 0.2 mL of clear CSF was collected by passive flow with no sedation needed. The bulge on the right side of
Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G 2W1. Address all correspondence to Jolene Giacinti; e-mail: [email protected] Ms. Giacinti will receive 50 copies of her article free of charge, courtesy of The Canadian Veterinary Journal. Use of this article is limited to a single copy for personal study. Anyone interested in obtaining reprints should contact the CVMA office ([email protected]) for additional copies or permission to use this material elsewhere. CVJ / VOL 57 / MARCH 2016
(Traduit par Isabelle Vallières)
the fontanelle remained after centesis so the procedure was repeated on the right side. Another 0.2 mL of clear CSF was gently aspirated from the right side using a tuberculin syringe, reducing the height of the bulging right fontanelle. Immediate improvement of strabismus and activity was noted. The eyes returned to a normal position and the puppy followed a gauze square moved before her. Neomycin, polymyxin B, bacitracin ointment (BNP; Bausch and Lomb, Rochester, New York, USA) was applied to the centesis sites and the puppy was returned to her owners. The owners immediately noted the change in the puppy’s activity and attitude. After further discussion and consideration the client elected surgical placement of a Delta medium pressure passive ventriculoperitoneal (VP) shunt (Medtronics, Philadelphia, Pennsylvania, USA). Placement of the VP shunt was performed 14 d after initial presentation when the patient was 8.5 wk old. A pre-surgical transfontanellar ultrasonographic examination was used as a guide for the ventricular catheter placement site, and the depth of insertion and length adjustment of the intraventricular catheter. Accumulation of CSF, a visible ventricular septum along the midline, and a ventricular depth of 3 cm were noted on ultrasound examination. An IV catheter was placed and the patient was administered sodium chloride (0.9% NaCl; Abbott, Chicago, Illinois, USA), 1 mL/kg body weight (BW) per hour, to meet maintenance requirements. Buprenorphine (0.5 mg/mL; Stokes Healthcare Compounding Pharmacy, Putney, Pennsylvania, USA), 0.08 mL, IV, was administered before surgery. The patient was induced with propofol (10 mg/mL, Teva, Petah Tikva, Israel), 1.4 mL, and maintained on isoflurane (VetOne, Boise, Idaho, USA) and oxygen via tracheal intubation. The patient was placed in sternal recumbency and the left side was clipped from poll to tail and aseptically prepared. 309
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Figure 2. Post-operative radiograph to confirm placement of ventriculoperitoneal shunt.
Figure 1. Markedly domed skull present in a 6.5-week-old bulldog diagnosed with congenital hydrocephalus.
A stab incision was made on the left flank 2 to 3 cm caudal to the last rib, halfway between the lumbar spine and ventral abdomen. A 2.5-mm diameter barium-impregnated distal shunt catheter (Medtronics) was placed subcutaneously, then tunneled to the base of the neck and anchored with a mosquito hemostat. A curved incision was made along the caudal aspect of the parietal bone of the skull from the midline, 2 to 3 cm laterally curving along the medial base of the pinna. The skin flap was undermined with a mosquito hemostat and flapped forward over the brow and weighted with a towel clamp. The Delta shunt attachment site was chosen along the back of the skull and measurement made for the appropriate trim length of the intraventricular catheter with the shunt valve directional arrow oriented toward the tail. A winged right angle catheter anchor was selected and the intraventricular shunt was seated into the clip to maintain a 90-degree bend. The paired unit was attached to the rostral male attachment site of the Delta shunt. A small hole was created in the parietal bone and dura with the bevel of an 18-gauge needle just large enough to allow introduction of the intraventricular catheter. The 2.5-mm diameter bariumimpregnated ventricular shunt catheter with fenestrated tip was placed to the premeasured depth of 2.5 cm in the left ventricle. The winged catheter anchor was sutured to the periosteum of the skull with 4.0 polydioxanone (PDS I; Ethicon, Somerville, New Jersey, USA). The Medtronics medium pressure Delta fixed valve was attached to the distal catheter that was tunneled to the base of the neck. Once CSF was confirmed to be flowing the 310
attachments were secured with 4-0 poliglecaprone 25 (monocryl; Ethicon). The abdominal portion of the catheter was inserted using a muscle separation technique and the peritoneum was incised. One-third the full length of the distal shunt catheter was placed intra-abdominally. The distal tubing remained floating in the subcutaneous tunnel on her flank to the abdominal entrance. At the point of catheter entry into the abdomen, the muscles were tacked together to make a close but non-trapping stoma. The subcutaneous layers were closed in a continuous pattern with 4-0 poliglecaprone 25 and the skin incisions were closed with a combination of cruciate and simple interrupted patterns with 4-0 nylon (ethilon; Ethicon). Post-operative radiographs were taken to confirm shunt placement (Figure 2). Recovery was smooth and uneventful. Ampicillin (250 mg diluted to 100 mg/mL; Sagent Pharmaceuticals, Schaumburg, Illinois, USA), 0.3 mL, IV, was administered after surgery and repeated 8 h later. Buprenorphine (0.5 mg/mL; Stokes Healthcare Compounding Pharmacy) 0.08 mL, IV, and meloxicam (5 mg/mL; Metacam, Boehringer Ingelheim, Ridgefield, Connecticut, USA), 0.04 mL, IV, were administered 6 h after surgery. Temperature and blood glucose were monitored overnight. The patient was discharged the next morning with amoxicillin (50 mg/mL, Amoxidrops; Pfizer, New York, New York, USA), 1 drop, PO, q12h for 14 d and meloxicam (Boehringer Ingelheim), 0.04 mL q24h for 3 to 5 d and a soft Elizabethan collar and instructions for strict rest while the incision was healing. The patient was reported to be eating well at home with an appropriate energy level 3 d after surgery. The incision was healing satisfactorily and the sutures were removed at a recheck appointment 7 d later. Seventeen days after surgery the patient was presented with a sudden change in behavior, anorexia, and lethargy. She was reluctant to walk and sat with her head down. On physical examination the puppy had a slight right head tilt, mild anisocoria, and the fontanelle was slightly domed. The shunt and tubing appeared to be seated normally. Blood glucose was within normal limits. A complete blood (cell) count (CBC) was performed to identify infection secondary to shunt placement; the results were within normal limits with the exception of mild thrombocytosis. Although central nervous system infection could not be excluded based on a normal white blood cell CVJ / VOL 57 / MARCH 2016
Discussion Congenital hydrocephalus typically presents within the first few months of life. An enlarged, dome-shaped head with persistent fontanelles and open cranial sutures is a common finding. Patients are typically smaller than average, fail to thrive, and have obtunded mentation. Ventral or ventrolateral strabismus is common in addition to a range of other visual deficits up to and including blindness with an absent menace response. Gait abnormalities and seizure activity are also reported. Clinical features are the result of ventricular distension and increased intracranial pressure, which cause compression of the brain parenchyma, predominantly the white matter (1,2). Re-expansion and regeneration of axons can occur if the pressure is alleviated in a timely fashion; however, neuronal loss is irreversible so it is imperative to treat early and aggressively (3,4). CVJ / VOL 57 / MARCH 2016
Medical therapy can be used for temporary treatment; diuretics and glucocorticoids decrease CSF production and therefore can be used to delay surgery or when surgery is not an option. Surgical ventricular shunt placement is considered the best course of treatment and is required when clinical signs do not respond to medical therapy in order to prevent permanent neurologic damage. Systemic or dermatologic infections are contraindications to the placement of a shunt (5,6). Ventricular shunts move CSF from the ventricles into another body cavity such as the right atrium or the abdominal cavity. Ventriculoperitoneal shunts are most commonly used in veterinary medicine. Shunts are typically made of a silicone elastomer and are impregnated with barium for radiopacity. These shunts are equipped with a one-way valve that responds to a pressure differential between the ventricles and the space into which the distal catheter is draining. Low-, medium-, and high-pressure valves are available but newer models are adjustable and some include reservoirs for easy CSF sampling (5,6). In humans, excessive drainage of CSF can result from a siphon effect created by rapid, gravity-induced changes in pressure differentials between supine, sitting, and standing positions (7). Over shunting has serious consequences as it can lead to the collapse of the expanded ventricles and subsequent tearing of vessels resulting in subdural hematomas (7). In the quadruped, siphoning and subsequent over-drainage is less of a risk because the shunt sits in a more horizontal orientation with the head at roughly the same level as the abdomen (6,8). A medium pressure valve (0.69 kPa) was selected for the bulldog puppy in consultation with Medtronics and a neurologist, because it most closely approximates the normal canine ventricular pressures (between 0.67 and 1.60 kPa) (9). Careful monitoring is important because over-drainage remains a possibility, particularly in animals with largely dilated lateral ventricles and only a thin rim of cerebral cortex present on imaging (6). In dogs and cats, VP shunt complication rates range from 25% to 29% with most occurring within the first 3 mo (10,11). Shunt obstruction is the most common complication of VP shunt placement (3,5). Obstruction can be caused by blood clots, debris, proliferative glial tissue, choroid plexus, or abdominal adhesions, all of which can lead to failure of CSF flow (3,5). These patients typically improve after shunt placement and then acutely present with abnormal behavior, lethargy, or ataxia (3,5). The cause of obstruction was not definitively diagnosed in the bulldog puppy; however, suspected causes include protein debris, clots, or fibrin blockage and expansion of cortex post shunting and/or reactive astrocytosis causing blockage of the intraventricular catheter. As fenestrations are present circumferentially, blockage due to expanded cortex was not likely to have compromised the function of the intraventricular portion of the shunt in this case. Furthermore, obstruction due to cortical expansion is unlikely to resolve without surgical shunt revision and the puppy showed clinical improvement with medical therapy alone. In the present case, clot or fibrin obstruction was the working diagnosis, which resolved with time and steroid administration. Infection of the shunt is another possible complication but has been reported to occur less commonly in dogs and cats 311
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count on CBC, shunt obstruction was the primary differential. Ventriculocentesis was performed to stabilize CSF pressures; the CSF was clear, providing further evidence for obstruction versus infection. The patient was admitted and scheduled for surgical shunt revision. The case was reviewed with a neurologist and a radiologist. Ultrasound examination showed the position of the intraventricular catheter with an expanded cortical brain width resting against the catheter. The patient was started on prednisolone (15 mg/5 mL; Pred Syrup, HiTech, Norcross, Georgia, USA), 3 mL, PO, q24h, and amoxicillin (50 mg/mL; Amoxidrops, Pfizer), 1 drop, PO, q12h to address underlying inflammatory and infectious causes in addition to subcutaneous sodium chloride fluids, buprenorphine (0.5 mg/mL; Stokes Healthcare Compounding Pharmacy), 0.08 mL, IM, and omeprazole (20 mg; Prilosec, Dorneyville Pharmacy, Allentown, Pennsylvania, USA), 1/10th of a tablet q24h. Repeated digital palpation of the fontanelle was used to assess the volume of CSF present. Ventriculocentesis was performed as needed to maintain a level fontanelle and normal mentation until a replacement was available. The patient was in hospital for 7 d during which the shunt gradually regained functionality and a marked improvement in the puppy was noted; CSF pressures normalized, the right head tilt was reduced, anisocoria resolved, and behavior and appetite returned to normal. A shunt revision was no longer deemed necessary and the patient was discharged with prednisolone (15 mg/5 mL, Pred Syrup; HiTech), 3 mL, q24h for 3 d, then every other day for 5 d, amoxicillin (50 mg/mL, Amoxidrops; Pfizer), 1 drop, q12h for 14 d and omeprazole (20 mg, Prilosec; Dorneyville Pharmacy), 1/10th of a tablet q24h. At 14.5, 18, and 24 wk of age the patient was presented for DHPP (distemper, hepatitis, parvovirus, parainfluenza) vaccination series. She remained small in stature but her body condition was normal and she was reported to be doing well at home. The shunt continued to be seated correctly. On neurologic examination the puppy was bright and alert, eyes were positioned normally, pupillary light reflexes were delayed, hypermetria and delayed hopping in the hind limbs were present but markedly improved from initial presentation. At present the patient is 30 wk of age and continues to do well.
C O M M U N I CAT I O N É T U D I A N T E
c ompared with humans (3,5). Prophylactic use of antimicrobials is a consideration for future VP shunt placements as perioperative contamination is the most likely route of bacterial introduction and cause of post-surgical infection (12,13). Reported postoperative clinical improvement rates after shunt placement range from 72% to 100% (10,11,14). In a retrospective study performed by Biel et al (10), 72% of animals with congenital hydrocephalus had clinical improvement after shunt placement and 25% had resolution of clinical signs. Postoperative survival was 80% at 1 mo, 66% at 3 mo, and 55% at 18 mo (10). Follow-up data were available for 1 animal 9.5 y later (10). Shihab et al (14) reported neurologic improvement in 100% of 12 dogs after shunt placement. Continued improvement was seen in 9 dogs, 1 of which required revision surgery due to shunt obstruction. In summary, a VP shunt was placed in a bulldog puppy with congenital hydrocephalus to relieve intracranial pressure and treat the underlying blockage of CSF flow. The dog responded well to shunt placement despite initial complications and neurological status continued to improve at 30 wk. In this case VP shunt placement was a viable option for treatment of a puppy with congenital hydrocephalus; the procedure prolonged survival time and improved quality of life.
Acknowledgments The author thanks Dr. Rosemary Newton for her expertise and guidance with this case and the veterinarians and staff at Quakertown Veterinary Clinic for hosting my externship. CVJ
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References 1. Rekate HL. A contemporary definition and classification of hydrocephalus. Semin Pediat Neurol 2009;16:9–15. 2. Wünschmann A, Oglesbee M. Periventricular changes associated with spontaneous canine hydrocephalus. Vet Pathol 2001;38:67–73. 3. Dewey C, Coates J, Axlund T, Smith J. Hydrocephalus in dogs and cats. Compend Contin Educ Pract Vet 2006;28:136–146. 4. Yamada H, Yokota A, Furuta A, Horie A. Reconstitution of shunted mantle in experimental hydrocephalus. J Neurosurg 1992;76:856–862. 5. Thomas WB. Hydrocephalus in dogs and cats. Vet Clin North Am Small Anim Pract 2010;40:143–159. 6. Harrington ML, Bagley RS, Moore MP. Hydrocephalus. Vet Clin North Am Small Anim Pract 1996;26:843–856. 7. Pudenz R, Foltz E. Hydrocephalus: Overdrainage by ventricular shunts. A review and recommendations. Surg Neurol 1991;35:200–212. 8. Yamada S, Ducker T, Perot P. Dynamic changes of cerebrospinal fluid in upright and recumbent shunted experimental animals. Childs Brain 1975;1:187–192. 9. Dewey C. Head trauma management. In: A Practical Guide to Canine and Feline Neurology. 2nd ed. Ames, Iowa: Wiley-Blackwell, 2008:223. 10. Biel M, Kramer M, Forterre F, et al. Outcome of ventriculoperitoneal shunt implantation for treatment of congenital internal hydrocephalus in dogs and cats: 36 cases (2001–2009). J Am Vet Med Assoc 2013;242:948–958. 11. de Stefani A, de Risio L, Platt SR, Matiasek L, Lujan-Pascual A, Garosi LS. Surgical technique, postoperative complications and outcome in 14 dogs treated for hydrocephalus by ventriculoperitoneal shunting. Vet Surg 2011;40:183–191. 12. Ratilal B, Costa J, Sampaio C. Antibiotic prophylaxis for surgical introduction of intracranial ventricular shunts: A systematic review. J Neurosurg Pediatr 2008;1:48–56. 13. Langley J, LeBlanc J, Drake J, Milner R. Efficacy of antimicrobial prophylaxis in placement of cerebrospinal fluid shunts: Meta-analysis. Clin Infect Dis 1993;17:98–103. 14. Shihab N, Davies E, Kenny PJ, Loderstedt S, Volk HA. Treatment of hydrocephalus with ventriculoperitoneal shunting in twelve dogs. Vet Surg 2011;40:477–484.
CVJ / VOL 57 / MARCH 2016
A
6.5-week-old female French bulldog puppy was presented to Quakertown Veterinary Clinic, Quakertown, Pennsylvania, for lethargy, recent anorexia, and failure to grow appropriately. On presentation, the patient had a markedly domed skull (Figure 1), bulging star-shaped fontanelle, overall small stature, and a foreshortened rib cage with mild pectus excavatum. Neurologic examination detected depressed demeanor, marked ventrolateral strabismus, hypermetria, and delayed hopping in the hind limbs. The patient had a normal temperature, pulse, respiration, packed cell volume, and total protein. On auscultation a I/VI systolic heart murmur was noted at the left heart base. Ultrasound via the open fontanelle showed dilation of the left and right ventricles with a narrow strip of cortical brain visible that widened only over the intraventricular septum. Based on clinical features, a diagnosis of congenital hydrocephalus was made. Immediate treatment included ultrasound-guided aseptic ventriculocentesis via a 25-gauge needle in the left side of the fontanelle to reduce cerebrospinal fluid (CSF) pressure. Approximately 0.2 mL of clear CSF was collected by passive flow with no sedation needed. The bulge on the right side of
Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G 2W1. Address all correspondence to Jolene Giacinti; e-mail: [email protected] Ms. Giacinti will receive 50 copies of her article free of charge, courtesy of The Canadian Veterinary Journal. Use of this article is limited to a single copy for personal study. Anyone interested in obtaining reprints should contact the CVMA office ([email protected]) for additional copies or permission to use this material elsewhere. CVJ / VOL 57 / MARCH 2016
(Traduit par Isabelle Vallières)
the fontanelle remained after centesis so the procedure was repeated on the right side. Another 0.2 mL of clear CSF was gently aspirated from the right side using a tuberculin syringe, reducing the height of the bulging right fontanelle. Immediate improvement of strabismus and activity was noted. The eyes returned to a normal position and the puppy followed a gauze square moved before her. Neomycin, polymyxin B, bacitracin ointment (BNP; Bausch and Lomb, Rochester, New York, USA) was applied to the centesis sites and the puppy was returned to her owners. The owners immediately noted the change in the puppy’s activity and attitude. After further discussion and consideration the client elected surgical placement of a Delta medium pressure passive ventriculoperitoneal (VP) shunt (Medtronics, Philadelphia, Pennsylvania, USA). Placement of the VP shunt was performed 14 d after initial presentation when the patient was 8.5 wk old. A pre-surgical transfontanellar ultrasonographic examination was used as a guide for the ventricular catheter placement site, and the depth of insertion and length adjustment of the intraventricular catheter. Accumulation of CSF, a visible ventricular septum along the midline, and a ventricular depth of 3 cm were noted on ultrasound examination. An IV catheter was placed and the patient was administered sodium chloride (0.9% NaCl; Abbott, Chicago, Illinois, USA), 1 mL/kg body weight (BW) per hour, to meet maintenance requirements. Buprenorphine (0.5 mg/mL; Stokes Healthcare Compounding Pharmacy, Putney, Pennsylvania, USA), 0.08 mL, IV, was administered before surgery. The patient was induced with propofol (10 mg/mL, Teva, Petah Tikva, Israel), 1.4 mL, and maintained on isoflurane (VetOne, Boise, Idaho, USA) and oxygen via tracheal intubation. The patient was placed in sternal recumbency and the left side was clipped from poll to tail and aseptically prepared. 309
C O M M U N I CAT I O N É T U D I A N T E
Figure 2. Post-operative radiograph to confirm placement of ventriculoperitoneal shunt.
Figure 1. Markedly domed skull present in a 6.5-week-old bulldog diagnosed with congenital hydrocephalus.
A stab incision was made on the left flank 2 to 3 cm caudal to the last rib, halfway between the lumbar spine and ventral abdomen. A 2.5-mm diameter barium-impregnated distal shunt catheter (Medtronics) was placed subcutaneously, then tunneled to the base of the neck and anchored with a mosquito hemostat. A curved incision was made along the caudal aspect of the parietal bone of the skull from the midline, 2 to 3 cm laterally curving along the medial base of the pinna. The skin flap was undermined with a mosquito hemostat and flapped forward over the brow and weighted with a towel clamp. The Delta shunt attachment site was chosen along the back of the skull and measurement made for the appropriate trim length of the intraventricular catheter with the shunt valve directional arrow oriented toward the tail. A winged right angle catheter anchor was selected and the intraventricular shunt was seated into the clip to maintain a 90-degree bend. The paired unit was attached to the rostral male attachment site of the Delta shunt. A small hole was created in the parietal bone and dura with the bevel of an 18-gauge needle just large enough to allow introduction of the intraventricular catheter. The 2.5-mm diameter bariumimpregnated ventricular shunt catheter with fenestrated tip was placed to the premeasured depth of 2.5 cm in the left ventricle. The winged catheter anchor was sutured to the periosteum of the skull with 4.0 polydioxanone (PDS I; Ethicon, Somerville, New Jersey, USA). The Medtronics medium pressure Delta fixed valve was attached to the distal catheter that was tunneled to the base of the neck. Once CSF was confirmed to be flowing the 310
attachments were secured with 4-0 poliglecaprone 25 (monocryl; Ethicon). The abdominal portion of the catheter was inserted using a muscle separation technique and the peritoneum was incised. One-third the full length of the distal shunt catheter was placed intra-abdominally. The distal tubing remained floating in the subcutaneous tunnel on her flank to the abdominal entrance. At the point of catheter entry into the abdomen, the muscles were tacked together to make a close but non-trapping stoma. The subcutaneous layers were closed in a continuous pattern with 4-0 poliglecaprone 25 and the skin incisions were closed with a combination of cruciate and simple interrupted patterns with 4-0 nylon (ethilon; Ethicon). Post-operative radiographs were taken to confirm shunt placement (Figure 2). Recovery was smooth and uneventful. Ampicillin (250 mg diluted to 100 mg/mL; Sagent Pharmaceuticals, Schaumburg, Illinois, USA), 0.3 mL, IV, was administered after surgery and repeated 8 h later. Buprenorphine (0.5 mg/mL; Stokes Healthcare Compounding Pharmacy) 0.08 mL, IV, and meloxicam (5 mg/mL; Metacam, Boehringer Ingelheim, Ridgefield, Connecticut, USA), 0.04 mL, IV, were administered 6 h after surgery. Temperature and blood glucose were monitored overnight. The patient was discharged the next morning with amoxicillin (50 mg/mL, Amoxidrops; Pfizer, New York, New York, USA), 1 drop, PO, q12h for 14 d and meloxicam (Boehringer Ingelheim), 0.04 mL q24h for 3 to 5 d and a soft Elizabethan collar and instructions for strict rest while the incision was healing. The patient was reported to be eating well at home with an appropriate energy level 3 d after surgery. The incision was healing satisfactorily and the sutures were removed at a recheck appointment 7 d later. Seventeen days after surgery the patient was presented with a sudden change in behavior, anorexia, and lethargy. She was reluctant to walk and sat with her head down. On physical examination the puppy had a slight right head tilt, mild anisocoria, and the fontanelle was slightly domed. The shunt and tubing appeared to be seated normally. Blood glucose was within normal limits. A complete blood (cell) count (CBC) was performed to identify infection secondary to shunt placement; the results were within normal limits with the exception of mild thrombocytosis. Although central nervous system infection could not be excluded based on a normal white blood cell CVJ / VOL 57 / MARCH 2016
Discussion Congenital hydrocephalus typically presents within the first few months of life. An enlarged, dome-shaped head with persistent fontanelles and open cranial sutures is a common finding. Patients are typically smaller than average, fail to thrive, and have obtunded mentation. Ventral or ventrolateral strabismus is common in addition to a range of other visual deficits up to and including blindness with an absent menace response. Gait abnormalities and seizure activity are also reported. Clinical features are the result of ventricular distension and increased intracranial pressure, which cause compression of the brain parenchyma, predominantly the white matter (1,2). Re-expansion and regeneration of axons can occur if the pressure is alleviated in a timely fashion; however, neuronal loss is irreversible so it is imperative to treat early and aggressively (3,4). CVJ / VOL 57 / MARCH 2016
Medical therapy can be used for temporary treatment; diuretics and glucocorticoids decrease CSF production and therefore can be used to delay surgery or when surgery is not an option. Surgical ventricular shunt placement is considered the best course of treatment and is required when clinical signs do not respond to medical therapy in order to prevent permanent neurologic damage. Systemic or dermatologic infections are contraindications to the placement of a shunt (5,6). Ventricular shunts move CSF from the ventricles into another body cavity such as the right atrium or the abdominal cavity. Ventriculoperitoneal shunts are most commonly used in veterinary medicine. Shunts are typically made of a silicone elastomer and are impregnated with barium for radiopacity. These shunts are equipped with a one-way valve that responds to a pressure differential between the ventricles and the space into which the distal catheter is draining. Low-, medium-, and high-pressure valves are available but newer models are adjustable and some include reservoirs for easy CSF sampling (5,6). In humans, excessive drainage of CSF can result from a siphon effect created by rapid, gravity-induced changes in pressure differentials between supine, sitting, and standing positions (7). Over shunting has serious consequences as it can lead to the collapse of the expanded ventricles and subsequent tearing of vessels resulting in subdural hematomas (7). In the quadruped, siphoning and subsequent over-drainage is less of a risk because the shunt sits in a more horizontal orientation with the head at roughly the same level as the abdomen (6,8). A medium pressure valve (0.69 kPa) was selected for the bulldog puppy in consultation with Medtronics and a neurologist, because it most closely approximates the normal canine ventricular pressures (between 0.67 and 1.60 kPa) (9). Careful monitoring is important because over-drainage remains a possibility, particularly in animals with largely dilated lateral ventricles and only a thin rim of cerebral cortex present on imaging (6). In dogs and cats, VP shunt complication rates range from 25% to 29% with most occurring within the first 3 mo (10,11). Shunt obstruction is the most common complication of VP shunt placement (3,5). Obstruction can be caused by blood clots, debris, proliferative glial tissue, choroid plexus, or abdominal adhesions, all of which can lead to failure of CSF flow (3,5). These patients typically improve after shunt placement and then acutely present with abnormal behavior, lethargy, or ataxia (3,5). The cause of obstruction was not definitively diagnosed in the bulldog puppy; however, suspected causes include protein debris, clots, or fibrin blockage and expansion of cortex post shunting and/or reactive astrocytosis causing blockage of the intraventricular catheter. As fenestrations are present circumferentially, blockage due to expanded cortex was not likely to have compromised the function of the intraventricular portion of the shunt in this case. Furthermore, obstruction due to cortical expansion is unlikely to resolve without surgical shunt revision and the puppy showed clinical improvement with medical therapy alone. In the present case, clot or fibrin obstruction was the working diagnosis, which resolved with time and steroid administration. Infection of the shunt is another possible complication but has been reported to occur less commonly in dogs and cats 311
S T U D E N T PA P E R
count on CBC, shunt obstruction was the primary differential. Ventriculocentesis was performed to stabilize CSF pressures; the CSF was clear, providing further evidence for obstruction versus infection. The patient was admitted and scheduled for surgical shunt revision. The case was reviewed with a neurologist and a radiologist. Ultrasound examination showed the position of the intraventricular catheter with an expanded cortical brain width resting against the catheter. The patient was started on prednisolone (15 mg/5 mL; Pred Syrup, HiTech, Norcross, Georgia, USA), 3 mL, PO, q24h, and amoxicillin (50 mg/mL; Amoxidrops, Pfizer), 1 drop, PO, q12h to address underlying inflammatory and infectious causes in addition to subcutaneous sodium chloride fluids, buprenorphine (0.5 mg/mL; Stokes Healthcare Compounding Pharmacy), 0.08 mL, IM, and omeprazole (20 mg; Prilosec, Dorneyville Pharmacy, Allentown, Pennsylvania, USA), 1/10th of a tablet q24h. Repeated digital palpation of the fontanelle was used to assess the volume of CSF present. Ventriculocentesis was performed as needed to maintain a level fontanelle and normal mentation until a replacement was available. The patient was in hospital for 7 d during which the shunt gradually regained functionality and a marked improvement in the puppy was noted; CSF pressures normalized, the right head tilt was reduced, anisocoria resolved, and behavior and appetite returned to normal. A shunt revision was no longer deemed necessary and the patient was discharged with prednisolone (15 mg/5 mL, Pred Syrup; HiTech), 3 mL, q24h for 3 d, then every other day for 5 d, amoxicillin (50 mg/mL, Amoxidrops; Pfizer), 1 drop, q12h for 14 d and omeprazole (20 mg, Prilosec; Dorneyville Pharmacy), 1/10th of a tablet q24h. At 14.5, 18, and 24 wk of age the patient was presented for DHPP (distemper, hepatitis, parvovirus, parainfluenza) vaccination series. She remained small in stature but her body condition was normal and she was reported to be doing well at home. The shunt continued to be seated correctly. On neurologic examination the puppy was bright and alert, eyes were positioned normally, pupillary light reflexes were delayed, hypermetria and delayed hopping in the hind limbs were present but markedly improved from initial presentation. At present the patient is 30 wk of age and continues to do well.
C O M M U N I CAT I O N É T U D I A N T E
c ompared with humans (3,5). Prophylactic use of antimicrobials is a consideration for future VP shunt placements as perioperative contamination is the most likely route of bacterial introduction and cause of post-surgical infection (12,13). Reported postoperative clinical improvement rates after shunt placement range from 72% to 100% (10,11,14). In a retrospective study performed by Biel et al (10), 72% of animals with congenital hydrocephalus had clinical improvement after shunt placement and 25% had resolution of clinical signs. Postoperative survival was 80% at 1 mo, 66% at 3 mo, and 55% at 18 mo (10). Follow-up data were available for 1 animal 9.5 y later (10). Shihab et al (14) reported neurologic improvement in 100% of 12 dogs after shunt placement. Continued improvement was seen in 9 dogs, 1 of which required revision surgery due to shunt obstruction. In summary, a VP shunt was placed in a bulldog puppy with congenital hydrocephalus to relieve intracranial pressure and treat the underlying blockage of CSF flow. The dog responded well to shunt placement despite initial complications and neurological status continued to improve at 30 wk. In this case VP shunt placement was a viable option for treatment of a puppy with congenital hydrocephalus; the procedure prolonged survival time and improved quality of life.
Acknowledgments The author thanks Dr. Rosemary Newton for her expertise and guidance with this case and the veterinarians and staff at Quakertown Veterinary Clinic for hosting my externship. CVJ
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