Porencephaly and cortical dysplasia as cause of seizures in a dog
© Machado et al.; licensee BioMed Central Ltd. 2012
Received: 7 August 2012
Accepted: 20 December 2012
Published: 27 December 2012
Seizures are a common problem in small animal neurology and it may be related to underlying diseases. Porencephaly is an extremely rare disorder, and in Veterinary Medicine it affects more often ruminants, with only few reports in dogs.
A one-year-old intact male Shih-Tzu dog was referred to Veterinary University Hospital with history of abnormal gait and generalized tonic-clonic seizures. Signs included hypermetria, abnormal nystagmus and increased myotatic reflexes. At necropsy, during the brain analysis, a cleft was observed in the left parietal and occipital lobes, creating a communication between the subarachnoid space and the left lateral ventricle, consistent with porencephaly; and also a focal atrophy of the caudal paravermal and vermal portions of the cerebellum. Furthermore, the histological examination showed cortical and cerebellar neuronal dysplasia.
Reports of seizures due to porencephaly are rare in dogs. In this case, the dog presented a group of brain abnormalities which per se or in assemblage could result in seizure manifestation.
Seizures are a common problem in small animal neurology and it may be related to underlying diseases. Brain anomaly associated with seizures was described in 4.16% of 240 dogs in a retrospective study .
Porencephaly is an extremely rare disorder of the central nervous system (CNS) involving a cavity filled with cerebrospinal fluid (CSF), in the brain's parenchyma, usually connecting the ventricles to the brain surface. The lesion is associated with ischemic or hemorrhagic episodes and is characterized by a cavity, or cavitations in brain tissue, of variable size and location, given different names according to presumed mechanism and morphology . Extensive porencephaly communicates through the subarachnoid space to the ventricles, which shows similar morphological findings to those of open-lip schizencephaly. Patients with these two types of defective lesions present with severe developmental delays and intractable epilepsy . Cavitation in schizencephaly is lined by dysplastic cortex, usually associated with polymicrogyria . Comparing with hydranencephaly, porencephaly describes less extensive defect in the cerebral walls, which may not communicate with the CSF compartments .
The main causes of porencephaly in humans seem to be vascular cerebral lesions caused by traumatism, infections or congenital defects [6, 7]. In cases of congenital porencephaly, the cause can be genetic or due to perinatal vascular lesions [2, 7]. In Veterinary Medicine, cases of porencephaly are infrequently described in cattle, sheep and goats, and they are usually related to viral infections such as Akabane virus, bovine viral diarrhea and ovine gammaherpesvirus [8–11]. In sheep, porencephaly and hydrocephaly may be related to copper deficiency .
There are few reports of porencephaly in dogs and cats. Mackillop  diagnosed a case by magnetic resonance imaging (MRI) in a Labrador Retriever dog, where the author suspected that the condition was secondary to a prenatal forebrain infarct. Other recent publications about CSF-filled cavities reported cases of porencephaly in dogs and cats also diagnosed by MRI [5, 14]. This infrequent lesion should be considered as differential in cases of seizures, and therefore, the aim of this article is to describe the clinical and pathological aspects of a dog with porencephaly.
Neurological examination of the dog with porencephaly and focal cerebellar vermis atrophy
ataxia, forelimb hypermetria, weak gait
flaccid tetraparesis, hindlimbs more affected than forelimbs
increased in all four limbs
present in forelimbs, absent in hindlimbs
Pupillary light reflex
normal, both direct and consensual
delayed response superficial pain, normal deep pain
Porencephaly is an uncommon cerebral disorder in animals with almost nonexistent reports in dogs [5, 13]. Seizures have been documented in animals with congenital abnormalities such as hydrocephaly, lissencephaly, and porencephaly [5, 15].
In dogs, brain anomalies could be related to seizures in a low percentage of cases (4.16%) , however there are only few previous reports of seizures associated with porencephaly in this species . On the other hand, seizures as consequence of idiopathic epilepsy are the most common brain disease in dogs . Furthermore, reports of epilepsy due to focal cortical dysplasia in animals, as well as descriptions of neuronal malformation, are rare [17, 18]. Although there is not a clear correlation between porencephaly and seizures, authors reported that porencephaly is often accompanied by amygdalar-hippocampal atrophy, which is usually related to the occurrence of seizures . Hippocampal atrophy was also noticed in the case reported herein.
The main clinical manifestation of porencephaly is the occurrence of seizures [5, 14], whereas the other clinical signs that the dog presented with, such as ataxia, dysmetria, intention tremors are related to vestibulo-cerebellar abnormalities [20, 21]. Further association between vestibulo-cerebellar signs and porencephaly was observed in dogs and cats by Schmidt et al. , but without any noticeable cerebellar lesion. In the case reported herein it was detected a focal cerebellar vermis atrophy as well as low cellularity of the granule cell layer, which may be associated to the vestibulo-cerebellar signs, since cerebellar abnormalities associated with ataxia are frequently described in dogs, including degeneration, hypoplasia and localized defects [20–25].
In this case, CSF evaluation was normal. The dog had anesthetic complications without any apparent cause and died, and according to Gaynor et al. , it is a rare condition that might be associated with hypotension or cardiac dysrhythmias. The generic clinical signs render difficult the diagnosis of porencephaly; for humans, there is the possibility of mutation identification by molecular research , however, this is currently not applicable for animals.
The major gross alteration presented herein is consistent with porencephaly. We also found cerebral neuronal dysplasia and cerebellar vermis focal atrophy. Even though porencephaly has been associated with viral infections and nutritional deficit in ruminants and vascular disturbs in humans, the specific cause in dogs remains undetermined [7, 15]. Viral infection is thought to affect endothelial cells during pregnancy and consequently causes vascular lesion and extensive loss of brain tissue, leading to the formation of cavitations [5, 9, 10]. Furthermore, the paucity of case reports make impossible to attribute this condition to a genetic predisposition of a specific breed. Consequently, since no cause could be determined, we describe herein a case of encephaloclastic (destructive) porencephaly, as suggested by Schmidt et al. .
Porencephaly is an extremely rare disorder of the brain, with no previous description in Shih-Tzu dogs, and this report gives additional evidences to relate porencephaly to the occurrence of seizures. Therefore, as observed by Davies et al.  as well as in the case described herein, porencephaly must be considered as a differential diagnosis when associated to seizures. In this particular case, the additional clinical findings detected could be related to a vestibulo-cerebellar lesion, with no correlation to porencephaly. Consequently, we described herein a case of encephaloclastic porencephaly, neuronal dysplasia and a focal atrophy in the caudal cerebellar vermis, affecting the same animal and promoting the manifestation of a particular clinical condition.
Orally informed consent was obtained from the owner of the dog for publication of this case report.
- Pákozdy Á, Leschnnik M, Tichy GA, Thalhammer GJ: Retrospective clinical comparison of idiopathic versus symptomatic epilepsy in 240 dogs with seizures. Acta Vet Hung. 2008, 56: 471-483. 10.1556/AVet.56.2008.4.5.View ArticlePubMedGoogle Scholar
- Govaert P: Prenatal Stroke. Sem Fetal Neonatal Med. 2009, 14: 250-266. 10.1016/j.siny.2009.07.008.View ArticleGoogle Scholar
- Shimizu M, Maeda T, Izumi T: The differences in epileptic characteristics in patients with porencephaly and schizencephaly. Brain Dev. 2011, 34: 546-552.View ArticlePubMedGoogle Scholar
- Pascual-Castroviejo I, Pascual-Pascual SI, Velazquez-Fragua R: Esquisencefalia. Estudio de 16 pacientes. Neurologia. 2011, 10.1016/j.nrl.2011.06.005.Google Scholar
- Davies ESS, Volk HA, Behr S, Summers B, de Lahunta A, Syme H, Jull P, Garosi L: Porencephaly and hydranencephaly in six dogs. Vet Rec. 2012, 170 (7): 179-10.1136/vr.100109.View ArticlePubMedGoogle Scholar
- Tominaga I, Kaïhou M, Kimura T, Onaya M, Kashima H, Kato Y, Tamagawa K: Cytomegalovirus fetal infection. Porencephaly with polymicrogyria in a 15-year-old boy. Rev Neurol. 1996, 152: 479-482.PubMedGoogle Scholar
- Tonni G, Ferrari B, Defelice C, Gentini G: Neonatal porencephaly in very low birth weight infants: Ultrasound timing of asphyxial injury and neurodevelopmental outcome at two years of age. J Matern Fetal Neonatal Med. 2005, 18: 361-365. 10.1080/14767050400029574.View ArticlePubMedGoogle Scholar
- Charles JA: Virus Akabane. Vet Clin North Am Pract Food Anim. 1994, 10: 525-546.Google Scholar
- Hewicker-Trautwein M, Liess B, Trautwein G: Brain lesions in calves following transplacental infection with bovine-virus diarrhea virus. Zentralbl Veterinarmed B. 1995, 42: 65-77.PubMedGoogle Scholar
- Richardson C, Taylor WP, Terlecki S, Gibbs EP: Observations on transplacental infection with bluetongue virus in sheep. Am J Vet Res. 1985, 46: 1912-1922.PubMedGoogle Scholar
- Schild AL, Riet-Correa F, Fernandes CG, Damé MC, Graça DL: Cerebellar hypoplasia and porencephaly in charolais catlle in southern Brazil. Cienc Rural. 2001, 31: 149-153. 10.1590/S0103-84782001000100025.View ArticleGoogle Scholar
- Sanders JE, Chaplin ER: Porencephaly and cytomegalovirus surviving monozygotic twin. J Pediatr. 1981, 99: 500.View ArticleGoogle Scholar
- Mackillop E: Magnetic resonance imaging of intracranial malformations in dogs and cats. Vet Radiol Ultrasound. 2011, 52: 42-51.View ArticleGoogle Scholar
- Schmidt MJ, Klumpp S, Amort K, Jawinski S, Kramer M: Porencephaly in dogs and cats: magnetic resonance imaging findings and clinical signs. Vet Radio & Ultrasound. 2012, 53 (2): 142-149. 10.1111/j.1740-8261.2011.01887.x.View ArticleGoogle Scholar
- Summers BA, Cummings JF, de Lahunta A: Veterinary neuropathology. St. Louis, MO: Mosby; 1995.Google Scholar
- Thomas WB: Idiopathic epilepsy in dogs and cats. Vet Clin North Am Small Anim Pract. 2010, 40: 161-179. 10.1016/j.cvsm.2009.09.004.View ArticlePubMedGoogle Scholar
- Cantile C, Chianini F, Arispici M, Fatzer R: Necrotizing meningoencephalitis associated with cortical hippocampal hamartia in a Pekingese dog. Vet Pathol. 2001, 38: 119-122. 10.1354/vp.38-1-119.View ArticlePubMedGoogle Scholar
- Buckmaster PS, Smith MO, Buckmaster CL, LeCouteur RA, Dudek FE: Absence of temporal lobe epilepsy pathology in dogs with medically intractable epilepsy. J Vet Int Med. 2002, 16 (1): 95-99. 10.1111/j.1939-1676.2002.tb01612.x.View ArticleGoogle Scholar
- Ho SS, Kuzniecky RI, Gilliam F, Faught E, Bebin M, Morawetz R: Congenital porencephaly: MR features and relationship to hippocampal sclerosis. Am J Neuroradiol. 1998, 19: 135-141.PubMedGoogle Scholar
- Flegel T, Matiasek K, Henke D, Greve V: Cerebellar cortical degeneration with selective granule cell loss in Bavarian mountain dog. J Small Anim Pract. 2007, 48: 462-446. 10.1111/j.1748-5827.2006.00257.x.View ArticlePubMedGoogle Scholar
- Kornegay JN: Cerebellar vermian hypoplasia in dogs. Vet Pathol. 1986, 23: 374-379. 10.1177/030098588602300405.View ArticlePubMedGoogle Scholar
- Gandini G, Botteron C, Brini E, Fatzer R, Diana A, Jaggy A: Cerebellar cortical degeneration in three English bulldogs: clinical and neuropathological findings. J Small Anim Pract. 2005, 46: 291-294. 10.1111/j.1748-5827.2005.tb00323.x.View ArticlePubMedGoogle Scholar
- Gumber S, Cho YD, Morgan TW: Late onset of cerebellar abiotrophy in a boxer dog. Vet Med Int. 2010, 2010: 1-4.Google Scholar
- Speciale J, De Lahunta A: Cerebellar degeneration in a mature Staffordshire terrier. J Am Anim Hosp Assoc. 2003, 39: 459-462.View ArticlePubMedGoogle Scholar
- Tago Y, Katsuta O, Tsuchitani M: Granule cell type cerebellar hypoplasia in a beagle dog. Lab Anim. 1993, 27: 151-155. 10.1258/002367793780810324.View ArticlePubMedGoogle Scholar
- Gaynor JS, Dunlop CI, Wagner AE, Wertz EM, Golden AE, Demme WC: Complications and mortality associated with anesthesia in dogs and cats. J Am Anim Hosp Assoc. 1999, 35: 13-17.View ArticlePubMedGoogle Scholar
- Shah S, Kumar Y, McLean B, Churchill A, Stoodley N, Rankin J, Rizzu P, van der Knaap M, Jardine P: A dominantly inherited mutation in collagen IV A1 (COL4A1) causing childhood onset stroke without porencephaly. Eur J Paediatr Neurol. 2010, 14: 182-187. 10.1016/j.ejpn.2009.04.010.View ArticlePubMedGoogle Scholar
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