Peripheral nerve sheath tumors in dogs are well described, but diagnosis and treatment remain challenging. These tumors may involve spinal and peripheral nerves, including those arising from the cervical and lumbosacral intumescences in particular.1–6 Chronic lameness in 1 leg is a frequent clinical sign.1–6 For this reason, it is difficult to differentiate between PNSTs and orthopedic conditions.1–6 Progressive hemiparesis or tetraparesis occurs in patients with spinal invasion of the cervicothoracic region.1 Peripheral nerve sheath tumors grow proximally and therefore tend to invade the intervertebral foramen and the vertebral canal. Peripheral nerve sheath tumors may affect 1 or several nerve roots, but it remains unclear whether they initially occur in multifocal areas or whether they spread from 1 root to another.7
Surgical treatment in dogs involves excision of the tumor (and nerve), limb amputation, and laminectomy, when indicated.1–3,5,6,8 Intraoperative determination of the affected root and invasion into the foramen by the PNST remain challenging.3 In a study of 51 histologically confirmed cases of PNST in dogs, Brehm et al1 found that 23 (45%) tumors invaded the intervertebral foramen (the root group). This group had a disease-free interval of 1 month and a median survival time of only 5 months, even with surgical treatment.
Electromyography has been described as a sensitive tool for detecting the neuropathic changes associated with these tumors.1,9 Nerve conduction studies4,9–11 have been described in a few cases with absent CMAPs or reduced nerve conduction velocity. Electromyography of epaxial muscles has rarely been performed in veterinary patients with PNSTs.10 However, such techniques are theoretically of interest for identifying tumor extension into the intervertebral foramen or the vertebral canal.12 Myelography may be useful for documenting vertebral canal invasion by the tumor.1 In peripheral locations, this technique has been supplanted by CT and MRI. However, a lack of contrast uptake or heterogeneous enhancement (after IV contrast products injection) may make it difficult to distinguish the tumor from the surrounding tissues, making diagnosis and localization difficult.4,11,13,14
In the study reported here, we aimed to review our knowledge concerning the electrophysiological characteristics of PNSTs and to identify features or variables correlated with the duration of clinical signs. Our secondary objective was to determine whether any of these features were predictive of proximal invasion by the PNST. Our third objective was to evaluate whether knowledge of the electrophysiological results could be helpful in interpreting imaging findings for the diagnosis of PNSTs via CT or MRI.
Compound muscle action potential
Motor nerve conduction velocity
Peripheral nerve sheath tumor
le Chevoir M, Thibaud JL, Blot S. Electromyography and electroneurography, a standard but current technique in the diagnosis of peripheral nerve sheath tumors: retrospective study of 39 cases, in Proceedings. 23rd Annu Symp Eur Soc Vet Neurol Eur Coll Vet Neurol 2010;56.
CLOVIS, clinical software of the national schools of Veterinary Medicine of Alfort, Lyon, Nantes and Toulouse, Computing Department, Ecole Nationale Vétérinaire de Lyon, Marcy-l'Étoile, France.
Nicolet Viking Select, Viasys Healthcare, Madison, Wis.
Nicolet Viking IV P, Viasys Healthcare, Madison, Wis.
Rapinovet, Schering-Plough/Merck, Whitehouse Station, NJ.
Nesdonal, Mérial, Lyon, France.
CE 10000, General Electric, Milwaukee, Wis.
CT Pace, General Electric, Milwaukee, Wis.
Hispeed Dual Xtream, General Electric, Milwaukee, Wis.
Brightspeed, General Electric, Milwaukee, Wis.
Telebrix, Guerbet, Villepinte, France.
Signa Profile, 0.2 T, General Electric, Milwaukee, Wis.
Dotarem, Guerbet, Villepinte, France.
Statistics Data Analysis, version 9.1, StataCorp, College Station, Tex.
Platt SR, McConnell JF, Dennis R, et al. Chronic canine hypertrophic neuritis mimicking nerve sheath tumours on advanced imaging, 3 cases (abstr). J Vet Intern Med 2006;21:1145–1146.
Walmsley G, Mantis P, Cappello R. Magnetic resonance imaging of focal radiculopathy (abstr). J Vet Intern Med 2006;21:1162.
Matiasek K, Steffen F, Schmahl W, et al. Back to the roots: radicular pathology in foraminal stenosis (abstr). J Vet Intern Med 2007;22:514.
1. Brehm DM, Vite CH, Steinberg HS, et al. A retrospective evaluation of 51 cases of peripheral nerve sheath tumors in the dog. J Am Anim Hosp Assoc 1995; 31:349–359.
2. Targett MP, Dyce J, Houlton JEF. Tumours involving the nerve sheaths of the forelimb in dogs. J Small Anim Pract 1993; 34:221–225.
4. Abraham LA, Mitten RW, Beck C, et al. Diagnosis of sciatic nerve tumour in two dogs by electromyography and magnetic resonance imaging. Aust Vet J 2003; 81:42–46.
5. Montoliu P, Pumarola M, Zamora A, et al. Femoral mononeuropathy caused by a malignant sarcoma: two case reports. Vet J 2008; 178:298–301.
6. Harcourt-Brown TR, Granger N, Smith PM, et al. Use of a lateral surgical approach to the femoral nerve in the management of two primary femoral nerve sheath tumours. Vet Comp Orthop Traumatol 2009; 22:229–232.
7. Koestner A, Higgins RJ. Tumors of the nervous system. In: Meuten DJ, eds. Tumors in domestic animals. 4th ed. Iowa: Blackwell Publishing Co, 2002;697–738.
8. Steinberg HS. Brachial plexus injuries and dysfunctions. Vet Clin North Am Small Anim Pract 1988; 18:565–580.
10. Chrisman CL. Electromyography in the localization of spinal cord and nerve root neoplasia in dogs and cats. J Am Vet Med Assoc 1975; 166:1074–1079.
11. McCarthy RJ, Feeney DA, Lipowitz AJ. Preoperative diagnosis of tumors of the brachial plexus by use of computed tomography in three dogs. J Am Vet Med Assoc 1993; 202:291–294.
12. Kimura J. Examination of non limb muscles. In: Kimura J, eds. Electrodiagnosis in diseases of nerve and muscle: principles and practice. 3rd ed. New York: Oxford University Press Co, 2001;370–383.
13. Rudich SR, Feeney DA, Anderson KL, et al. Computed tomography of masses of the brachial plexus and contributing nerve roots in dogs. Vet Radiol Ultrasound 2004; 45:46–50.
14. Kraft S, Ehrhart EJ, Gall D, et al. Magnetic resonance imaging characteristics of peripheral nerve sheath tumors of the canine brachial plexus in 18 dogs. Vet Radiol Ultrasound 2007; 48:1–7.
17. Summers BA, Cummings JF, de Lahunta A. Neoplasia and the peripheral nervous system. In: Summers BA, ed. Veterinary neuropathology. St Louis: Mosby-Year Book, 1995;472–481, 499–501.
18. Thyagarajan D, Cascino T, Harms G. Magnetic resonance imaging in brachial plexopathy of cancer. Neurology 1995; 45:421–427.
19. Hermanson JW, Evans HE. The muscular system. In: Evans HE, ed. Miller's anatomy of the dog. 3rd ed. Philadelphia: WB Saunders Co, 1993;258–384.
20. Bailey CS. Long-term survival after surgical excision of a schwannoma of the sixth cervical spinal nerve in a dog. J Am Vet Med Assoc 1990; 196:754–756.
21. Walmsley G, Scurrell E, Summers B, et al. Foreign body induced neuritis masquerading as a canine brachial plexus nerve sheath tumour. Vet Comp Orthop Traumatol 2009; 22:427–429.
23. Cummings JF, Cooper BJ, de Lahunta A, et al. Canine inherited hypertrophic neuropathy. Acta Neuropathol 1981; 53:137–143.
24. Cummings JF, Lorenz MD, de Lahunta A, et al. Canine brachial plexus neuritis: a syndrome resembling serum neuritis in man. Cornell Vet 1973; 63:589–617.