FDG-PET/CT Efforts using functional MRI, single-photon emission CT, and fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET in studying olfactory dysfunction and the role of olfaction in neurodegenerative disorders remain largely investigative and are not generally used in routine evaluations [42-48]. MRA Head There is no relevant literature to support the use of MRA head in the evaluation of the olfactory nerve. MRI Head MRI is the mainstay for directly imaging the olfactory apparatus and is best assessed with MRI orbits, face, and neck MRI rather than MRI head, allowing for assessment of the sinonasal components of the olfactory apparatus while simultaneously evaluating the relevant brain structures that can affect olfaction. US Neck There is no relevant literature to support the use of ultrasound (US) neck in the evaluation of the olfactory nerve. Variant 2: Unilateral isolated weakness of the mastication muscles, paralysis of the mastication muscles, sensory abnormalities of the face and head, facial numbness, or trigeminal neuralgia (trigeminal nerve, CN V). Initial imaging. The trigeminal nerve (CN V) is the largest CN, providing general sensation to the face, part of the scalp, the nasal cavity, oral cavity, and teeth. It also provides branchial motor innervation to the muscles of mastication. The 4 central trigeminal nerve nuclei are located within the brainstem and include the mesencephalic nucleus, the principal sensory nucleus, the motor nucleus, and the spinal trigeminal tract and nucleus. The spinal trigeminal tract and nucleus extend from the midpons caudally into the upper cervical cord at the C2-C4 levels. The trigeminal nerve is divided into 3 main divisions, known as the ophthalmic (V1), maxillary (V2), and mandibular (V3) branches [3]. Symptoms of trigeminal neuropathy or neuropathic pain syndromes vary with the involved segment and division and may or may not include other sensory deficits (such as facial numbness) or motor deficits (such as weakness with mastication).
Cranial Neuropathy. FDG-PET/CT Efforts using functional MRI, single-photon emission CT, and fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET in studying olfactory dysfunction and the role of olfaction in neurodegenerative disorders remain largely investigative and are not generally used in routine evaluations [42-48]. MRA Head There is no relevant literature to support the use of MRA head in the evaluation of the olfactory nerve. MRI Head MRI is the mainstay for directly imaging the olfactory apparatus and is best assessed with MRI orbits, face, and neck MRI rather than MRI head, allowing for assessment of the sinonasal components of the olfactory apparatus while simultaneously evaluating the relevant brain structures that can affect olfaction. US Neck There is no relevant literature to support the use of ultrasound (US) neck in the evaluation of the olfactory nerve. Variant 2: Unilateral isolated weakness of the mastication muscles, paralysis of the mastication muscles, sensory abnormalities of the face and head, facial numbness, or trigeminal neuralgia (trigeminal nerve, CN V). Initial imaging. The trigeminal nerve (CN V) is the largest CN, providing general sensation to the face, part of the scalp, the nasal cavity, oral cavity, and teeth. It also provides branchial motor innervation to the muscles of mastication. The 4 central trigeminal nerve nuclei are located within the brainstem and include the mesencephalic nucleus, the principal sensory nucleus, the motor nucleus, and the spinal trigeminal tract and nucleus. The spinal trigeminal tract and nucleus extend from the midpons caudally into the upper cervical cord at the C2-C4 levels. The trigeminal nerve is divided into 3 main divisions, known as the ophthalmic (V1), maxillary (V2), and mandibular (V3) branches [3]. Symptoms of trigeminal neuropathy or neuropathic pain syndromes vary with the involved segment and division and may or may not include other sensory deficits (such as facial numbness) or motor deficits (such as weakness with mastication).