CANVAS, a sensory neuronopathy to look for in ataxia.

Sensory neuronopathies name the degeneration of peripheral sensory neurons in dorsal root ganglia. Among the genetic causes, CANVAS could be the most frequent. CANVAS is a clinical entity associating cerebellar ataxia, sensory neuronopathy and vestibular areflexia due to biallelic expansions in RFC1. This study reports the 18 individuals with sensory neuronopathy tested for RFC1 expansion in our center. The clinical picture showed that chronic cough was a frequent sign beginning before the onset of other symptoms. CANVAS is an underestimated cause of late-onset sensory and cerebellar ataxia that needs to be tested for widely now that the molecular cause is known.

Prospective study of the additional benefit of plexus magnetic resonance imaging in the diagnosis of chronic inflammatory demyelinating polyneuropathy.

BACKGROUND AND PURPOSE: Hypertrophy/signal hyperintensity and/or gadolinium enhancement of plexus structures on magnetic resonance imaging (MRI) are observed in two-thirds of cases of typical chronic inflammatory demyelinating polyneuropathy (CIDP). The objective of our study was to determine the additional benefit of plexus MRI in patients referred to tertiary centers with baseline clinical and electrophysiological characteristics suggestive of typical or atypical CIDP. METHODS: A total of 28 consecutive patients with initial suspicion of CIDP were recruited in nine centers and followed for 2 years. Plexus MRI data from the initial assessment were reviewed centrally. Physicians blinded to the plexus MRI findings established the final diagnosis (CIDP or neuropathy of another cause). The proportion of patients with abnormal MRI was analyzed in each group. RESULTS: Chronic inflammatory demyelinating polyneuropathy was confirmed in 14 patients (50%), as were sensorimotor CIDP (n = 6), chronic immune sensory polyradiculoneuropathy (n = 2), motor CIDP (n = 1) and multifocal acquired demyelinating sensory and motor neuropathy (n = 5). A total of 37 plexus MRIs were performed (17 brachial, 19 lumbosacral and 8 in both localizations). MRI was abnormal in 5/37 patients (14%), all of whom were subsequently diagnosed with CIDP [5/14(36%)], after an atypical baseline presentation. With plexus MRI results masked, non-invasive procedures confirmed the diagnosis of CIDP in all but one patient [1/14 (7%)]. Knowledge of the abnormal MRI findings in the latter could have prevented nerve biopsy being performed. CONCLUSION: Systematic plexus MRI in patients with initially suspected CIDP provides little additional benefit in confirming the diagnosis of CIDP.

[Small fiber neuropathy]. / La neuropathie des petites fibres.

Small fiber neuropathy (SFN) is still unknown. Characterised by neuropathic pain, it typically begins by burning feet, but could take many other expression. SFN affects the thinly myelinated Aδ and unmyelinated C-fibers, by an inherited or acquired mechanism, which could lead to paresthesia, thermoalgic disorder or autonomic dysfunction. Recent studies suggest the preponderant role of ion channels such as Nav1.7. Furthermore, erythromelalgia or burning mouth syndrome are now recognized as real SFN. Various aetiologies of SFN are described. It could be isolated or associated with diabetes, impaired glucose metabolism, vitamin deficiency, alcohol, auto-immune disease, sarcoidosis etc. Several mutations have recently been identified, like Nav1.7 channel leading to channelopathies. Diagnostic management is based primarily on clinical examination and demonstration of small fiber dysfunction. Laser evoked potentials, Sudoscan®, cutaneous biopsy are the main test, but had a difficult access. Treatment is based on multidisciplinary management, combining symptomatic treatment, psychological management and treatment of an associated etiology.

[Stiff-person syndrome and other neurological disorders associated with anti-GAD antibodies]. / Le syndrome de l'homme raide et autres maladies neurologiques associées aux anticorps anti-GAD.

Autoantibodies to glutamic acid decarboxylase (GAD), originally identified in the stiff-person syndrome, are also associated with rare cases of therapy-resistant epilepsy and sporadic cerebellar ataxia. The association of GAD antibodies with these three syndromes and other auto-immune diseases, particularly type 1 diabetes mellitus, argues for their auto-immune origin. Anti-GAD antibodies inhibit GABAergic circuits inducing a neuronal hyper-excitability that seems to be responsible for these three syndromes. However, an additional mechanism seems to be involved in the degenerative component of the cerebellar ataxia associated with anti-GAD antibodies. A more accurate diagnosis and the study of neuropathological cases are necessary to document the different mechanisms implicated in these neurological disorders.

[Psychiatric presentation of human African trypanosomiasis: overview of diagnostic pitfalls, interest of difluoromethylornithine treatment and contribution of magnetic resonance imaging]. / Forme psychiatrique de trypanosomiase africaine: illustration des difficultés diagnostiques et apport de l'imagerie par résonance magnétique.

We report a case of a western African man, residing in France for 4 years, who developed human African trypanosomiasis (HAT) caused by Trypanosoma brucei gambiense. Diagnosis was made at a late stage of the disease. The disease was misdiagnosed and untreated for several years because the clinical presentation was limited to psychiatric disorders and biological confirmation was difficult. Polysomnographic recordings demonstrated typical alterations of HAT. Difluoromethylornithine was effective in this late stage of the disease. Magnetic resonance imaging showed brain edema with demyelination and associated brain atrophy and abnormal signals in the brainstem and thalamus, both implied in sleep-wake cycle.