Predictive value of magnetic resonance for identifying neurovascular compressions in trigeminal neuralgia. / Valor predictivo de la resonancia magnética para la identificación de compresiones neurovasculares en la neuralgia del trigémino.

INTRODUCTION: Microvascular decompression (MVD) is accepted as the only aetiological surgical treatment for refractory classic trigeminal neuralgia (TN). There is therefore increasing interest in establishing the diagnostic and prognostic value of identifying neurovascular compressions (NVC) using preoperative high-resolution three-dimensional magnetic resonance (MRI) in patients with classic TN who are candidates for surgery. METHODS: This observational study includes a series of 74 consecutive patients with classic TN treated with MVD. All patients underwent a preoperative three-dimensional high-resolution MRI with DRIVE sequences to diagnose presence of NVC, as well as the degree, cause, and location of compressions. MRI results were analysed by doctors blinded to surgical findings and subsequently compared to those findings. After a minimum follow-up time of six months, we assessed the surgical outcome and graded it on the Barrow Neurological Institute pain intensity score (BNI score). The prognostic value of the preoperative MRI was estimated using binary logistic regression. RESULTS: Preoperative DRIVE MRI sequences showed a sensitivity of 95% and a specificity of 87%, with a 98% positive predictive value and a 70% negative predictive value. Moreover, Cohen's kappa (CK) indicated a good level of agreement between radiological and surgical findings regarding presence of NVC (CK 0.75), type of compression (CK 0.74) and the site of compression (CK 0.72), with only moderate agreement as to the degree of compression (CK 0.48). After a mean follow-up of 29 months (range 6-100 months), 81% of the patients reported pain control with or without medication (BNI score i-iiiI). Patients with an excellent surgical outcome, i.e. without pain and off medication (BNI score i), made up 66% of the total at the end of follow-up. Univariate analysis using binary logistic regression showed that a diagnosis of NVC on the preoperative MRI was a favorable prognostic factor that significantly increased the odds of obtaining an excellent outcome (OR 0.17, 95% CI 0.04-0.72; P=.02) or an acceptable outcome (OR 0.16, 95% CI 0.04-0.68; P=.01) after MVD. CONCLUSIONS: DRIVE MRI shows high sensitivity and specificity for diagnosing NVC in patients with refractory classic TN and who are candidates for MVD. The finding of NVC on preoperative MRI is a good prognostic factor for long-term pain relief with MVD.

Acquired hepatocerebral degeneration: clinical characteristics and MRI findings.

OBJECTIVE: To determine the prevalence of acquired hepatocerebral degeneration (AHD), its clinical and neuroimaging characteristics and response to treatments. BACKGROUND: Acquired hepatocerebral degeneration is a chronic encephalopathy with predominant motor signs in the context of severe liver disease. Its clinical picture is not well defined, and its prevalence and risk factors are not well known. METHODS: Review of a database of 1000 patients with cirrhosis to identify cases of AHD. Clinical and neuroimaging data, follow-up and response to treatments, including liver transplantation, were recorded. RESULTS: Eight patients with AHD were identified. Its prevalence was 0.8% of patients with cirrhosis. The main risk factor for AHD was the presence of portosystemic shunts. Movement disorders, especially a combination of parkinsonism and cerebellar signs were observed in all patients. All AHD cases showed on MRI T1-weighted images hyperintensities in the globus pallidus, and 75% had extrapallidal involvement as well. Antiparkisonian drugs and treatments to prevent acute encephalopathies were ineffective. Three patients who underwent liver transplantation did not experience neurological improvement. Persistence of portosystemic shunts was demonstrated in two cases. CONCLUSIONS: Acquired hepatocerebral degeneration is a chronic encephalopathy which occurs in ∼1% of patients with liver cirrhosis and seems related to portosystemic shunts. Its is characterized by a combination of parkinsonism and cerebellar signs. MRI pallidal and extrapallidal lesions are seen in most patients, probably reflecting intracerebral deposits of manganese. Liver transplant did not improve the neurological signs in our patients, perhaps because of the persistence of portosystemic shunts.

In vitro study of magnetic resonance imaging artefacts of six supraglottic airway devices.

We investigated the artefacts created during magnetic resonance imaging by five different laryngeal mask airways: the Classic (cLMA); the LMA ProSeal; the LMA Unique; the Ambu Disposable Laryngeal Mask; the LMA Supreme; and one other supraglottic airway device, the i-gel supraglottic airway. The devices were placed on top of and inside a phantom simulator to resemble the position in vivo. The artefacts with the cLMA, Unique and Supreme were similar and related to ferromagnetic material in the pilot balloon valve. Artefacts were more prominent with the ProSeal. There were no artefacts with the Ambu Disposable Laryngeal Mask or the i-gel.