Contralateral Nostril Research Articles

Bilateral Alignment of Receptive Fields in the Olfactory Cortex.

Each olfactory cortical hemisphere receives ipsilateral odor information directly from the olfactory bulb and contralateral information indirectly from the other cortical hemisphere. Since neural projections to the olfactory cortex are disordered and non-topographic, spatial information cannot be used to align projections from the two sides like in the visual cortex. Therefore, how bilateral information is integrated in individual cortical neurons is unknown. We have found, in mice, that the odor responses of individual neurons to selective stimulation of each of the two nostrils are significantly correlated, such that odor identity decoding optimized with information arriving from one nostril transfers very well to the other side. Nevertheless, these aligned responses are asymmetric enough to allow decoding of stimulus laterality. Computational analysis shows that such matched odor tuning is incompatible with purely random connections but is explained readily by Hebbian plasticity structuring bilateral connectivity. Our data reveal that despite the distributed and fragmented sensory representation in the olfactory cortex, odor information across the two hemispheres is highly coordinated.Significance statement Like other sense organs, animals typically have two nostrils, but how odor information from the two sides is combined to build bilateral olfactory representations remains largely unknown. Grimaud et al. find that the responses of neurons in the olfactory cortex in awake mice to odors presented separately to the ipsilateral or contralateral nostril are significantly correlated, beyond chance. Such aligned responses could arise from Hebbian plasticity in interhemispheric connections that relies on common odor experiences across the two nostrils. While responses are correlated, the remaining asymmetries in responses to the two nostrils allowed decoding of stimulus laterality. This study points to unexpected order in an olfactory circuit and prompts future work on how olfactory experience can shape interhemispheric information integration.

Impact of local anesthesia on ciliary dyskinesia diagnosis by digital high-speed videomicroscopy.

It was hypothesized that local anesthesia administration would not significantly affect ciliary function in nasal epithelium. A prospective, simple-blind randomized study was conducted between 2020 and 2023. The study employed digital high-speed videomicroscopy to analyze ciliary beat frequency and pattern. A cohort of 38 participants was recruited, consisting of 25 healthy volunteers and 13 referred individuals (including seven diagnosed with PCD). Selection criteria ensured the absence of chronic respiratory diseases, recent respiratory tract infections, or regular use of nasal medications. Participants underwent nasal brushing with administration of lidocaine and naphazoline nasal spray in one nostril and saline in the contralateral nostril. Ciliary beat frequency and pattern were measured using digital high-speed video microscopy. Nasal spray administration did not significantly alter ciliary beat frequency or pattern compared to saline (p = 0.841 and p = 0.125, respectively). Subgroup analysis revealed consistent results across healthy volunteers, referred patients, and PCD patients. Local anesthesia with lidocaine and naphazoline spray did not affect ciliary function outcomes. These findings support the safe use of these agents in clinical practice for PCD diagnostic procedures. Further research with larger cohorts is warranted for validation.

Effect of the extent of posterior septectomy on surgical access during the endoscopic endonasal approach to the sella: A technical note

BackgroundUsing the bi-nostril 4-hand technique during the endoscopic endonasal approach (EEA) facilitates bimanual microsurgical techniques yet requires resection of the posterior nasal septum. The surgical exposure and degree of maneuverability gained proportionate to the extent of posterior septectomy in the sagittal plane was previously quantified. Research questionWe aim to describe our technique of posterior septectomy, and the effect of its extent in the axial plane on surgical access, and instrument maneuverability. Material and methodsAfter fracturing the posterosuperior nasal septum, we disarticulate the vomer from the sphenoid rostrum and remove its upper part. The sphenoid rostrum is excised next exposing the clival recess where a suction tip without a side channel is anchored, allowing the assisting surgeon to use an additional instrument in their dominant hand. The vomer is removed down to the level of the floor of the sphenoid sinus. ResultsA wide exposure is achieved in the coronal plane bilaterally at the level of the sphenoid rostrum allowing unobstructed instrument manipulation in the craniocaudal and cross-court trajectories. Furthermore, the floor of the sella is reached through a straight rather than angled trajectory facilitating surgical access, manipulation, and instrument maneuverability. For lateral lesions requiring contralateral access, the assisting surgeon can assist in dissection from the contralateral nostril without changing the position of the endoscope. Discussion and conclusionRemoving the upper vomer improves surgical access, and instrument maneuverability. Simultaneous dissection from both nostrils might be attempted. Caudally extending the posterior septectomy during the EEA allows better exposure and improves surgical access in all planes.

Odor representations from the two nostrils are temporally segregated in human piriform cortex

The human olfactory system has two discrete channels of sensory input, arising from olfactory epithelia housed in the left and right nostrils. Here, we asked whether the primary olfactory cortex (piriform cortex [PC]) encodes odor information arising from the two nostrils as integrated or distinct stimuli. We recorded intracranial electroencephalogram (iEEG) signals directly from PC while human subjects participated in an odor identification task where odors were delivered to the left, right, or both nostrils. We analyzed the time course of odor identity coding using machine-learning approaches and found that uni-nostril odor inputs to the ipsilateral nostril are encoded ∼480-ms faster than odor inputs to the contralateral nostril on average. During naturalistic bi-nostril odor sampling, odor information emerged in two temporally segregated epochs, with the first epoch corresponding to the ipsilateral and the second epoch corresponding to the contralateral odor representations. These findings reveal that PC maintains distinct representations of odor input from each nostril through temporal segregation, highlighting an olfactory coding scheme at the cortical level that can parse odor information across nostrils within the course of a single inhalation.

Effective Correction of Columellar Base Deviation in Primary Unilateral Cleft Lip Repair: A Muscle-Driven Method.

Columellar base deviation is a common and challenging deformity in patients with unilateral cleft lip. Debate continues on its surgical correction without sufficient studies to establish effective management. This article presents the authors' experience in correcting the columellar base deviation with the muscle-driven method in primary lip repair. The key is to perform extensive muscle dissection and reconstruction. In the medial lip segment, muscle dissection is performed subcutaneously up to the contralateral nostril floor for effective lengthening and rotation. In the lateral lip segment, muscle dissection is executed in both submucosal and subcutaneous planes, and muscle component is extensively separated from the lip skin and buccal mucosa. The lateral muscle flap is advanced and reattached to the contralateral nostril floor and columellar base using a subcutaneous sustaining suture. Cinching suture between columellar base and alar base is performed. These 2 sutures help centralize and overcorrect the columellar base. Bilateral muscle components are reoriented and approximated in a Z-plasty format for lengthening of the lip. The patients were followed up for at least 3 years. Quantitative measurements of deviation in columellar base angulation were taken and revealed 55.8 ± 2.6 degrees (before nasoalveolar molding), 29.6 ± 1.7 degrees (after nasoalveolar molding), and 2.8 ± 0.4 degrees (postoperative follow-up), respectively. The muscle-driven method represents a safe and effective technique to correct columellar base deviation in patients with unilateral cleft lip.

Rigid normograde rhinoscopy-assisted traction-avulsion removal of small middle ear polyps from the auditory tube in five cats.

This study aims to describe a novel minimally invasive technique for the removal of small middle ear polyps from the auditory tube openings in cats. Five cats with clinical signs of otitis externa and/or otitis media, and/or upper respiratory tract inflammation were included. All cats underwent pharyngolaryngoscopy under anaesthesia, CT scan of the head, neck and thoracic cavity, video-otoscopic examination, retrograde nasopharyngoscopy and normograde rhinoscopy. The five cats described in this study were all found to have significant respiratory tract inflammation (rhinitis, sinusitis, nasopharyngitis, otitis media) with small polypous protrusions from the auditory tube openings. A normograde rhinoscopy-assisted traction-avulsion (RATA) removal of these small polyps was performed in all cases without complications. The rostral nasopharynx was visualised by a unilaterally normograde advanced rigid endoscope passing the choana, and polyps were removed using a grasping forceps introduced in the contralateral nostril. Telephone follow-up revealed clear improvement in all cases. One of the cases was re-evaluated with a CT scan and endoscopy 4 weeks after treatment. The CT scan showed a significant improvement with no abnormalities in both external ear canals and air opacity in both tympanic bullae. Video-endoscopic examination revealed intact tympanic membranes with mild chronic abnormalities and patent auditory tube openings upon normograde rhinoscopy. Rigid normograde RATA is a novel, minimally invasive and effective technique for the removal of small middle ear polyps from auditory tube openings in cats with otitis media.

Optimization of sniff nasal inspiratory pressure (SNIP) measurement methodology in healthy subjects

BackgroundMaximal inspiratory pressure (MIP) is currently the most commonly used measure for respiratory muscle strength (RMS) estimation, however, requires significant effort. Falsely low values are therefore common, especially in fatigue-prone subjects, such as neuromuscular disorder patients. In contrast, sniff nasal inspiratory pressure (SNIP) requires a short, sharp sniff; this is a natural manoeuvre, decreasing required effort. Consequently, it has been suggested that use of SNIP could confirm the accuracy of MIP measurements. However, no recent guidelines regarding the optimal method of SNIP measurement exist, and varied approaches have been described.ObjectivesWe compared SNIP values from three conditions, namely with 30, 60 or 90 s time intervals between repeats, the right (SNIPR) and left (SNIPL) nostril, and the contralateral nostril occluded (SNIPO) or non-occluded (SNIPNO). Additionally, we determined the optimal number of repeats for accurate SNIP measurement.Method52 healthy subjects (23 males) were recruited for this study, of which a subset of 10 subjects (5 males) completed tests comparing the time interval between repeats. SNIP was measured from functional residual capacity via a probe in one nostril, while MIP was measured from residual volume.ResultsThere was no significant difference in SNIP depending on the interval between repeats (P = 0.98); subjects preferred the 30 s. SNIPO was significantly higher than SNIPNO (P < 0.00001) but SNIPL and SNIPR did not significantly differ (P = 0.60). There was an initial learning effect for the first SNIP test; SNIP did not decline during 80 repeats (P = 0.64).ConclusionsWe conclude that SNIPO is a more reliable RMS indicator than SNIPNO, as there is reduced risk of RMS underestimation. Allowing subjects to choose which nostril to use is appropriate, as this did not significantly affect SNIP, but may increase ease of performance. We suggest that twenty repeats is sufficient to overcome any learning effect and that fatigue is unlikely after this number of repeats. We believe these results are important in aiding the accurate collection of SNIP reference value data in the healthy population.

A randomized control trial employing infraorbital nerve stimulation as a neural distractor during nasopharyngeal swab.

With the global COVID-19 pandemic, nasopharyngeal swabbing has become commonplace and can occasionally cause discomfort, tearing, and anxiety. To evaluate whether using a neural distraction device during nasopharyngeal swabbing can mitigate patient discomfort. Participants were randomized into nasal swab with vibration first (treatment-control or Tc) or nasal swab without vibration first (control-treatment or Ct). Then the swab was repeated with the opposite technique. The vibration device was used to stimulate the infraorbital nerve at the midpupillary line, while a nasopharyngeal swab was performed according to CDC protocol. After each swab, participants filled out a survey to assess pain, discomfort, and tearing. This procedure was replicated on the contralateral nostril for a total of 4 swabs and 4 surveys. Thirty-four subjects were included in the analysis. In the Ct group, there was a median 1.0-point decrease in pain with the use of vibration (95% CI [-1.8, -0.3], P = 0.0117), 2.5-point decrease (95% CI [-3.0, -0.8], P = 00039) in discomfort, and a 1.0-point decrease (95% CI [-2.6, -0.2] P = 0.0303) in tearing when the vibratory device was used. In the Tc group, there was a median 2.0-point decrease in pain with vibration (95% CI [ -2.7, -1.1], P < 0.0001), 2.3-point decrease in discomfort (95% CI [-3.1, -1.5], P < 0.0001), and a 1.5-point decrease in tearing (95% CI [-2.5, -0.5], P = 0.0037) when vibration was used. Vibratory stimulation of the infraorbital nerve is safe and effectively reduced pain, discomfort, and tearing during nasopharyngeal swab. Vibration is a reasonable option to minimize patient discomfort during COVID-19 or other microbiological testing.

Sinonasal undifferentiated carcinoma: Case report and short literature review

Abstract We present a case of a 48-year-old male patient who was admitted in our clinic for right nasal obstruction, antero-posterior mucopurulent rhinorrhea, recurrent right micro-epistaxis, hyposmia, cacosmia and right hemicrania. ENT findings and CT scan detects proliferative, polylobate, vascularized tumor formation occupying the right nasal nostril, with muco-purulent secretions lining the tumor formation. The tumor pushes the intersinusal wall to the side and the nasal septum to the contralateral nostril. The apparent origin is at the level of the right middle nasal meatus, but we could not identify a clear limit from the nasopharynx lateral and posterior wall. Resection of the entire tumor formation was performed under endoscopic control. The histopathological outcome revealed undifferentiated carcinoma; immunohistochemical tests were performed and support the myoepithelial origins.

Endoscopic Endonasal Approach to the Ventral-Medial Portion of Posterior Paramedian Skull Base: A Morphometric Perspective of Surgical and Radiologic Anatomy

This study aims to provide morphometric analysis of endoscopic endonasal approach (EEA) to the ventral-medial portion of posterior paramedian skull base. Furthermore, it aims to investigate the surgical exposure obtained through EEA with and without eustachian tube (ET) removal, emphasizing the role of contralateral nostril (CN) access. Five fresh adult head specimens were prepared for dissection. A predissection and a postdissection computed tomography study was performed. A surgically oriented classification into 4 regions was used: 1) tubercular region; 2) occipital condyle region; 3) parapharyngeal space (PPhS) region; and 4) jugular foramen (JF) region. The Student t-test was used to compare angulations and measures of EEA with access from the ipsilateral and CN, respectively, with and without ET removal. EEA to the ventral-medial portion of posterior paramedian skull base encompasses 2 medial trajectories (transtubercular and transcondylar) and 2 lateral pathways to the PPhS and JF. The CN access, without removal of the ET, allows a complete exposure of the petrous and intrajugular portion of the JF and superior PPhS without exposition of the parapharyngeal segment of internal carotid artery. The ipsilateral nostril approach with ET removal allows to obtain a wider exposure, reaching the medial sigmoid part of the JF. No significant differences exist in regard to transtubercular and transcondylar approaches. This study suggests that EEA to posterior paramedian skull base allows the realization of a corridor directed to the jugular tubercle, occipital condyle, medial PPhS, and ventral-medial JF. The CN approach with ET preservation can expose the petrous and intrajugular parts of the JF and PPhS. Case series are needed to demonstrate benefits and drawbacks of these approaches.

Nasal airflow engages central olfactory processing and shapes olfactory percepts.

Binding of airborne odour molecules to olfactory receptors at the top of the nasal cavity gives rise to our rich olfactory experience. Whether airflow plays a role in human olfactory perception beyond the transportation of odorants is scantly known. Combining psychophysical measures with strict controls of nasal flow parameters, we demonstrate in four experiments that the perceived intensity of a unilaterally presented odour decreases systematically with the amount of contralateral nasal airflow, in manners that are independent of odour flow rate, nasal pressure, perceived sniff vigour or attentional allocation. Moreover, the effect is due to the sensed rather than the factual amount of nasal flow, as applying a local anaesthetic to the contralateral nostril produces the same effect as physically blocking it. Our findings indicate that nasal flow spontaneously engages central olfactory processing and serves as an integral part of the olfactory percept in humans.

Endoscopic endonasal intracanalicular optic nerve decompression: how I do it.

The endoscopic endonasal approach for optic nerve decompression is suited for the management of non-traumatic optic neuropathy but remains underreported, presumably due to transcranial approaches still being favoured at individual centres. The optic canal is approached endoscopically and transsphenoidally through the contralateral nostril. Its inferomedial wall is opened using an irrigated diamond drill, and neuronavigation is used to confirm anatomical bearings. This technique provides rapid and easy access to the inferomedial aspect of the optic canal and nerve. Optic nerve decompression through this approach is associated with low morbidity and should be considered as an alternative to transcranial approaches.

Suction mitigation of airborne particulate generated during sinonasal drilling and cautery.

BackgroundCoronavirus disease 2019 (COVID‐19) has significantly impacted endonasal surgery, and recent experimentation has demonstrated that sinonasal drilling and cautery have significant propensity for airborne particulate generation immediately adjacent to the surgical field. In the present investigation, we assessed nasopharyngeal suctioning as a mitigation strategy to decrease particulate spread during simulated endonasal surgical activity.MethodsAirborne particulate generation in the 1‐µm to 10‐µm range was quantified with an optical particle sizer in real‐time during cadaveric‐simulated anterior and posterior endonasal drilling and cautery conditions. To test suction mitigation, experiments were performed both with and without a rigid suction placed in the contralateral nostril, terminating in the nasopharynx.ResultsBoth anterior (medial maxillary wall and nasal septum) and posterior (sphenoid rostrum) drilling produced significant particulate generation in the 1‐µm to 10‐µm range throughout the duration of drilling (p < 0.001) without the use of suction, whereas nasopharyngeal suction use eliminated the detection of generated airborne particulate. A similar effect was seen with nasal cautery, with significant particle generation (p < 0.001) that was reduced to undetectable levels with the use of nasopharyngeal suction.ConclusionThe use of nasopharyngeal suctioning via the contralateral nostril minimizes airborne particulate spread during simulated sinonasal drilling and cautery. In the era of COVID‐19, this technique offers an immediately available measure that may increase surgical safety.

Evaluation of Validity and Specificity of the Cottle Maneuver in Diagnosis of Nasal Valve Collapse.

Despite the widespread use of the Cottle maneuver as a finding to define nasal valve collapse, no studies have confirmed the association between a positive Cottle maneuver and need for nasal valve repair. This study demonstrates the low construct validity of the Cottle maneuver. One hundred healthy volunteer students and employees at Boston Medical Center were recruited for this study. Participants were asked to evaluate their breathing on a 10-point scale, rating their subjective airflow in each nostril while occluding the contralateral nostril, where 0 indicated complete obstruction and 10 indicated complete patency. Following the baseline ratings, participants were asked to rate their breathing once again while examiners preformed the Cottle and modified Cottle maneuvers. Overall, 97 percent of participants reported improved airflow in each nostril following the Cottle maneuver (p < 0.00001); 98 percent reported improved airflow in each nostril following the modified Cottle maneuver (p < 0.00001). If the clinical consensus regarding the observed improvement in nasal airflow is to be followed, nearly all the participants recruited are experiencing some surgically correctable nasal obstruction. Given the population from which our cohort was collected-students and residents from a medical campus-such a conclusion seems extremely unlikely. We believe the more likely explanation for the high positive test rate is flawed assumptions of the Cottle and modified Cottle maneuvers. Therapeutic, V.

A new technique for perioral muscle reconstruction and lip lengthening in complete unilateral cleft lip

BackgroundAdequate skin lengthening and symmetry may not be consistently obtained in unilateral cleft lip repair, especially in patients with complete cleft. The purpose of this study was to present the model of muscle dissection and approximation to facilitate lip lengthening and symmetry. MethodsThe design followed the rotation-advancement (RA) method without skin measurement. A curvilinear skin incision was made from subnasale to the Cupid's bow peak (CBP). Muscle dissection was continued to the contralateral nostril floor beneath the columellar base to facilitate downward rotation in the medial lip. Wide muscle dissection was performed in the lateral lip segment from the nasal mucosa passing the alar base. The lateral lip muscle was advanced and sutured to the medial lip muscle in a Z-plasty fashion. A small skin backcut was made above the CBP. Primary nasal correction was performed. A series of 138 patients with complete unilateral cleft lip and palate were included in this study. Standard photographs were collected for measurement in the nasolabial region. ResultsAdequate lengthening and symmetry of the lip was obtained. The ratio of vertical philtral height was 0.99±0.05 between the cleft and noncleft sides. The C flap was used for supplementary skin lengthening in 58% of cases. Postoperative lip retraction requiring massage occurred in 13%. Overall nasolabial appearance was satisfactory. ConclusionThe new technique of perioral muscle reconstruction facilitated to obtain lip lengthening and symmetry in the repair of complete unilateral cleft lip.

Longitudinal analysis of sniff nasal inspiratory pressure assessed using occluded and un-occluded measurement techniques in amyotrophic lateral sclerosis and primary lateral sclerosis

Objective: Sniff nasal inspiratory pressure (SNIP) is a commonly used clinical measure of respiratory impairment in amyotrophic lateral sclerosis (ALS), which is used to guide the initiation of noninvasive ventilation (NIV). SNIP can be completed with either an occluded or an un-occluded contralateral nostril. The aim of this study was to compare occluded and un-occluded SNIP measurements and to examine the decline in occluded SNIP over time compared to the ALSFRS-R respiratory subscore. Methods: This was a prospective longitudinal study examining occluded and un-occluded SNIP scores in ALS and PLS patients recorded between 2001 and 2018. Bland and Altman graphs were plotted for occluded vs. un-occluded SNIP measurements taking account of the repeated measures nature of the data. Longitudinal models were constructed as linear mixed effects multi-level models with follow-up in ALS limited to 6 years. Results: SNIP measured with an occluded contralateral nostril was systematically higher than with an un-occluded nostril. SNIP measured using both methods declined non-linearly, particularly after 2–3 years. The best fit model for decline in occluded SNIP included a main effect and interaction between site of onset and time, with age and diagnostic delay as independent variables. This showed a linear decline in spinal onset with a floor effect in bulbar-onset ALS. Conclusion: SNIP measured with an occluded and un-occluded contralateral nostril is not interchangeable, which is relevant in interpreting thresholds for initiation of NIV. SNIP declines non-linearly, which is explained in spinal onset ALS by age and diagnostic delay, but an apparent floor effect remains in bulbar onset.

Genioglossus activation during maximal sniff manoeuvres: Is upper airway function relevant in the clinical assessment of inspiratory and expiratory muscle strength?

Genioglossus activation during maximal sniff manoeuvres: Is upper airway function relevant in the clinical assessment of inspiratory and expiratory muscle strength?

A Mirror-Symmetric Excitatory Link Coordinates Odor Maps across Olfactory Bulbs and Enables Odor Perceptual Unity

Sensory input reaching the brain from bilateral and offset channels is nonetheless perceived as unified. This unity could be explained by simultaneous projections to both hemispheres, or inter-hemispheric information transfer between sensory cortical maps. Odor input, however, is not topographically organized, nor does it project bilaterally, making olfactory perceptual unity enigmatic. Here we report a circuit that interconnects mirror-symmetric isofunctional mitral/tufted cells between the mouse olfactory bulbs. Connected neurons respond to similar odors from ipsi- and contra-nostrils, whereas unconnected neurons do not respond to odors from the contralateral nostril. This connectivity is likely mediated through a one-to-one mapping from mitral/tufted neurons to the ipsilateral anterior olfactory nucleus pars externa, which activates the mirror-symmetric isofunctional mitral/tufted neurons glutamatergically. This circuit enables sharing of odor information across hemispheres in the absence of a cortical topographical organization, suggesting that olfactory glomerular maps are the equivalent of cortical sensory maps found in other senses.

Validation of Simple Methods to Select a Suitable Nostril for Nasotracheal Intubation.

Background Nasotracheal intubation is a blind procedure that may lead to complications; therefore, several tests were introduced to assess a suitable nostril for nasotracheal intubation. However, the value of simple tests in clinical practice was insufficient to evaluate. Method A diagnostic prospective study was conducted in 42 patients, ASA classes I–III, undergoing surgery requiring nasotracheal intubation for general anesthesia. Two simple methods for assessing the patency of nostrils were investigated. Firstly, the occlusion test was evaluated by asking for the patient's own assessment of nasal airflow during occlusion of each contralateral nostril while in a sitting posture. Secondly, patients breathed onto a spatula held 1 cm below the nostrils while in a sitting posture. All patients were assessed using these two simple tests. Nasal endoscopic examination of each patient was used as a gold standard. Results The diagnostic value of the occlusion test (sensitivity of 91.7%, specificity of 61.1%, PPV of 75.9%, NPV of 84.6%, LR+ of 2.36, and LR− of 0.14) seemed better than that of the spatula test (sensitivity of 95.8%, specificity of 25.0%, PPV of 63.0%, NPV of 81.8%, LR+ of 1.28, and LR− of 0.17). When both tests were combined in series, the diagnostic value increased (sensitivity of 87.9%, specificity of 70.8%, PPV of 80.1%, NPV of 81.4%, LR+ of 3.01, and LR− of 0.17). Conclusion and Recommendations The simple occlusion test is more useful than the spatula test. However, combining the results from both tests in series helped to improve the diagnostic value for selecting a suitable nostril for nasotracheal intubation.

Sniff nasal inspiratory pressure (SNIP) in amyotrophic lateral sclerosis: Relevance of the methodology for respiratory function evaluation

ObjectivesWe investigated two different methodological approaches for determining nasal inspiratory pressure during a sniff (SNIP) in patients with Amyotrophic Lateral Sclerosis (ALS). Patients and MethodsWe included 37 ALS patients and 11 controls. SNIP was measured in the sitting position, performed in each nostril with (SNIPocclud) and without (SNIPopen) closing the contralateral nostril. The best of 3 consistent results was considered for analyses. Patients were also assessed with MIP and the revised functional ALS rating scale (ALSFRS-R). Mann-Whitney U test, Wilcoxon test and Spearman's rank correlation coefficient with Bonferroni correction were applied. Coefficient of variation (CV) was calculated. ResultsSNIP was significantly lower in patients than controls, either for SNIPopen (p = 0.011) or SNIPocclud (p = 0.002). SNIPopen values were significantly lower both in ALS patients and controls than SNIPocclud (p < 0.001 and p = 0.007, respectively). SNIPopen CV was 8.14% and 8.51%, while SNIPocclud CV was 4.98% and 6.37%, respectively for controls and patients. SNIPopen and SNIPocclud were strongly correlated in both groups (r = 0.761 for controls; r = 0.768 for patients). In ALS, both methods were moderately correlated with MIP (respectively r = 0.525, p = 0.006 and r = 0.685, p < 0.001) and the respiratory subscore of ALSFRS-R (respectively r = 0.525, p = 0.001 and r = 0.64, p < 0.001). Although bulbar and spinal onset patients presented no differences for SNIPopen (p = 0.157), significant differences were found for SNIPocclud (p = 0.018). ConclusionSNIPocclud should be considered when evaluating ALS patients as its values present lower variability and favor longer follow-up.