Difference between revisions of "6° Clinical case: Facial onset sensory and motor neuronopathy"

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File:FOSMN3.jpeg|'''Article 3:''' This article is superimposable on our pre-diagnosis and reports signs and symptoms very similar to our patient, so it is considered as corresponding information and therefore a path to follow. The next step, therefore, will concern the 'Sensory and motor neuronopathy with facial onset' initialed as 'FOSMN'.

Trigeminal motor evoked potentials were tested by transcranial magnetic stimulation,<ref>Cruccu G, Berardelli A, Inghilleri M, Manfredi M. Functional organization of the trigeminal motor system in man. A neurophysiological study. Brain. 1989;112:1333–1350. doi: 10.1093/brain/112.5.1333.</ref> the temporal H reflex, evaluating the Aα fiber (Ia fiber) in the monosynaptic trigeminal reflex,<ref>Cruccu G, Truini A, Priori A. Excitability of the human trigeminal motoneuronal pool and interactions with other brainstem reflex pathways. J Physiol. 2001;531:559–571. doi: 10.1111/j.1469-7793.2001.0559i.x.</ref> the early components of the blink reflex (R1) after electrical stimulation of the supraorbital nerve, and the masseter inhibitory reflex (SP1) after stimulation of the mental nerve, assessing the fibers <math>A\beta</math>.<ref>Valls-Solé J. Neurophysiological assessment of trigeminal nerve reflexes in disorders of central and peripheral nervous system. Clin Neurophysiol. 2005;116:2255–2265. doi: 10.1016/j.clinph.2005.04.020.</ref> Laser-evoked potentials (LEP) were also recorded to study nociceptors <math>A\delta</math>(<math>A\delta</math>-LEP) and unmyelinated fiber heat receptors (C-LEP).<ref>Cruccu G, Pennisi E, Truini A, Iannetti GD, Romaniello A, Le Pera D, De Armas L, Leandri M, Manfredi M, Valeriani M. Unmyelinated trigeminal pathways as assessed by laser stimuli in humans. Brain. 2003;126:2246–2256. doi: 10.1093/brain/awg227.</ref> The neurophysiological tests have adhered to the technical requirements issued by the International Federation of Clinical Neurophysiology.<ref>Kimura J, editor. Peripheral Nerve Diseases, Handbook of Clinical Neurophysiology.Amsterdam: Elsevier; 2006.</ref><ref>Cruccu G, Aminoff MJ, Curio G, Guerit JM, Kakigi R, Mauguiere F, Rossini PM, Treede RD, Garcia-Larrea L. Recommendations for the clinical use of somatosensory-evoked potentials. Clin Neurophysiol. 2008;119:1705–1719. doi: 10.1016/j.clinph.2008.03.016.</ref>

From the study by Cruccu et al.<ref name=":0">Cruccu G, Pennisi EM, Antonini G, Biasiotta A, di Stefano G, La Cesa S, Leone C, Raffa S, Sommer C, Truini A.Trigeminal isolated '''sensory''' neuropathy (TISN) and FOSMN syndrome: despite a dissimilar disease course do they share common pathophysiological mechanisms? BMC Neurol. 2014 Dec 19;14:248. doi: 10.1186/s12883-014-0248-2.PMID: 25527047 </ref> first of all it is deduced that despite detailed neurophysiological and morphometric investigations, no clinical, neurophysiological or neuropathological differences can be found between TISN and FOSMN, therefore, the two diseases could be pathophysiologically similar neuropathies of the type of dissociated neuropathies that completely spare the unmyelinated fibers as demonstrated by the biopsy exam. Light and electron microscopy in supraorbital nerve biopsy specimens from patients with TISN and those with FOSMN have shown variously severe axonal myelinated fiber loss, as others have reported in these patients.<ref>Lecky BR, Hughes RA, Murray NM. Trigeminal sensory neuropathy. A study of 22 cases. Brain. 1987;110:1463–1485. doi: 10.1093/brain/110.6.1463. </ref><ref name=":1">Vucic S, Tian D, Chong PS, Cudkowicz ME, Hedley-Whyte ET, Cros D. Facial onset sensory and motor neuronopathy (FOSMN syndrome): a novel syndrome in neurology. Brain. 2006;129:3384–3390. doi: 10.1093/brain/awl258.</ref> We extend these findings by providing quantitative data showing that trigeminal neuropathy affects fibers <math>A\beta</math> more severely than fibers<math>A\delta</math>. Evidence that nerve fiber damage progresses from the largest to the smallest fiber also comes from neurophysiological findings, which invariably show responses mediated by the impaired fiber <math>A\beta</math> even in the early stages of the disease. In contrast, <math>A\delta</math> fiber-mediated responses were much less impaired.