Multimodal assessment improves neuroprognosis performance in clinically unresponsive critical-care patients with brain injury.

Accurately predicting functional outcomes for unresponsive patients with acute brain injury is a medical, scientific and ethical challenge. This prospective study assesses how a multimodal approach combining various numbers of behavioral, neuroimaging and electrophysiological markers affects the performance of outcome predictions. We analyzed data from 349 patients admitted to a tertiary neurointensive care unit between 2009 and 2021, categorizing prognoses as good, uncertain or poor, and compared these predictions with observed outcomes using the Glasgow Outcome Scale-Extended (GOS-E, levels ranging from 1 to 8, with higher levels indicating better outcomes). After excluding cases with life-sustaining therapy withdrawal to mitigate the self-fulfilling prophecy bias, our findings reveal that a good prognosis, compared with a poor or uncertain one, is associated with better one-year functional outcomes (common odds ratio (95% CI) for higher GOS-E: OR = 14.57 (5.70-40.32), P < 0.001; and 2.9 (1.56-5.45), P < 0.001, respectively). Moreover, increasing the number of assessment modalities decreased uncertainty (OR = 0.35 (0.21-0.59), P < 0.001) and improved prognostic accuracy (OR = 2.72 (1.18-6.47), P = 0.011). Our results underscore the value of multimodal assessment in refining neuroprognostic precision, thereby offering a robust foundation for clinical decision-making processes for acutely brain-injured patients. ClinicalTrials.gov registration: NCT04534777 .

Prognosis of glioblastoma patients improves significantly over time interrogating historical controls.

BACKGROUND: Glioblastoma (GBM) is the most common devastating primary brain cancer in adults. In our clinical practice, median overall survival (mOS) of GBM patients seems increasing over time. METHODS: To address this observation, we have retrospectively analyzed the prognosis of 722 newly diagnosed GBM patients, aged below 70, in good clinical conditions (i.e. Karnofsky Performance Status -KPS- above 70%) and treated in our department according to the standard of care (SOC) between 2005 and 2018. Patients were divided into two groups according to the year of diagnosis (group 1: from 2005 to 2012; group 2: from 2013 to 2018). RESULTS: Characteristics of patients and tumors of both groups were very similar regarding confounding factors (age, KPS, MGMT promoter methylation status and treatments). Follow-up time was fixed at 24 months to ensure comparable survival times between both groups. Group 1 patients had a mOS of 19 months ([17.3-21.3]) while mOS of group 2 patients was not reached. The recent period of diagnosis was significantly associated with a longer mOS in univariate analysis (HR=0.64, 95% CI [0.51 - 0.81]), p < 0.001). Multivariate Cox analysis showed that the period of diagnosis remained significantly prognostic after adjustment on confounding factors (adjusted Hazard Ratio (aHR) 0.49, 95% CI [0.36-0.67], p < 0.001). CONCLUSION: This increase of mOS over time in newly diagnosed GBM patients could be explained by better management of potentially associated non-neurological diseases, optimization of validated SOC, better management of treatments side effects, supportive care and participation in clinical trials.

A randomized double-blind placebo-controlled trial of low-dose interleukin-2 in relapsing-remitting multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is associated with regulatory T cells (Tregs) insufficiency while low-dose interleukin-2 (IL2LD) activates Tregs and reduces disease activity in autoimmune diseases. METHODS: We aimed at addressing whether IL2LD improved Tregs from MS patients. MS-IL2 was a single-center double-blind phase-2 study. Thirty patients (mean [SD] age 36.8 years [8.3], 16 female) with relapsing-remitting MS with new MRI lesions within 6 months before inclusion were randomly assigned in a 1:1 ratio to placebo or IL-2 at 1 million IU, daily for 5 days and then fortnightly for 6 months. The primary endpoint was change in Tregs at day-5. RESULTS: Unlike previous trials of IL2LD in more than 20 different autoimmune diseases, Tregs were not expanded at day-5 in IL2LD group, but only at day-15 (median [IQR] fold change from baseline: 1.26 [1.21-1.33] in IL2LD group; 1.01 [0.95-1.05] in placebo group, p < 0.001). At day-5, however, Tregs had acquired an activated phenotype (fold change of CD25 expression in Tregs: 2.17 [1.70-3.55] in IL2LD versus 0.97 [0.86-1.28] in placebo group, p < 0.0001). Regulator/effector T cells ratio remained elevated throughout treatment period in the IL2LD group (p < 0.001). Number of new active brain lesions and of relapses tended to be reduced in IL2LD treated patients, but the difference did not reach significance in this trial not powered to detect clinical efficacy. CONCLUSION: The effect of IL2LD on Tregs in MS patients was modest and delayed, compared to other auto-immune diseases. This, together with findings that Tregs improve remyelination in MS models and recent reports of IL2LD efficacy in amyotrophic lateral sclerosis, warrants larger studies of IL2LD in MS, notably with increased dosages and/or modified modalities of administration. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov: NCT02424396; EU Clinical trials Register: 2014-000088-42.

Traumatic Cerebral Microbleeds in the Subacute Phase Are Practical and Early Predictors of Abnormality of the Normal-Appearing White Matter in the Chronic Phase.

BACKGROUND AND PURPOSE: In the chronic phase after traumatic brain injury, DTI findings reflect WM integrity. DTI interpretation in the subacute phase is less straightforward. Microbleed evaluation with SWI is straightforward in both phases. We evaluated whether the microbleed concentration in the subacute phase is associated with the integrity of normal-appearing WM in the chronic phase. MATERIALS AND METHODS: Sixty of 211 consecutive patients 18 years of age or older admitted to our emergency department ≤24 hours after moderate to severe traumatic brain injury matched the selection criteria. Standardized 3T SWI, DTI, and T1WI were obtained 3 and 26 weeks after traumatic brain injury in 31 patients and 24 healthy volunteers. At baseline, microbleed concentrations were calculated. At follow-up, mean diffusivity (MD) was calculated in the normal-appearing WM in reference to the healthy volunteers (MDz). Through linear regression, we evaluated the relation between microbleed concentration and MDz in predefined structures. RESULTS: In the cerebral hemispheres, MDz at follow-up was independently associated with the microbleed concentration at baseline (left: B = 38.4 [95% CI 7.5-69.3], P = .017; right: B = 26.3 [95% CI 5.7-47.0], P = .014). No such relation was demonstrated in the central brain. MDz in the corpus callosum was independently associated with the microbleed concentration in the structures connected by WM tracts running through the corpus callosum (B = 20.0 [95% CI 24.8-75.2], P < .000). MDz in the central brain was independently associated with the microbleed concentration in the cerebral hemispheres (B = 25.7 [95% CI 3.9-47.5], P = .023). CONCLUSIONS: SWI-assessed microbleeds in the subacute phase are associated with DTI-based WM integrity in the chronic phase. These associations are found both within regions and between functionally connected regions.

[Infection associated cerebral vasculitis]. / Vascularites cérébrales associées aux infections.

Infections are a frequent cause of cerebral vasculitis, important to diagnose because a specific treatment may be required. Infection-associated vasculitis can be caused by angiotropic pathogens (varicella zoster virus, syphilis, aspergillus). They can be associated with subarachnoidal meningitis (tuberculosis, pyogenic meningitis, cysticercosis). They can appear contiguously to sinuses or orbital infection (aspergillosis, mucormycosis). Finally, they also may be due to an immune mechanism in the context of chronic infections (hepatitis B virus, hepatitis C virus, human immunodeficiency virus). Cerebral vasculitis are severe conditions and their prognosis is directly linked to early recognition and diagnosis. Infectious causes must therefore be systematically considered ahead of cerebral vasculitis, and the appropriate investigations must be determined according to the patient's clinical context. We propose here an update on the infectious causes of cerebral vasculitis, their diagnosis modalities, and therapeutic options.

MRI features of intra-axial histiocytic brain mass lesions.

AIM: To describe MRI features, including diffusion-weighted imaging (DWI), magnetic resonance spectroscopy (MRS), and perfusion-weighted imaging (PWI), of intra-axial tumour-like presentations of four different subtypes of histiocytosis. MATERIAL AND METHODS: The brain MRI findings of 23 patients with histologically proven histiocytosis were reviewed retrospectively (11 Langerhans cell histiocytosis [LCH], eight Erdheim-Chester disease [ECD], one overlap form LCH/ECD, two Rosai-Dorfman disease [RDD], and one haemophagocytic lymphohistiocytosis [HLH]) with single or multiple enhancing intraparenchymal brain lesions. RESULTS: Histiocytic brain mass lesions show some similar MRI features including Supra and/or infratentorial and/or paraventricular subcortical well-delineated masses, linear ependymal enhancement along the ventricles and brain stem lesions. Masses always present with mixed hyper- and hypointense signal on T2-weighted imaging (WI). Their enhancement is often homogeneous. Apparent diffusion coefficient (ADC) values are often normal or elevated. CONCLUSION: The presence of multiple periventricular and subcortical enhancing lesions with mixed signal intensity on T2WI and normal or high ADC values should lead radiologists to consider the diagnosis of histiocytic lesions and search for associated systemic lesions.

Clinical, imaging and follow-up study of optic neuritis associated with myelin oligodendrocyte glycoprotein antibody: a multicentre study of 62 adult patients.

BACKGROUND AND PURPOSE: There are few clinico-radiological data on optic neuritis (ON) with myelin oligodendrocyte glycoprotein antibody (MOG-IgG). The objective was to characterize the clinico-radiological phenotype and outcome of patients with MOG-IgG-related ON. METHODS: The records of all adult patients admitted in three medical centres with MOG-IgG-associated ON who underwent orbital and brain magnetic resonance imaging (MRI) at the acute phase were reviewed. Spinal cord MRI within 1 month from the ON and all of the follow-up MRI were reviewed. RESULTS: Of 62 patients, 41.9% had bilateral ON and 66.2% optic disc swelling. On initial MRI, lesions were anterior (92%), extensive (63%) and associated with optic perineuritis (46.6%). Silent brain lesions were found in 51.8% of patients but were mainly non-specific (81%). Of 39 individuals with spinal MRI at onset, nine had abnormal findings (four were asymptomatic). Two symptomatic patients had longitudinally extensive myelitis with concurrent H-sign. At last follow-up, 5% of patients had visual acuity ≤0.1. Brain MRI remained unchanged in 41 patients (87%). CONCLUSIONS: Our study supports a mostly benign ophthalmological course of MOG-IgG-associated ON, despite initially longitudinally extensive lesions and development of optic nerve atrophy on orbital MRI. Spinal MRI could be of interest in detecting silent suggestive lesions.

Characterization of Skull Base Lesions Using Pseudo-Continuous Arterial Spin Labeling.

PURPOSE: Pseudo-continuous arterial spin labeling (pCASL) is a non-invasive magnetic resonance (MR) perfusion technique. Our study aimed at estimating the diagnostic performance of the pCASL sequence in assessing the perfusion of skull base lesions both qualitatively and quantitatively and at providing cut-off values for differentiation of specific skull base lesions. METHODS: In this study 99 patients with histopathologically confirmed skull base lesions were retrospectively enrolled. Based on a pathological analysis, the lesions were classified as hypervascular and non-hypervascular. Patients were divided into two subgroups according to the anatomical origin of each lesion. The MRI study included pCASL and 3D T1-weighted fat-saturated post-contrast sequences. Of the patients seven were excluded due to technical difficulties or patient movement. The lesions were classified by two raters, blinded to the diagnosis as either hyperperfused or non-hyperperfused, based on the pCASL sequence. The normalized tumor blood flow (nTBF) of each lesion was determined. Qualitative and quantitative characteristics of hypervascular and non-hypervascular lesions were compared. RESULTS: Visual assessment enabled correct classification of 98% of the lesions to be performed. Quantitatively, we found significant differences between the nTBF values for hypervascular and non-hypervascular lesions (p < 0.001) and provided cut-off values, allowing meningioma and schwannoma to be distinguished from meningioma and adenoma. Significant differences were also found within the hypervascular group, namely, paraganglioma was more hyperperfused than meningioma (p = 0.003) or metastases (p = 0.009). CONCLUSION: The present study demonstrates the high diagnostic performance of pCASL in characterizing skull base lesions by either visual assessment or nTBF quantification. Adding the pCASL sequence to the conventional protocol of skull base assessment can be recommended.

Capecitabine-induced acute toxic leukoencephalopathy.

A 45-year-old woman was treated by Capecitabine (Xeloda®) during 6days for breast cancer with metastatic bone lesions when she presented with nausea, headaches, muscle cramps, dysarthria and swallowing disorders. A stroke was first suspected. Brain CT was normal. MRI showed bilateral and symmetric high signal intensities of deep white matter, corpus callosum and corticospinal tracts on diffusion-weighted imaging and T2 fluid-attenuated inversion recovery (FLAIR) sequence, similar to 5-FU acute leukoencephalopathy. An acute toxic leukoencephalopathy was diagnosed prompting to discontinue capecitabine, which allowed a regression of the symptoms. Though acute toxic leukoencephalopathies with pseudo-stroke presentation have been reported with other chemotherapy agents such as methotrexate or 5-fluorouracil (5-FU), cases of leukoencephalopathy induced by capecitabine are less reported and less well known. This oral precursor of 5-FU is commonly used to treat colorectal, stomach or breast cancers. Neurotoxicity of other 5-FU derivates like cormafur and tergafur have rarely been depicted as well. Although 5-FU-induced leukoencephalopathy is known, the potential toxicity of its precursor should be acknowledged as well. Early detection of chemotherapy-induced toxicity by MRI is crucial as symptoms may be reversible to the condition that chemotherapy is immediately discontinued.

[Neurosarcoidosis: Diagnosis and therapeutic issues]. / Les atteintes neurologiques au cours de la sarcoïdose : diagnostic et traitement.

Neurological localizations of sarcoidosis are heterogeneous and may affect virtually every part of the central or peripheral nervous system. They are often the inaugural manifestation of sarcoidosis. The diagnosis may be difficult due to the lack of extra-neurological localization. Diagnosis may be discussed in the presence of an inflammatory neurological disease, in particular in case of suggestive radiological or biological pattern. Cerebrospinal fluid analysis shows lymphocytic pleiocytosis, often with low glucose level. The diagnosis relies on a clinical, biological and radiological presentation consistent with neurosarcoidosis, the presence of non-caseating granuloma and exclusion of differential diagnoses. Screening for other localizations of sarcoidosis, in particular cardiac disease may be obtained during neurosarcoidosis. The treatment of neurosarcoidosis relies on corticosteroids although immunosuppressive drugs are usually added because of the chronic course of this condition and to limit the side effects of steroids. Treatments and follow-up may be prolonged because of the high rate of relapses.

Pseudo-asymmetry of cerebral blood flow in arterial spin labeling caused by unilateral fetal-type circle of Willis: Technical limitation or a way to better understanding physiological variations of cerebral perfusion and improving arterial spin labeling acquisition?

In the recently published article, "Unilateral fetal-type circle of Willis anatomy causes right-left asymmetry in cerebral blood flow with pseudo-continuous arterial spin labeling: A limitation of arterial spin labeling-based cerebral blood flow measurements?", it was shown by the method of arterial spin labeling (ASL) that unilateral fetal-type circle of Willis could induce variation of blood flow in cerebellar and posterior cerebral artery territory. We believe that the reported observation, rather than being a limitation, gives several interesting cues for understanding the ASL sequence. In this commentary, we formulate some suggestions regarding the use of ASL in clinical practice, discuss the potential causes of the above-mentioned pseudo-asymmetry and consider future improvements of the ASL technique.

Deafferentation in thalamic and pontine areas in severe traumatic brain injury.

PURPOSE: Severe traumatic brain injury (TBI) is characterized mainly by diffuse axonal injuries (DAI). The cortico-subcortical disconnections induced by such fiber disruption play a central role in consciousness recovery. We hypothesized that these cortico-subcortical deafferentations inferred from diffusion MRI data could differentiate between TBI patients with favorable or unfavorable (death, vegetative state, or minimally conscious state) outcome one year after injury. METHODS: Cortico-subcortical fiber density maps were derived by using probabilistic tractography from diffusion tensor imaging data acquired in 24 severe TBI patients and 9 healthy controls. These maps were compared between patients and controls as well as between patients with favorable (FO) and unfavorable (UFO) 1-year outcome to identify the thalamo-cortical and ponto-thalamo-cortical pathways involved in the maintenance of consciousness. RESULTS: Thalamo-cortical and ponto-thalamo-cortical fiber density was significantly lower in TBI patients than in healthy controls. Comparing FO and UFO TBI patients showed thalamo-cortical deafferentation associated with unfavorable outcome for projections from ventral posterior and intermediate thalamic nuclei to the associative frontal, sensorimotor and associative temporal cortices. Specific ponto-thalamic deafferentation in projections from the upper dorsal pons (including the reticular formation) was also associated with unfavorable outcome. CONCLUSION: Fiber density of cortico-subcortical pathways as measured from diffusion MRI tractography is a relevant candidate biomarker for early prediction of one-year favorable outcome in severe TBI.

Cerebral tumor or pseudotumor?

Pseudotumoral lesions are uncommon but important to identity lesions. They can occur during inflammatory diseases (systemic diseases, vasculitis, demyelinating diseases), infectious, and vascular diseases. Also, in a patient with a treated tumor, pseudo-progression and radionecrosis must be differentiated from the tumoral development. Diagnosis can be difficult on an MRI scan, but some MRI aspects in conventional sequences, diffusion, perfusion and spectroscopy can suggest the pseudotumoral origin of a lesion. Imaging must be interpreted according to the context, the clinic and the biology. The presence of associated intracranial lesions can orientate towards a systemic or infectious disease. A T2 hyposignal lesion suggests granulomatosis or histiocytosis, especially if a meningeal or hypothalamic-pituitary involvement is associated. Non-tumoral lesions are generally not hyperperfused. In the absence of a definitive diagnosis, the evolution of these lesions, whether under treatment or spontaneous, is fundamental.

Long-term white matter changes after severe traumatic brain injury: a 5-year prospective cohort.

BACKGROUND AND PURPOSE: Extensive white matter damage has been documented in patients with severe traumatic brain injury, yet how this damage evolves in the long term is not well understood. We used DTI to study white matter changes at 5 years after traumatic brain injury. MATERIALS AND METHODS: There were 8 healthy control participants and 13 patients with severe traumatic brain injury who were enrolled in a prospective observational study, which included clinical assessment and brain MR imaging in the acute setting (< 6 weeks) and 2 years and 5 years after injury. Only subjects with mild to moderate disability or no disability at 1 year were included in this analysis. DTI parameters were measured in 20 different brain regions and were normalized to values obtained in an age-matched control group. RESULTS: In the acute setting, fractional anisotropy was significantly lower in the genu and body of the corpus callosum and in the bilateral corona radiata in patients compared with control participants, whereas radial diffusivity was significantly (P < .05) higher in these tracts. At 2 years, fractional anisotropy in these tracts had further decreased and radial diffusivity had increased. No significant changes were detected between 2 and 5 years after injury. The baseline radial diffusivity and fractional anisotropy values in the anterior aspect of the brain stem, genu and body of the corpus callosum, and the right and left corona radiata were significantly (P < .05) associated with neurocognitive sequelae (including amnesia, aphasia, and dyspraxia) at year 5. CONCLUSIONS: DTI changes in major white matter tracts persist up to 5 years after severe traumatic brain injury and are most pronounced in the corpus callosum and corona radiata. Limited structural change is noted in the interval between 2 and 5 years.

Imaging of the optic chiasm and retrochiasmal visual pathways.

The exploration of the chiasmal and retrochiasmal visual pathways is based on magnetic resonance imaging. A bitemporal hemianopsis suggests a lesion of the optic chiasm while homonymous lateral hemianopsis should lead to a search for a lesion of the retrochiasmal visual pathways. The causes of chiasmal impairment are mainly tumoral. The exploration protocol is based on MRI with T1-weighted sagittal sections, then T2- and T1-weighted coronal sections with and without injection. In case of a retrochiasmal syndrome, the MRI exploration protocol is a function of the type of occurrence of the deficiency and the context.

Imaging findings of intraventricular and ependymal lesions.

Intraventricular and ependymal lesions comprise a wide spectrum of tumoral, cystic, vascular, infectious and inflammatory disorders. With respect to tumoral and cystic diseases, the location, age and CT and MRI patterns are the main factors for diagnosis. The MRI findings of infectious diseases are supported by the clinical history, immune status and laboratory findings. Intracranial associated lesions may be very helpful for the diagnosis of Sturge-Weber, subependymal giant cell astrocytoma and systemic diseases, such as sarcoidosis and histiocytosis. Intraventricular vascular lesions are rare but present typical features on neuroimaging. The aim of this review is to provide a detailed description of these disorders with an emphasis on the key imaging findings and to generate a narrow differential diagnosis. We present a diagnostic approach based on the solid or cystic aspect of the intraventricular focal mass, its origin from the ventricular wall or choroid plexus and its location within the ventricular system. We also propose a differential diagnosis for ependymal dissemination: the ependymal enhancement may be due to ventriculitis from adjacent parenchymal lesions, the ependymal spread of tumors or infectious or inflammatory/systemic diseases.

[Paraganglioma of the cauda equina region: Report of six cases and review of the literature]. / Paragangliomes de la queue de cheval : à propos de six cas et revue de la littérature.

BACKGROUND AND PURPOSE: Paragangliomas of the cauda equina are rare tumors. The standard treatment is surgical resection. Our study aims to compare our clinical, radiological, prognostic data to the literature and to offer management and follow-up recommendations. METHODS: In this retrospective study, six patients with paraganglioma of the cauda equina region were treated. Symptoms included radicular nerve pain and low back pain with occasional sphincter dysfunction and motor deficit. MRI showed well-circumscribed lesions with homogeneous enhancement following gadolinium injection. Treatment involved complete surgical resection of the tumor under electrophysiological control. In addition to the characteristics of the tumor, we assessed operating results as well as postoperative morbidity and follow-up. RESULTS: All patients had complete removal of the tumor, which required in most cases the resection of the carrying root. The intervention allowed a regression of the initial symptoms, with possible postoperative regressive sphincter disorders. Clinical and radiological follow-up (19 months on average), showed no tumor recurrence. CONCLUSIONS: The reference treatment of these tumors is complete surgical resection, usually requiring the sacrifice of the carrying nerve root. Intra-operative nerve roots stimulation is recommended to reduce the risk of motor deficit linked to this radical treatment. A long-term clinical and radiological follow-up is recommended.

Probing consciousness with event-related potentials in the vegetative state.

OBJECTIVE: Probing consciousness in noncommunicating patients is a major medical and neuroscientific challenge. While standardized and expert behavioral assessment of patients constitutes a mandatory step, this clinical evaluation stage is often difficult and doubtful, and calls for complementary measures which may overcome its inherent limitations. Several functional brain imaging methods are currently being developed within this perspective, including fMRI and cognitive event-related potentials (ERPs). We recently designed an original rule extraction ERP test that is positive only in subjects who are conscious of the long-term regularity of auditory stimuli. METHODS: In the present work, we report the results of this test in a population of 22 patients who met clinical criteria for vegetative state. RESULTS: We identified 2 patients showing this neural signature of consciousness. Interestingly, these 2 patients showed unequivocal clinical signs of consciousness within the 3 to 4 days following ERP recording. CONCLUSIONS: Taken together, these results strengthen the relevance of bedside neurophysiological tools to improve diagnosis of consciousness in noncommunicating patients.

A common pattern of brain MRI imaging in mitochondrial diseases with complex I deficiency.

OBJECTIVE: To identify a consistent pattern of brain MRI imaging in primary complex I deficiency. Complex I deficiency, a major cause of respiratory chain dysfunction, accounts for various clinical presentations, including Leigh syndrome. Human complex I comprises seven core subunits encoded by mitochondrial DNA (mtDNA) and 38 core subunits encoded by nuclear DNA (nDNA). Moreover, its assembly requires six known and many unknown assembly factors. To date, no correlation between genotypes and brain MRI phenotypes has been found in complex I deficiencies. DESIGN AND SUBJECTS: The brain MRIs of 30 patients carrying known mutation(s) in genes involved in complex I were retrospectively collected and compared with the brain MRIs of 11 patients carrying known mutations in genes involved in the pyruvate dehydrogenase (PDH) complex as well as 10 patients with MT-TL1 mutations. RESULTS: All complex I deficient patients showed bilateral brainstem lesions (30/30) and 77% (23/30) showed anomalies of the putamen. Supratentorial stroke-like lesions were only observed in complex I deficient patients carrying mtDNA mutations (8/19) and necrotising leucoencephalopathy in patients with nDNA mutations (4/5). Conversely, the isolated stroke-like images observed in patients with MT-TL1 mutations, or the corpus callosum malformations observed in PDH deficient patients, were never observed in complex I deficient patients. CONCLUSION: A common pattern of brain MRI imaging was identified with abnormal signal intensities in brainstem and subtentorial nuclei with lactate peak as a clue of complex I deficiency. Combining clinico-biochemical data with brain imaging may therefore help orient genetic studies in complex I deficiency.