srjcmsSRJCMSSRJCMS2788-8851https://doi.org/10.47310/srjcms.2022.v02i01.004CSF Investigations Are Warranted In COVID-19 Patients with Cranial Nerve InvolvementJosefFinstererFulvioAScorzaWith interest we read the article by Correa et al. about cranial nerve imaging findings in six patients infected with SARS-CoV-2 who developed concomitant facial nerve palsy (n=4), optic nerve involvement (n=1), abducens palsy (n=1), and an olfactory nerve lesion (n=1) [1]. It was concluded that the full neurological features of COVID-19 remain to be characterized, that cranial nerve lesions are part of COVID-19, and that MRI can help detecting these abnormalities [1]. We have the following comments and concerns. An infection with SARS-CoV-2 may not only be associated with a lesion of cranial nerves I, II, VI, or VII but has been reported also for cranial nerves III [2], IX and X [3]. In the method section it is stated that all patients presented with pulmonary symptoms [1]. However, patient-4 had only mild fever and a sore throat, patient-5 had only fever and myalgia, and patient-6 had only fever [1]. This discrepancy should be clarified.  Affection of cranial nerves may occur in the context of Guillain-Barre syndrome (GBS) [4]. Thus, it is crucial that GBS is excluded in all patients in whom a clear etiological determination is not possible, such as patient-4, patient-5, and patient-6. Cranial nerve lesions may also occur together with Bickerstaff encephalitis, a subtype of GBS. We should know if Bickerstaff encephalitis was appropriately excluded in each patient.  SARS-CoV-2 as the cause of bilateral, peripheral facial palsy in patient-6 was not substantiated. The patient was only mildly symptomatic (fever) and facial palsy developed two weeks after having been tested positive for SARS-CoV-2. Furthermore, enhancement of the nerve was found in the canalicular and labyrinthine portions, a location which is frequently affected in Bell’s palsy [5]. Thus, it is conceivable that facial palsy was in fact Bell’s palsy and independent of the previous SARS-CoV-2 infection. A further argument for Bell’s palsy is the beneficial effect of steroids. There is also no convincing findings arguing in favour of a causal relation between SARS-CoV-2 and right unilateral, peripheral facial palsy in patient-4 [1]. The patient only presented with mild fever and sore throat. Facial palsy developed 10 days after the initial symptoms. Thus, it is conceivable that also patient-4 had Bell’s palsy without a causal relation to SARS-CoV-2. A further argument against the SARS-CoV-2 etiology is that the frequency of peripheral facial palsies did not increase since the outbreak of the pandemic.  We also should know how a subacute, lacunar ischemic stroke in the pons of patient-3 was excluded. The MRI findings regarding the right facial nerve are not convincing. It is more likely that the right facial nerve was affected by the abducens nucleus lesion since the facial nerve surrounds the abducens nucleus in this location. The authors argue that SARS-CoV-2 does not occur in the CSF but only patient-5 underwent CSF investigations.  In patient-2. optic neuritis was diagnosed. How was acute, ischemic optic neuropathy (AION) or posterior, ischemic optic neuropathy (PION) excluded? Even if aquaporin antibodies are negative, neuromyelitis optica (NMO) can be present. Were MOG-antibodies positive? We should know the results of CSF investigations, if intrathecal   IgG   were  elevated   and if oligoclonal bands(OCB) were positive. It is also conceivable that that patient had a retro-bulbar neuritis (RBN) and has to be diagnosed with cerebral isolated syndrome (CIS). A further shortcoming of the study is that no delineation between central and peripheral facial palsy was carried out. The distinction is crucial for diagnostic and therapeutic purposes.  Overall, the interesting study has several shortcomings, which should be addressed before drawing conclusions as those presented. Particularly, a causal relation between SARS-CoV-2 should be established in patient-4, patient-5, and patient-6, peripheral and central facial nerve lesion should be delineated, nerve conduction studies should be carried out to confirm the peripheral nature of the lesion, and in all patients GBS should be excluded.