In vivo corneal confocal microscopy (IVCM) allows the immediate analysis of the corneal nerve quantity and morphology. This method became, an indispensable tool for the tropism examination, as it evaluates the small fiber plexus in the cornea. The IVCM provides us with direct information on the health of the sub-basal nerve plexus and indirectly on the peripheral nerve status. It is an important tool used to investigate peripheral polyneuropathies. Small-fiber neuropathy (SFN) is a group of neurological disorders characterized by neuropathic pain symptoms and autonomic complaints due to the selective involvement of thinly myelinated Aδ-fibers and unmyelinated C-fibers. Accurate diagnosis of SFN is important as it provides a basis for etiological work-up and treatment decisions. The diagnosis of SFN is sometimes challenging as the clinical picture can be difficult to interpret and standard electromyography is normal. In cases of suspected SFN, measurement of intraepidermal nerve fiber density through a skin biopsy and/or analysis of quantitative sensory testing can enable diagnosis. The purpose of the present review is to summarize the current knowledge about corneal nerves in different SFN. Specifically, we explore the correlation between nerve density and morphology and type of SFN, disease duration, and follow-up. We will discuss the relationship between cataracts and refractive surgery and iatrogenic dry eye disease. Furthermore, these new paradigms in SFN present an opportunity for neurologists and clinical specialists in the diagnosis and monitoring the peripheral small fiber polyneuropathies.

Granulomatosis with polyangiitis (GPA), formerly known as Wegener’s granulomatosis, is a rare form of necrotizing granulomatous inflammation that predominantly affects medium and small size vessels. Generally respiratory tracts and kidneys are the most affected organs. Neurological manifestations of GPA usually involve the peripheral nervous system causing mononeuritis multiplex or and cranial nerve palsies. Central nervous system (CNS) involvement is rare and characterized by cerebral vasculitis, meningeal inflammation, or mass lesions. The CNS involvement is often linked to Ear Nose Throat (ENT) system disease. In this report, we present two cases of patients diagnosed with GPA who exhibit CNS involvement as first symptom. In the first one with an ischemic stroke while in the second with an atypical headache. In the first patient, a positive medical history indicating involvement of the Ear, Nose, and Throat (ENT) facilitated a precise diagnosis through the prompt execution of autoimmune screening. This, in turn, enabled a timely commencement of treatment, resulting in neurological improvement. In the second case, the significance of ENT involvement was initially overlooked in the context of pathological definition, leading to a substantial delay in diagnosis and an ultimately grim prognosis for the patient. The ENT involvement could be an easy marker to suspect GPA in patient with atypical CNS presentation and could help to make a prompt diagnosis.