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

== Abstract ==

{{ArtBy|

}}

In this section of Masticationpedia 'Are we sure to know everything?​​' we present two emblematic clinical cases that demonstrate the complexity and contextually the difficulty in making a differential diagnosis between Orofacial disorders and serious organic pathologies. These diagnostic difficulties and limits do not only concern the operator's clinical ability, rather the operator's forma mentis too concentrated on pre-established axioms and dogmas. We have already mentioned the ambiguity and vagueness of verbal language logic but we should also be self-critical about established dogmas such as RDC/TMD protocols, P-value,<ref>S Catarzi, D Morrone, D Ambrogetti, P Bravetti, M Rosselli Del Turco, S Ciatto[Errors in mammography. II. False positives] Radiol Med. 1992 Mar;83(3):201-5.

</ref>

Patient who came to our attention from the Gastroenterology department due to a state of organic food wasting that was difficult to explain in the gastrointestinal diseases. The young patient (aged 40) to whom we give our usual invented name 'Flora' (name of the goddess of flowers in ancient Rome) had undergone maxillofacial surgery for a unilateral crossbite 5 years before she reached our attention. 'Flora' had never had any sensitivity disorder but only an aesthetic problem in smiling and minor masticatory problems such as to turn to a maxillofacial surgeon. The surgery consisted of a rapid surgical palate expansion but after an unquantified period of time there was a recurrence and at the same time slight forms of facial tingling especially in the upper perioral area together with an unexplained gingival recession of the right maxillary dental arch. A few months later, small skin vesicles began to form in her right perioral area, interpreted at the time as a vasculitis manifestation. (Figure 1) Our Flora obviously worried about these consequences relied on dental care both for gum recessions but also for psychological support given the relapses resolved palliatively with a biteplane with the intention of managing night-time stress. Over a period of another 10 months, the patient worried about the conspicuous worsening of her psychophysical conditions and excessive weight loss, decided to refer to a gastroenteric expert who excluded any gastrointestinal pathological form or attributable to malabsorption. (Figure 2) The gastroenterologist colleague had the intuition that perhaps the clinical manifestations of the patient Flora could be attributable to a masticatory difficulty and reported it to our 'Neurognathology' Centre.  

From what emerges from the neurological statements, the 'State' of the Trigeminal Nervous System appears unstructured, highlighting anomalies of the trigeminal reflexes, therefore, the 'Initialization' command is the '[https://pubmed.ncbi.nlm.nih.gov/?term=Trigeminal+system+&filter=datesearch.y_10&size=200 Trigeminal System]'to go and test the database (Pubmed).  

[[File:FOSMN.jpeg|border|right|500x500px]]

*'''2^st loop open:''' The  [https://pubmed.ncbi.nlm.nih.gov/?term=Trigeminal+system+AND+sensory&filter=datesearch.y_10&size=200 'Sensory]' key returns 666 articles on which to do cognitive brainstorming and that is to think about which other element should be inserted in order not to deviate the search from the pre-established set. For example, if in this stage we had entered the term 'jaw jerk' (which has emerged as a decisive test for the diagnosis) the network returns only one article (Differential Diagnosis of Chronic Neuropathic Orofacial Pain: Role of Clinical Neurophysiology). This article concerns a series of tests that can be used for the differential diagnosis in neuropathies but does not help us in researching the type of structural damage the patient is affected by. For this reason it is best to stick to a broad perspective of generic information such as 'Reflexes'.

*

*

<Center>

</gallery>  

</Center>

*

*

*

*

*

The patient 'Flora' was, therefore, immediately referred to the trigeminal neurophysiology departments with a pre-diagnosis of 'Electrodiagnostic findings in facial onset sensory motor neuronopathy (FOSMN)' and we report the procedure that confirmed the diagnosis to make it more the diagnostic path that a clinical dentist should follow in such rare but dramatically serious cases is explanatory. In fact, the diagnosis is not linear in the first cases because the symptoms could be superimposed on various physiopathogenetic phenomena such as temporomandibular disorders (TMDs), trigeminal neuralgia (TN), forms of trigeminal neuropathies such as 'isolated sensory trigeminal neuropathy' (TISN ) and that identified in this clinical case 'Facial onset sensory and motor neuronopathy' (FOSMN). This diagnostic process is required because in the case of TISN or FOSMN the prognosis is often poor.  

In Prof. Cruccu's Department of Neurology and Clinical Neurophysiology, the patient underwent the following tests:

Trigeminal and extra-trigeminal sensory function were assessed: touch was studied with a cotton ball, vibration with a tuning fork (128 Hz), and pin-prick sensation with a wooden cocktail stick. Gait impairment and muscle strength were assessed with the Medical Research Council score. We were also asked to report dysautonomic symptoms. The patient underwent laboratory tests, including tests to rule out identifiable causes of trigeminal neuropathy: autoantibody assays to detect connective tissue disease (antinuclear antibodies, anti-double stranded DNA, antinuclear extractable antigens, including anti Sm, anti RNP, anti Scl70 and anti -phospholipids, antineutrophil cytoplasmic antibodies and anti Ro/SSA and anti-La/SSB for Sjögren's disease).

Semithin sections were stained with toluidine blue for light microscopic evaluation. Ultrathin sections from tissue blocks in the correct orientation, post-stained with uranyl acetate and lead hydroxide, were examined with a Morgagni 268D transmission electron microscope (FEI, Hillsboro, OR, USA). Digital images were analyzed with AnalySIS software (SIS) and all myelinated and unmyelinated structures were identified and measured. Fiber densities were calculated and expressed as average number of fibers/mm².

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:[tel:2255–2265 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:[tel:2246–2256 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>

Motor evoked potentials from transcranial magnetic stimulation and the temporalis muscle H reflex yielded normal results; in contrast, reflex recordings showed severe abnormalities: the first response to become absent bilaterally was the early masseter inhibitory reflex (ES1) after mental nerve stimulation and the early blink reflex (R1). While <math>A\delta</math> fiber-mediated LEPs were often abnormal (but less impaired than early trigeminal reflexes), unmyelinated C-fiber-mediated C-LEPs were normal. These patterns of neurophysiological abnormalities generally suggested that the disease progressed from larger to smaller afferent fibers. <blockquote>The one notable exception was the normal temporal H reflex afferent-mediated by <math>A\alpha</math>. Both light and electron microscopy showed only Wallerian-like degeneration involving myelinated fibers, more severe for the large <math>A\beta</math> and small group <math>A\delta</math>, with no inflammatory changes.</blockquote>

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:[tel:3384–3390 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.