Diagnostic Yield and Adverse Effects of MRI‐Guided Free‐Hand Brain Biopsies through a Mini‐Burr Hole in Dogs with Encephalitis

Abstract

Background: The diagnosis of encephalitis is usually presumptive based on MRI, cerebrospinal fluid analysis, or both. A definitive diagnosis based on histopathology, however, is required for optimizing treatment strategies.Objective: To investigate the diagnostic yield and adverse effects of minimally invasive brain biopsies in dogs with encephalitis.Animals: Seventeen dogs with suspected encephalitis, based on MR imaging and cerebrospinal fluid analysis. Methods: Retrospective study. Minimally invasive, free-hand brain biopsy specimens were taken from forebrain lesions through a 4-mm burr hole using a Sedan side-cutting needle. Routine histopathological examination was performed. The adverse effects were assessed by MRI evaluations after biopsy procedure (12/17) and by sequential neurological examinations.Results: The overall diagnostic yield with regard to a specific type of encephalitis was 82%. Encephalitis was evident in an additional 12%, but a specific disease could not be determined. There were no deaths caused by the biopsy procedure itself, but the indirect case fatality rate was 6%. Morbidity was 29%, including stupor, seizures, tetraparesis, hemiparesis, ataxia, and loss of conscious proprioception. All these signs resolved within 3-14 days.Conclusions and Clinical Importance: Minimally invasive brain biopsy in dogs with suspected encephalitis leads to a definite diagnosis in the majority of dogs, allowing for a specific treatment. The advantages of a definite diagnosis outweigh potential case fatality rate and temporary neurological deficits.

Perspectives on Meningoencephalomyelitis of Unknown Origin

“…4,99 For this reason there is no specific noninvasive antemortem diagnostic test, and manyother diseases can mimic the MUOs; definitive diagnosis of noninfectious inflammatory CNS disease requires histopathology. 16,100,101 However, Granger and colleagues 58 used a meta-analysis to formulate guidelines for establishing a presumptive diagnosis of MUO in the absence of histopathologic diagnosis ( Table 2): In summary, most cases diagnosed with MUO have multifocal neurologic signs, CSF mononuclear pleocytosis, and hyperintense lesions on T2-weighted (T2W) magnetic resonance (MR) imaging. 58 Although some MR imaging features are common to the NEs and GME, none are considered specific for the diagnosis of any disease process.…”

“…Antemortem brain biopsy may yield a more definite diagnosis by which to guide treatment approaches, although such procedures depend on obtaining biopsy material from representative portions of the lesion. Minimally invasive techniques such as CT-guided [127][128][129][130][131] or MR-guided 132 stereotactic systems, free-handed techniques that use ultrasound, 133 CT, 134 or MR imaging, 101 and endoscopic-guided biopsy 135 have recently been developed for brain biopsy in dogs. Diagnostic accuracy of brain biopsy in canine CNS inflammatory disease ranges from 82% to 100%, based on the limited available data, and such information highly depends on the population disease types from which the biopsies were obtained.…”

“…Diagnostic accuracy of brain biopsy in canine CNS inflammatory disease ranges from 82% to 100%, based on the limited available data, and such information highly depends on the population disease types from which the biopsies were obtained. 101,127 Diagnostic yield for biopsy of inflammatory lesions may be influenced by sample size and difficulty in distinguishing between changes in the primary and secondary lesions such as edema and necrosis. Intraoperative cytologic evaluation of the biopsy sample may aid in diagnostic accuracy.…”

Advances in Diagnostic and Treatment Modalities for Intracranial Tumors

“…In cases where surgical resection is not considered the optimal approach to treatment and diagnosis, minimally invasive biopsy techniques are considered the most appropriate way to obtain diagnostic data permitting a maximally informed approach to treatment. Free‐hand, image‐guided, and endoscope‐assisted brain biopsy has been described for dogs84, 85, 86; however, stereotactic‐guided procedures have many advantages. Both CT‐ and MRI‐based stereotactic systems were developed for dogs in the 1980s in the experimental setting,87, 88 and a variety of stereotactic approaches to clinical brain biopsy have been described in dogs and cats, the majority of which have involved CT‐based systems 89, 90, 91, 92, 93, 94, 95.…”

Clinical, Imaging and Pathological Characteristics of Brain Implanted Polylactic Co-Glycolic Acid Polymers Conjugated with Temozolomide

“…For our study, microcylinders that are amenable to stereotactically-guided implantation were created, and have the potential to allow treatment of either surgically accessible or inaccessible tumours in a minimally-invasive manner. Stereotactic guidance systems have been validated for use in dogs previously using both CT and MRI [38][39][40][41][42][43][44][45].…”