Facial onset sensory and motor neuronopathy (FOSMN syndrome): a novel syndrome in neurology

Abstract

A 'syringomyelia-like' syndrome has been infrequently reported in neurological disorders such as Tangiers disease and lepromatous leprosy. This study reports a novel 'syringomyelia-like' syndrome in four adult male patients, which we have termed facial onset sensory and motor neuronopathy, or FOSMN syndrome, that appears to have a neurodegenerative aetiology. Clinical, neurophysiological and pathological data of four patients were reviewed, including the autopsy in one patient. Four male patients (mean age at onset 43), initially developed paraesthesiae and numbness in a trigeminal nerve distribution, which slowly progressed to involve the scalp, neck, upper trunk and upper limbs in sequential order. Motor manifestations, including cramps, fasciculations, dysphagia, dysarthria, muscle weakness and atrophy developed later in the course of the illness. Neurophysiological findings revealed a generalized sensory motor neuronopathy of caudally decreasing severity in all four patients. Autopsy in one patient disclosed loss of motoneurons in the hypoglossal nucleus and cervical anterior horns, along with loss of sensory neurons in the main trigeminal sensory nucleus and dorsal root ganglia. FOSMN syndrome appears to be a slowly progressive neurodegenerative disorder, whose pathogenesis remains to be determined.

Facial onset sensory and motor neuronopathy (FOSMN) syndrome responding to immunotherapies

“…A neurodegenerative process was proposed because of the absence of inflammatory cell infiltrates in the nervous tissues and the lack of response to various immunotherapies [1]. In the present case, however, the responses to immunotherapies supported a contribution from an immunological mechanism resembling CIDP [11].…”

“…In 2006, Vucic et al [1] reported a novel syndrome named FOSMN syndrome in four Caucasian men in their 40s. They suggested neuronopathy, because of reduced SNAP and CMAP amplitudes together with the widespread occurrence of denervation potentials in bulbar and limb muscles.…”

“…Facial onset sensory and motor neuronopathy (FOSMN syndrome) is a recently described, unusual condition in Caucasians that presents with facial onset sensory abnormalities spreading to the scalp, upper trunk and extremities, and is followed by lower motor neuron deficits [1]. A neurodegenerative process has been hypothesized, but not yet proven.…”

Recognising facial onset sensory motor neuronopathy syndrome: insight from six new cases

“…Facial onset sensory and motor neuronopathy (FOSMN) was first described by Vucic et al in 2006;1 there have been 30 cases reported to date 1 2. Its cardinal features are onset with asymmetrical facial numbness or paraesthesia, with impaired light touch and pain sensation evolving in a mantle distribution, followed by bulbar symptoms with facial atrophy and weakness.…”

Differential trigeminal myelinated and unmyelinated nerve fiber involvement in FOSMN syndrome

“…1,2 Although a previous study assessed infraorbital nerve pathology in one patient, 2 no studies have directly aimed at investigating trigeminal nerve fiber damage in patients with FOSMN and assessing the involvement of the different sensory nerve fiber populations in this disease. Having this information might help understand the pathophysiology of FOSMN and thus guide its clinical management.…”