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50 Section I: Diagnostics and Planning

study aimed to determine the mean needle placement error in the <1%) [157–160]. In addition, it should be remembered that due to
caudate nucleus, thalamus, and midbrain of a canine cadaver brain the small volume of tissue yielded during needle biopsy procedures,
using the modified Brainsight stereotactic system. Relocatable it is fairly common to obtain a nondiagnostic sample, especially if a
fiducial markers were attached to a cadaver head using a dental nonrepresentative part of the tumor is targeted. It is therefore
bite block. A T1‐weighted GRE three‐dimensional sequence was extremely helpful to perform cytology or to preserve frozen sec-
acquired using set parameters. Fiducial markers were used to regis- tions during the procedure to ensure that a representative sample
ter the head to the acquired images in reference to a three‐dimen- has been obtained.
sional position sensor. This allowed the planning of trajectory path
to brain targets in real time. Coordinates (x, y, z) were established Video clips to accompany this book can be found on
for each target and 0.5 μL of diluted gadolinium was injected at each the companion website at:
target using a 26 G needle to create a lesion. The center of the gado- www.wiley.com/go/shores/neurosurgery
linium deposition was identified on the postoperative images and
coordinates (x′, y′, z′) were established. The precision of this system
in bringing the needle to target (needle placement error) was calcu- References
lated. Seventeen sites were targeted in the brain. The mean needle 1 Bar‐Am Y, Pollard RE, Kass PH, Verstraete FJ. The diagnostic yield of conventional
placement error for all target sites was 1.79 ± 0.87 mm. The upper radiographs and computed tomography in dogs and cats with maxillofacial trauma.
bound of error for this stereotactic system was 3.31 mm. There was Vet Surg 2008;37:294–299.
no statistically significant relationship between needle placement 2 Doust R, King A, Hammond G et al. Assessment of middle ear disease in the dog: a
comparison of diagnostic imaging modalities. J Small Anim Pract 2007;48: 188–192.
error and target depth (P = 0.23). The ease of use and precision of 3 Smith CW, Marshall AE, Knecht CD. Detection of artificially produced intracranial
this stereotactic system support its development for clinical use in midline shifts of the brain in the dog with A‐mode echoencephalography. Am J Vet
dogs with brain lesions larger than 3.31 mm [161]. Res 1972;33:2423–2427.
4 Smith CW, Marshall AE, Knecht CD. Use of A‐mode echoencephalography in the
dog. Am J Vet Res 1972;33:2415–2421.
Summary 5 Hudson JA, Finn‐Bodner ST, Steiss JE. Neurosonography. Vet Clin North Am Small
The decision regarding which method to use is dictated primarily Anim Pract 1998;28:943–972.
by the facilities available to the neurosurgeon. Other factors that 6 Harrington ML, Bagley RS, Moore MP. Hydrocephalus. Vet Clin North Am Small
Anim Pract 1996;26:843–856.
need to be considered include the appearance of the lesion on CT 7 Tucker RL, Gavin PR. Brain imaging. Vet Clin North Am Small Anim Pract
and/or MRI, the location of the lesion (intraaxial vs. extraaxial), 1996;26:735–758.
and the neurological status of the patient. If the neurological status 8 Brown JA, Rachlin J, Rubin JM, Wollmann RL. Ultrasound evaluation of experi-
mental hydrocephalus in dogs. Surg Neurol 1984;22:273–276.
of the patient is poor and raised ICP is suspected, a craniectomy 9 Platt SR, Graham J, Chrisman CL et al. Magnetic resonance imaging and ultra-
and biopsy may be performed to allow decompression and allevia- sonography in the diagnosis of a malignant peripheral nerve sheath tumor in a dog.
tion of the clinical signs, in addition to providing tissue for diagno- Vet Radiol Ultrasound 1999;40:367–371.
sis. However, lesions in deep structures may be difficult to biopsy 10 Thomas WB, Sorjonen DC, Hudson JA, Cox NR. Ultrasound‐guided brain biopsy
via an open craniectomy. This particularly applies to lesions in the in dogs. Am J Vet Res 1993;54:1942–1947.
deep gray matter of the forebrain (e.g., thalamus and hypothala- 11 Brown FD, Rachlin JR, Rubin JM, Fessler RG, Smith LJ, Schaible KL. Ultrasound‐
guided periventricular stereotaxis. Neurosurgery 1984;15:162–164.
mus) or brainstem (e.g., medulla oblongata). In this situation, ste- 12 Chandrana C, Bevan P, Hudson J et al. Development of a platform for co‐registered
reotactic needle biopsy may be preferable, if available, as it causes ultrasound and MR contrast imaging in vivo. Physics Med Biol 2011;56:861–877.
less damage to vital structures. With lesions that are thought to be 13 Noureddine C, Harder R, Olby NJ, Spaulding K, Brown T. Ultrasonographic
very vascular, based on their imaging characteristics, conventional appearance of Dandy Walker‐like syndrome in a Boston Terrier. Vet Radiol
Ultrasound. 2004;45:336–339.
biopsy obtained via a craniectomy may be more desirable than a 14 Saito M, Olby NJ, Spaulding K. Identification of arachnoid cysts in the quadrigemi-
needle biopsy as hemorrhage can be controlled intraoperatively. nal cistern using ultrasonography. Vet Radiol Ultrasound. 2001;42:435–439.
Stereotactic biopsy is also associated with complications, 15 Gallagher JG, Penninck D, Boudrieau RJ, Schelling SH, Berg J. Ultrasonography of
although these are generally rare. The most common problem is the brain and vertebral canal in dogs and cats: 15 cases (1988–1993). J Am Vet Med
Assoc 1995;207:1320–1324.
hemorrhage caused by the biopsy procedure; this may lead to sig- 16 Werner C, Hoffman WE, Kochs E, Albrecht RF, Schulte am Esch J. Transcranial
nificant neurological deficits and can be life‐threatening. To pre- Doppler sonography indicates critical brain perfusion during hemorrhagic
vent this, the trajectory of the biopsy needle must be planned hypotension in dogs. Anesth Analg 1995;81:1203–1207.
carefully in order to avoid major blood vessels and care should be 17 Rim SJ, Leong‐Poi H, Lindner JR et al. Quantification of cerebral perfusion with
“real‐time” contrast‐enhanced ultrasound. Circulation 2001;104:2582–2587.
taken if imaging findings suggest the lesion is highly vascular (e.g., 18 Hudson JA, Buxton DF, Cox NR et al. Color flow Doppler imaging and Doppler spec-
choroid plexus papilloma). In addition, it is important to maintain tral analysis of the brain of neonatal dogs. Vet Radiol Ultrasound 1997; 38:313–322.
normal systemic blood pressure during surgery, as hypertension in 19 Saito M, Olby NJ, Spaulding K, Munana K, Sharp NJ. Relationship among basilar
humans has been reported to increase the risk of hemorrhage fol- artery resistance index, degree of ventriculomegaly, and clinical signs in hydroce-
lowing biopsy. As with conventional craniectomy, postoperative phalic dogs. Vet Radiol Ultrasound 2003;44:687–694.
imaging is recommended following needle biopsy to detect hemor- 20 Fukushima U, Miyashita K, Okano S, Higuchi S, Takase K, Hagio M. Evaluation of
intracranial pressure by transcranial Doppler ultrasonography in dogs with intrac-
rhage. Close monitoring of the patient’s neurological status should ranial hypertension. J Vet Med Sci 2000;62:353–355.
also be performed for 48 hours following the procedure and scan- 21 Carvalho CF, Perez RB, Chamas MC, Maiorka PC. Transcranial Doppler sono-
ning should be repeated if any deterioration in the level of con- graphic findings in granulomatous meningoencephalitis in small breed dogs. Can
Vet J 2012;53:855–859.
sciousness occurs. In rare cases, a craniectomy may be required to 22 Fukushima U, Sasaki S, Okano S et al. Non‐invasive diagnosis of ischemic brain
alleviate raised ICP or to adequately control hemorrhage. damage after cardiopulmonary resuscitation in dogs by using transcranial Doppler
A rare complication reported in humans is “seeding” of a tumor ultrasonography. Vet Radiol Ultrasound 2000;41:172–177.
along the needle tract. Morbidity and mortality rates associated 23 Britt RH, Lyons BE, Enzmann DR, Saxer EL, Bigner SH, Bigner DD. Correlation of
with brain biopsy in dogs and cats are 12–26% and 7–8%, respec- neuropathologic findings, computerized tomographic and high‐resolution ultra-
tively, and are higher than in humans (morbidity 3.5%, mortality sound scans of canine avian sarcoma virus‐induced brain tumors. J Neurooncol
1987;4:243–268.