ISSN 2398-2969      

Partial seizures

icanis

Synonym(s): Complex partial seizures; Aura; Psychomotor seizures; Fly-catching


Introduction

  • Cause: often related to a structural cerebrocortical (forebrain) lesion however, it can be seen with primary epilepsy.
  • Signs: partial seizures may be simple or complex and may or may not generalize.
  • Diagnosis: advance imaging of the brain and cerebrospinal fluid analysis along with a complete metabolic investigation (ie hematology, biochemistry, systemic blood pressure, thoracic and abdominal radiography) depending on the case.
  • Treatment: treatment with anti-convulsant medications and management of underlying structural brain disease if one is identified.
  • Prognosis: depends on nature of any underlying structural brain disease if one is identified. Also dependent on response to anti-convulsant medications.

Pathogenesis

Etiology

  • Partial seizures may be secondary to a structural lesion in the cerebral cortex.
  • Any structural brain disease (ie vascular, inflammatory/infectious, traumatic, anomalous, neoplastic) can potentially cause partial seizures if it affects the forebrain.
  • Cats more commonly have partial seizures rather than generalized seizures. Historically, focal seizures have been associated with structural lesions of the forebrain; however, in the authors experience, the presence of focal seizures does not rule-out a diagnosis of primary epilepsy, especially in cats.

Predisposing factors

General
  • Seizures may be triggered by exciting stimuli such as bright light, loud noises and stressful situations although many occur whilst the patient is resting.

Specific

  • Specific triggers such as focal brain damage due to trauma may cause partial seizures.
    Toxins and metabolic diseases are more likely to trigger generalized seizures than partial ones.

Pathophysiology

  • Partial seizures originate from a focal area in the cerebrocortex.
  • Complex partial seizures have a temporal or frontotemporal origin and epileptiform discharges are frequently bilateral. So called psychomotor seizures can be induced experimentally in cats by destruction of the pyriform hippocampus. This is part of the limbic system which serves to modulate emotional expression, eg rage, sexual activity, fear many of these have also been observed in dogs with spontaneous psychomotor seizures.
  • Both simple and complex partial seizures may progress to generalized seizures (secondary generalization)
  • Partial seizures are the manifestation of excessive spontaneous or hypersynchronous neuronal discharge in a focal region of the forebrain.

Timecourse

  • The ictal period (ie actual seizure event) lasts usually from seconds to minutes. Post-ictal signs typically last a few minutes to hours.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Ruehlmann D, Podell M, March P (2001) Treatment of partial seizures and seizure-like activity with felbamate in six dogs. JSAP 42 (8), 403-408 PubMed.
  • Stonehewer J, Mackin A J, Tasker S, Simpson J W, Mayhew I G (2000) Idiopathic phenobarbital-responsive hypersialosis in the dog: an unusual form of limbic epilepsy? JSAP 41 (9), 416-421 PubMed.
  • Berendt M, Gram L (1999) Epilepsy and seizure classification in 63 dogs: a reappraisal of veterinary epilepsy terminology. JVIM 13 (1), 14-20 PubMed.
  • Dodman N H, Knowles K E, Shuster L (1996) Behavioural changes associated with suspected complex partial seizures in Bull Terriers. JAVMA 208 (5), 668-691 PubMed.
  • Holland C T (1988) Successful long term treatment of a dog with psychomotor seizures using carbamazepine. Aus Vet J 65 (12), 389-392 PubMed.

Other sources of information

  • Thomas W B (2010)Idiopathic epilepsy in dogs and cats.Vet Clin Small Anim40,161-179.
  • Podell M (2004)Seizures.In:BSAVA Manual of canine and feline neurology.3rd edition.Platt S R & Olby N J eds. BSAVA publication.
  • www.canineepilepsy.co.uk

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