Original article
Neurological diseases of unknown etiology: Brain-biopsy diagnostic yields and safety

https://doi.org/10.1016/j.ejim.2020.05.029Get rights and content

Highlights

  • In patients undergoing brain biopsy for neurological diseases of unknown etiology, we found high rates of specific histological (71.3%) and final diagnoses (83.1%), leading to therapeutic management change(s) for 75% of cases.

  • Immunodepression was independently associated with specific histological diagnosis.

  • Brain biopsy–related mortality occurred in 1.1% and permanent neurological morbidity in 0.6% of the patients.

    For highly selected patients with neurological diseases of unknown etiology, brain biopsy has a high diagnostic yield and low frequency of severe complications.

Abstract

Background

For nonneoplastic neurological diseases, no recommendation exists regarding the place or appropriate timing of brain biopsy. The aim of this study was to evaluate the diagnostic yield and safety of brain biopsies from patients with neurological diseases of unknown etiology.

Methods

We performed a retrospective cohort study from January 1, 2008 to December 31, 2018. We analyzed 1847 brain-biopsied patients, including 178 biopsies indicated for neurological diseases of unknown etiology. Specific histological and final diagnosis rates, positive diagnosis-associated factors, complication rate and complication-associated factors were assessed.

Results

Specific histological diagnosis and final diagnosis rates were 71.3% and 83.1%, respectively, leading to therapeutic management change(s) for 75.3% of patients. Brain- biopsy–related mortality and permanent neurological morbidity occurred in 1.1% and 0.6% of the patients, respectively. The multivariable logistic-regression model retained (odds ratio [95% CI] only immunodepression (2.2 [1.1–4.7]; P=.04) as being independently associated with specific histological diagnosis, while supratentorial biopsy-targeted lesions (4.1 [1.1–15.2]; P=.04) were independently associated with a final diagnosis. Biopsies obtained from comatose patients were less contributive to the diagnosis (0.2 [0.05–0.7]; P=.01). Prebiopsy platelet count <100 G/L (28.5 [1.8–447]; P=.02), hydrocephalus (6.3 [1.2–15.3]; P=.02) and targeted lesions <1 cm (4.3 [1.2–15.3]; P=.03) were independently associated with brain biopsy-related complications.

Conclusion

For highly selected patients with neurological diseases of unknown etiology, brain biopsy has a high diagnostic yield and low frequency of severe complications. We advocate that this procedure be considered early in the diagnosis algorithm of these patients.

Introduction

The contribution of brain biopsy is well-established for patients with suspected neoplastic lesions, for which its diagnostic yield approaches 95% [1,2]. For nonneoplastic neurological diseases, no recommendation exists regarding the place or appropriate timing of brain biopsy. Limited data support using brain biopsy to determine a diagnosis in human immunodeficiency virus (HIV)-positive patients with neurological symptoms [3,4], cerebral angiitis [5], Creutzfeldt–Jakob disease [6] or dementia [7]. For patients with neurological diseases of unknown etiology, brain biopsy is usually the investigational modality of last resort after exhaustive workups with less invasive tests, including imaging, cerebrospinal fluid analysis and electroencephalography, have failed to make a diagnosis. Because brain biopsy is an invasive procedure carrying a risk of severe complications, many physicians favor empirical treatments over taking the risk associated with biopsy to establish a diagnosis.

Considering the lack of evidence to guide the decision to biopsy for this challenging subgroup of patients, we conducted a retrospective monocenter study to investigate brain-biopsy diagnostic yield and safety in adults with neurological diseases of unknown etiology.

Section snippets

Patients

We retrospectively reviewed the medical records and histology reports of all adults brain-biopsied at our tertiary medical center, between January 1, 2008 and December 31, 2018. Patients meeting the following conditions were included: 1) neurological disease of unknown etiology or atypical cerebral evolution of systemic and/or neurological underlying diseases; 2) negative comprehensive less-invasive diagnostic work-up including physical examination, laboratory tests, morphological examinations

Study population

During the study period, 1847 patients underwent a brain biopsy; the 178 biopsied to investigate a neurological disease of unknown etiology were included in the study (Fig. 1). The yearly number of brain biopsies and their indications for the 1847 patients are reported in Supplemental Table 1. The main reason for those latter biopsies was the histological confirmation of an obvious primary or secondary cerebral neoplasm (n = 1504, 90.4%).

The general characteristics of the 178 retained patients

Discussion

For patients with neurological disease of unknown etiology, the place of brain biopsy remains controversial, because it is an invasive option that should only be considered when the global benefit surpasses the risk of inducing harm.

Previous series, mostly published in the 1990s and 2000s, included 14 to 64 patients brain biopsied for cryptogenic neurological disease [5,[11], [12], [13], [14], [15], [16], [17], [18], [19], [20]]. Their reported diagnostic yields were relatively low, 29–68% [11,

Conclusions

Our results suggest that, for highly selected patients with neurological diseases of unknown etiology, brain biopsy has a high diagnostic yield and low frequency of severe complications. We advocate that this procedure be considered early in the diagnosis algorithm of patients with neurological diseases of unknown etiology.

Author's contribution

All authors had access to the data and a role in writing the manuscript.

Declaration of Competing Interest

The authors declare no conflicts of interest.

Acknowledgments

We thank the French Society of Neurosurgery and Cormedica for their support.

Availability of data

On request.

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