Prions cause lethal neurodegenerative diseases in mammals and are composed of multichain assemblies of misfolded host-encoded cellular prion protein (PrP). A common polymorphism at codon 129 of the PrP gene (PRNP), where either methionine (M) or valine (V) is encoded, affects the susceptibility to prion disease, as well as the incubation period¹ and clinical phenotype of prion disease. Human infection with the epizootic prion disease bovine spongiform encephalopathy resulted in variant Creutzfeldt–Jakob disease, which provoked a public health crisis in the United Kingdom and other regions. All definite cases of variant Creutzfeldt–Jakob disease to date have occurred in patients with the MM genotype at PRNP codon 129.¹

Guillain–Barré syndrome (GBS) and its variant, Miller Fisher syndrome (MFS) have several subtypes, together forming a continuous spectrum of discrete and overlapping syndromes. Such is the heterogeneity within this spectrum that many physicians may be surprised to learn that these disorders are related pathophysiologically, and therefore share certain clinical features. These include history of antecedent infection, monophasic disease course and symmetrical cranial or limb weakness. The presence of cerebrospinal fluid albuminocytological dissociation (raised protein, normal cell count), antiganglioside antibodies and neurophysiological evidence of axonal or demyelinating neuropathy also support a diagnosis in many cases, but should not be relied upon. Mimics of GBS and MFS can broadly be divided into those presenting with symmetrical limb weakness and those presenting with brainstem signs. MFS and the pharyngeal-cervical-brachial variant of GBS are frequently mistaken for brainstem stroke, botulism or myasthenia gravis, whereas Bickerstaff's brainstem encephalitis is often diagnosed as Wernicke's encephalopathy. Chameleons or atypical presentations of GBS-related disorders include: paraparetic GBS, bifacial weakness with paraesthesias, acute ataxic neuropathy, acute ophthalmoparesis, acute ptosis and acute mydriasis. Many neurologists may also not be aware that deep tendon reflexes remain present or may even appear brisk in up to 10% of patients with GBS. Correct diagnosis of GBS-related disorders helps to avoid unnecessary investigations and allows early immunotherapy if appropriate.

The pharyngeal-cervical-brachial (PCB) variant of Guillain–Barré syndrome is defined by rapidly progressive oropharyngeal and cervicobrachial weakness associated with areflexia in the upper limbs. Serial nerve conduction studies suggest that PCB represents a localised subtype of Guillain–Barré syndrome characterised by axonal rather than demyelinating neuropathy. Many neurologists are unfamiliar with PCB, which is often misdiagnosed as brainstem stroke, myasthenia gravis or botulism. The presence of additional ophthalmoplegia and ataxia indicates overlap with Fisher syndrome. Half of patients with PCB carry IgG anti-GT1a antibodies which often cross-react with GQ1b, whereas most patients with Fisher syndrome carry IgG anti-GQ1b antibodies which always cross-react with GT1a. Significant overlap between the clinical and serological profiles of these patients supports the view that PCB and Fisher syndrome form a continuous spectrum. In this review, we highlight the clinical features of PCB and outline new diagnostic criteria.

Guillain-Barré syndrome (GBS) is the commonest cause of acquired flaccid paralysis in the world and regarded by many as the prototype for postinfectious autoimmunity. Here the authors consider both infectious and noninfectious triggers of GBS and determine where possible what immunological mechanisms may account for this association. In approximately two-thirds of cases, an infectious trigger is reported in the weeks that lead up to disease onset, indicating that the host's response to infection must play an important role in disease pathogenesis. The most frequently identified bacteria, Campylobacter jejuni, through a process known as molecular mimicry, has been shown to induce cross-reactive anti-ganglioside antibodies, which can lead to the development of axonal-type GBS in some patients. Whether this paradigm can be extended to other infectious organisms or vaccines remains an important area of research and has public health implications. GBS has also been reported rarely in patients with underlying systemic diseases and immunocompromised states and although the exact mechanism is yet to be established, increased susceptibility to known infectious triggers should be considered most likely.

BACKGROUND AND PURPOSE: Intracranial collaterals influence the prognosis of patients treated with intravenous tissue plasminogen activator in acute anterior circulation ischemic stroke. We compared the methods of scoring collaterals on pre-tPA brain CT angiography for predicting functional outcomes in acute anterior circulation ischemic stroke. MATERIALS AND METHODS: Two hundred consecutive patients with acute anterior circulation ischemic stroke treated with IV-tPA during 2010–2012 were included. Two independent neuroradiologists evaluated intracranial collaterals by using the Miteff system, Maas system, the modified Tan scale, and the Alberta Stroke Program Early CT Score 20-point methodology. Good and extremely poor outcomes at 3 months were defined by modified Rankin Scale scores of 0–1 and 5–6 points, respectively. RESULTS: Factors associated with good outcome on univariable analysis were younger age, female sex, hypertension, diabetes mellitus, atrial fibrillation, small infarct core (ASPECTS ≥8), vessel recanalization, lower pre-tPA NIHSS scores, and good collaterals according to Tan methodology, ASPECTS methodology, and Miteff methodology. On multivariable logistic regression, only lower NIHSS scores (OR, 1.186 per point; 95% CI, 1.079–1.302; P = .001), recanalization (OR, 5.599; 95% CI, 1.560–20.010; P = .008), and good collaterals by the Miteff method (OR, 3.341; 95% CI, 1.203–5.099; P = .014) were independent predictors of good outcome. Poor collaterals by the Miteff system (OR, 2.592; 95% CI, 1.113–6.038; P = .027), Maas system (OR, 2.580; 95% CI, 1.075–6.187; P = .034), and ASPECTS method ≤5 points (OR, 2.685; 95% CI, 1.156–6.237; P = .022) were independent predictors of extremely poor outcomes. CONCLUSIONS: Only the Miteff scoring system for intracranial collaterals is reliable for predicting favorable outcome in thrombolyzed acute anterior circulation ischemic stroke. However, poor outcomes can be predicted by most of the existing methods of scoring intracranial collaterals.

Intravenous (IV) tissue plasminogen activator (tPA) remains the only approved therapeutic agent for arterial recanalization in acute ischemic stroke (AIS).¹ Although recanalization of the acutely occluded intracranial artery remains the major aim of IV tPA therapy in patients with AIS, to our knowledge, the relationship between arterial recanalization and stroke recovery has been described in only a few studies.^1,2 Recent studies that have reported recanalization mostly pertain to interventional therapies or a combined IV tPA and interventional approach rather than IV tPA only.^2-4 The information about early recanalization (ER) during the first 2 hours of IV tPA infusion may help physicians identify patients suitable for rescue reperfusion therapies. Some patients with ER may develop reocclusion within the first 24 hours and contribute to wide variations in the rates of favorable outcomes.^5,6 Identifying patients with reocclusion or persistent arterial occlusion (PAO) may help the treating physicians plan the optimal rehabilitative strategies and early prognostication. We evaluated the relationship between arterial patency and the timing of recanalization with functional outcomes at 3 months in patients with AIS treated with IV tPA.