ISSN 2398-2969      

Meningioma

icanis

Introduction

  • Incidence: estimates of brain neoplasia incidence vary from 2-3% of dogs to 0.015% (15 in 100,000).
  • Of brain neoplasias, meningiomas are most common.
  • Meningiomas are usually benign and slow growing.
  • Most commonly occur on the floor of the cranial cavity, over the convexities of the cerebral hemispheres or over the cerebellum, and the olfactory lobes.
  • Signs: suggest a focal space-occupying lesion, seizures, behavioral changes, circling.
  • Diagnosis: history, signs, computed tomography or MRI.
  • Treatment: corticosteroids, surgical excision, chemotherapy or radiotherapy.
  • Prognosis: depends on accessibility and size of tumor.

Pathogenesis

Pathophysiology

  • Benign neoplasm, slow growing, solitary, causes local brain compression and a zone of edema around the tumor.
  • Eventually, the size of the mass will cause a rise in intracranial pressure.
  • Neoplasia commonly involves the supratentorial structures, particularly in older animals.
  • Clinical signs can be progressive, or may occur acutely.
  • Signs reflect either primary nervous parenchymal damage from the tumor or secondary pathophysiological sequele such as hemorrhage and edema.
  • Often, these secondary sequele are more devastating to intracranial function than the primary disease itself.
  • Brain tumors have been reported to occur in dogs with a frequency of 14.5 per 100,000 at risk, however the actual incidence is probably not known.
  • With the advent of advanced imaging modalities such ascomputed tomography (CT)ormagnetic resonance imaging (MRI), the ability to diagnose brain tumors ante-mortem in dogs is increasing.
  • The authors retrospectively reviewed the medical records of 97 dogs with brain tumors diagnosed at their hospital. Most dogs had lesions of the supratentorial space (cerebral hemispheres, basal nuclei, diencephalon).
  • Meningiomas arise from the arachnoid layer of the meninges.
  • These tumors develop from the periphery of the brain parenchyma and expand inward.
  • In dogs, meningiomas tend to be more infiltrative to cortical parenchyma in comparison to cats, where meningiomas are often well encapsulated.
  • Often these tumors are calcified (psammoma bodies).
  • Meningiomas may arise intraventricularly from the tela choroidea mimicking a choroid plexus tumor.
  • Predominantly cystic meningiomas, often involving the olfactory area, have also been described.
  • Meningiomas are usually histologically benign, but occasionally are malignant.
  • Metastasis to extraneural sites is uncommon, but meningiomas have been reported to spread to the lung.
  • Solitary masses are seen in dogs.
  • In dogs, meningiomas tend to be more infiltrative to cortical parenchyma in comparison to cats, where meningiomas are often well encapsulated.
  • Benign tumor → space-occupying lesion → local brain compression and zone of edema around tumor → focal interference with brain function → slow growth → focal, slowly progressive neurological deficits.
  • Transmitted effects or brain herniation may exacerbate signs.

Timecourse

  • Meningiomas can have a timecourse of a year or more.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Bergman R et al (2000) Post-operative computed tomography in two dogs with cerebral meningioma. Vet Rad Ultra 41 (5), 425-432 PubMed.
  • Bagley R S et al (1998) Seizures as a complication of brain tumors in dogs. Clin Tech Small Anim Pract 13 (3), 179-184 PubMed.
  • Graham J P et al (1998) The dural tail sign in the diagnosis of meningiomas. Vet Radiol Ultrasound 39 (4), 297-302 PubMed.
  • Lorenzo V et al (1998) Meningioangiomatosis in a dog - magnetic resonance imaging and neuropathological studies. JSAP 39 (10), 486-489 PubMed.
  • Kraft S L et al (1997) Retrospective review of 50 canine intracranial tumors evaluated by magnetic resonance imaging. JVIM 11 (4), 218-225 PubMed.
  • Levy M S et al (1997) Spinal tumors in 37 dogs - clinical outcome and long-term survival (1987-1994). JAAHA 33 (4), 307-312 PubMed.
  • Bagley R S et al (1996) Cystic meningiomas in 2 dogs. JVIM 10 (2), 72-75 PubMed.
  • Bagley R S (1996) Pathophysiologic sequelae of intracranial disease. Vet Clin North Am Small Anim Pract 26 (4), 711-33 PubMed.
  • Moore M P, Bagley R S, Harrington M L et al (1996) Intracranial tumors. Vet Clinic North Am Small Anim Pract 26 (4), 759-77 PubMed.
  • Pumarola M et al (1996) Meningioangiomatosis in the brain stem of a dog. J Comp Pathol 115 (2), 197-201 PubMed.
  • Tucker R L & Gavin P G (1996) Brain imaging. Vet Clin North Am 26 (4), 735-58 PubMed.
  • Willis M et al (1996) What is your diagnosis? Retrobulbar meningioma in a dog. JAVMA 209 (11), 1845-1846 PubMed.
  • Gavin P R, Fike J R & Hoopes P J (1995) Central nervous system tumors. Seminars Vet Med Surg 10 (3), 180-9 PubMed.
  • Gallagher J G et al (1995) Ultrasonography of the brain and vertebral canal in dogs and cats - 15 cases (1988-1993). JAVMA 207 (10), 1320-1324 PubMed.
  • Fischer A et al (1994) What is your neurologic diagnosis? Neoplasia (meningioma, neurofibroma or lymphosarcoma). JAVMA 205 (9), 1275-1277 PubMed.
  • Fisher A (1994) What is your neurologic diagnosis? Tumor of the left portion of the brain stem. JAVMA 205 (5), 687-689 PubMed.
  • Schulman F Y, Ribas J L, Carpenter J L et al (1992) Intracranial meningioma with pulmonary metastasis in three dogs. Vet Path 29 (3), 196-202 PubMed.
  • Davidson M G, Nasisse M P, Breitschwerdt B et al (1991) Acute blindness associated with intracranial tumors in dogs and cats - eight cases (1984-1989). JAVMA 199 (6), 755-8 PubMed.
  • Heidner G L, Kornegay J N, Page R L et al (1991) Analysis of survival in a retrospective study of 86 dogs with brain tumors. JVIM 5 (4), 219-26 PubMed.
  • Foster E S, Carrillo J M & Patnaik A K (1988) Clinical signs of tumors affecting the rostral cerebrum in 43 dogs. JVIM 2 (2), 71-4 PubMed.
  • Bailey C S & Higgins R J (1986) Characteristics of cisternal cerebrospinal fluid associated with primary brain tumors in the dog - a retrospective study. JAVMA 188 (4), 414-7 PubMed.
  • Carrillo J M, Sarfaty D & Greenlee P (1986) Intracranial neoplasm and associated inflammatory response from the central nervous system. JAAHA 22 (3), 367-73 VetMedResource.
  • Turrel J M, Fike J R, LeCourteur R A et al (1986) Computed tomographic characteristics of primary brain tumors in 50 dogs. JAVMA 188 (8), 851-6 PubMed.
  • Palmer A C, Malinowski W & Barnet K C (1974) Clinical signs including papilloedema associated with brain tumors in twenty-one dogs. JSAP 15 (6), 359-86 PubMed.
  • Geib L W (1966) Ossifying meningioma with extracranial metastasis in a dog. Pathol Vet 3 (3), 247-54 PubMed.

Other sources of information

  • Bagley R S, Kornegay J N, Page R Let al(1992)Central nervous system neoplasia.In: Slatter D H (ed)Textbook of Small Animal Surgery. 3rd edn Philadelphia: W B Saunders: pp 2137.
  • Fulton L (1991)The use of lomustine in the treatment of brain masses.In:Proceedings of the Ninth Annual Veterinary Medical Forum. New Orleans, p 827.

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