Lower Four Cranial Nerves in the Management of Glomus Jugulare: Anatomical Study

Abstract Introduction The surgical management that achieves minimal morbidity and mortality for patients with glomus and non-glomus tumors involving the jugular foramen (JF) region requires a comprehensive understanding of the complex anatomy, anatomic variability, and pathological anatomy of this region. Objective The aim of this study is to propose a rational guideline to expose and preserve the lower cranial nerves (CNs) in the lateral approach of the JF. Methods The technique utilized is the gross and microdissection of 4 fixed cadaveric heads to revise the JF's surgical anatomy and high part of the carotid sheath compared with surgical cases to understand and preserve the integrity of lower CNs. The method involves radical mastoidectomy, microdissection of the JF, facial nerve, and high neck just below the carotid canal and the JF. The CNs IX, X, XI, and XII are microscopically dissected and kept in sight up to the JF. Results This study realized well the surgical and applied anatomy of the lower CNs with relation to the facial nerve and JF. Conclusions The JF anatomy is complicated, and the key to safely operate on it and preserving the lower CNs is to find the posterior belly of the digastric muscle, to skeletonize the facial nerve, to remove the mastoid tip preserving the stylomastoid foramen, to skeletonize the sigmoid sinus and posterior fossa dura not only anterior but also posteroinferior to reach and drill the jugular tubercle.

Lower Four Cranial Nerves in the Management of Glomus Jugulare: Anatomical Study.

Introduction The surgical management that achieves minimal morbidity and mortality for patients with glomus and non-glomus tumors involving the jugular foramen (JF) region requires a comprehensive understanding of the complex anatomy, anatomic variability, and pathological anatomy of this region. Objective The aim of this study is to propose a rational guideline to expose and preserve the lower cranial nerves (CNs) in the lateral approach of the JF. Methods The technique utilized is the gross and microdissection of 4 fixed cadaveric heads to revise the JF's surgical anatomy and high part of the carotid sheath compared with surgical cases to understand and preserve the integrity of lower CNs. The method involves radical mastoidectomy, microdissection of the JF, facial nerve, and high neck just below the carotid canal and the JF. The CNs IX, X, XI, and XII are microscopically dissected and kept in sight up to the JF. Results This study realized well the surgical and applied anatomy of the lower CNs with relation to the facial nerve and JF. Conclusions The JF anatomy is complicated, and the key to safely operate on it and preserving the lower CNs is to find the posterior belly of the digastric muscle, to skeletonize the facial nerve, to remove the mastoid tip preserving the stylomastoid foramen, to skeletonize the sigmoid sinus and posterior fossa dura not only anterior but also posteroinferior to reach and drill the jugular tubercle.

An atypical stapedial artery.

The persistence of the stapedial artery is a rare vascular anomaly. It is mostly asymptomatic but sometimes cause conductive hearing loss, pulsatile tinnitus, or vertigo. The estimated prevalence of this rare postembryonic persistence ranged from 0.02% to 0.48%. Four different anatomical forms have been identified, and their preoperative diagnostic is essential. We report the case of an incidental discovery of pharyngo-hyo-stapedial artery, the most uncommon form of persistent stapedial artery. Its per-operative finding has become rare because tomodensitometry is performed in case of conductive hearing loss. The continuous improvement of imagery resolution will probably help to revise the incidence of this malformation.

Endoscope-assisted retrosigmoid approach in hemifacial spasm: our experience / Abordagem retrosigmóidea assistida por endoscopia em espasmo hemifacial: nossa experiência

Abstract Introduction: The use of surgical decompression of facial hemispasm due to the loop in the internal auditory canal is not always accepted due to the risk related to the surgical procedure. Currently a new surgical technique allows surgeons to work in safer conditions. Objective: To report the results with endoscope-assisted retrosigmoid approach for facial nerve microvascular decompression in hemifacial spasm due to neurovascular conflict. The surgical technique is described. Methods: We carried out a prospective study in a tertiary referral center observing 12 (5 male, 7 female) patients, mean age 57.5 years (range 49-71) affected by hemifacial spasm, that underwent to an endoscope assisted retrosigmoid approach for microvascular decompression. We evaluated intra-operative findings, postoperative HFS resolution and complication rates. Results: Hemifacial spasm resolution was noticed in 9/12 (75%) cases within 24 h after surgery and in 12/12 (100%) subjects within 45 days. A significant (p < 0.001) correlation between preoperative historical duration of hemifacial spasm and postoperative recovery timing was recorded. Only 1 patient had a complication (meningitis), which resolved after intravenous antibiotics with no sequelae. No cases of cerebrospinal fluid leak, facial palsy or hearing impairment were recorded. Hemifacial spasm recurrence was noticed in the only subject where the neurovascular conflict was due to a vein within the internal auditory canal. Conclusions: The endoscope assisted retrosigmoid approach technique offers an optimal visualization of the neurovascular conflict thorough a minimally invasive approach, thus allowing an accurate decompression of the facial nerve with low complication rates. Due to the less invasive nature, the procedure should be considered in functional surgery of the cerebellar pontine angle as hemifacial spasm treatment, specially when the procedure is performed by an otolaryngologist.

Resumo Introdução: O uso de descompressão cirúrgica do espasmo hemifacial devido ao loop no canal auditivo interno nem sempre é aceito devido ao risco relacionado ao procedimento cirúrgico. Atualmente, uma nova técnica cirúrgica permite trabalhar em condições seguras. Objetivo: Relatar os resultados que obtivemos com a abordagem retrosigmóidea assistida por endoscopia para a descompressão microvascular do nervo facial em casos de espasmo hemifacial devido a conflito neurovascular. A técnica cirúrgica é descrita. Método: Realizamos um estudo prospectivo em um centro de referência terciária observando 12 pacientes (5M, 7F), com média de idade de 57,5 (intervalo 49-71) anos com espasmo hemifacial submetidos a uma abordagem retrosigmóide assistida por endoscopia para descompressão microvascular. Foram avaliados os achados intraoperatórios, a resolução pós-operatória do espasmo hemifacial e as taxas de complicações. Resultados: A resolução do espasmo hemifacial foi observada em 9/12 (75%) dos casos nas 24 horas após a cirurgia e em 12/12 (100%) dos indivíduos até 45 dias. Uma correlação significativa (p < 0,001) entre a duração do histórico pré-operatório de espasmo hemifacial e o tempo de recuperação pós-operatório foi registrado. Apenas um paciente apresentou uma complicação (meningite), que foi resolvida após administração de antibióticos por via intravenosa sem sequelas. Nenhum caso fístula liquórica, paralisia facial ou deficiência auditiva foi registrado. A recorrência do espasmo hemifacial foi observada em único indivíduo em quem o conflito neurovascular foi causado por um vaso no interior do canal auditivo interno. Conclusões: A técnica da abordagem retrosigmóidea assistida por endoscopia oferece uma ótima visualização do conflito neurovascular através de uma abordagem minimamente invasiva, permite assim uma descompressão precisa do nervo facial com baixas taxas de complicações. Por ser menos invasivo, o procedimento deve ser considerado na cirurgia funcional do ângulo pontocerebelar como tratamento de espasmo hemifacial, especialmente quando o procedimento é feito por um otorrinolaringologista.

Endoscope-assisted retrosigmoid approach in hemifacial spasm: our experience.

INTRODUCTION: The use of surgical decompression of facial hemispasm due to the loop in the internal auditory canal is not always accepted due to the risk related to the surgical procedure. Currently a new surgical technique allows surgeons to work in safer conditions. OBJECTIVE: To report the results with endoscope-assisted retrosigmoid approach for facial nerve microvascular decompression in hemifacial spasm due to neurovascular conflict. The surgical technique is described. METHODS: We carried out a prospective study in a tertiary referral center observing 12 (5 male, 7 female) patients, mean age 57.5 years (range 49-71) affected by hemifacial spasm, that underwent to an endoscope assisted retrosigmoid approach for microvascular decompression. We evaluated intra-operative findings, postoperative HFS resolution and complication rates. RESULTS: Hemifacial spasm resolution was noticed in 9/12 (75%) cases within 24h after surgery and in 12/12 (100%) subjects within 45 days. A significant (p<0.001) correlation between preoperative historical duration of hemifacial spasm and postoperative recovery timing was recorded. Only 1 patient had a complication (meningitis), which resolved after intravenous antibiotics with no sequelae. No cases of cerebrospinal fluid leak, facial palsy or hearing impairment were recorded. Hemifacial spasm recurrence was noticed in the only subject where the neurovascular conflict was due to a vein within the internal auditory canal. CONCLUSIONS: The endoscope assisted retrosigmoid approach technique offers an optimal visualization of the neurovascular conflict thorough a minimally invasive approach, thus allowing an accurate decompression of the facial nerve with low complication rates. Due to the less invasive nature, the procedure should be considered in functional surgery of the cerebellar pontine angle as hemifacial spasm treatment, specially when the procedure is performed by an otolaryngologist.

European Position Statement on Diagnosis, and Treatment of Meniere's Disease.

Meniere Disease keeps challenges in its diagnosis and treatment since was defined by Prosper Meniere at the beginning of 19th Century. Several classifications and definition were made until now and speculations still exist on its etiology. As the etiology remains speculative the treatment models remain in discussion also. The European Academy of Otology and Neurotology Vertigo Guidelines Study Group intended to work on the diagnosis and treatment of Meniere's disease and created the European Positional Statement Document also by resuming the consensus studies on it. The new techniques on diagnosis are emphasized as well as the treatment models for each stage of the disease are clarified by disregarding the dilemmas on its treatment. The conservative, noninvasive and invasive therapeutic models are highlighted.

How minimally invasive vestibular neurotomy for incapacitating Meniere's disease improves dizziness and anxiety.

CONCLUSION: Patients with incapacitating Meniere Disease (MD) suffer in their daily lives and activities because of the dizziness and anxiety induced by MD. Minimally Invasive Vestibular Neurotomy (MIVN) is a safe and effective surgical treatment for these individuals, and improved their dizziness and anxiety. OBJECTIVES: This study aimed to assess the state of dizziness and anxiety of patients with incapacitating MD and its improvement through MIVN. METHOD: A total of 118 patients with incapacitating MD who underwent MIVN in France and Japan were evaluated. The DHI (Dizziness Handicap Inventory), SAST (Short Anxiety Screening Test), and STAI (State Trait Anxiety Index) questionnaires were used to evaluate disequilibrium and anxiety. RESULTS: The MIVN method appears safe and effective for patients with incapacitating MD. Pre-operative assessment results by DHI and SAST were significantly related to each other, and were influenced by lifestyle and profession. This prospective study showed that MIVN improved dizziness and anxiety in these patients.

Chemically assisted dissection by means of mesna in cholesteatoma surgery.

OBJECTIVE: To investigate whether the use of mesna (sodium 2-mercaptoethanesulfonate), a mucolytic agent capable of breaking disulfur bonds, reduces the frequency of residual cholesteatoma in canal wall up tympanomastoidectomy. STUDY DESIGN: Retrospective study. SETTING: Tertiary care otology and skull base centers. PATIENTS: Two hundred fourteen patients operated on by means of canal wall up tympanomastoidectomy for a middle ear cholesteatoma. INTERVENTIONS: Planned staged canal wall up tympanomastoidectomy. In the study group, the cholesteatoma removal was performed with the support of chemically assisted dissection by using mesna. In the control group, the dissection of the disease was performed by means of a traditional mechanical technique alone. MAIN OUTCOME MEASURES: Prevalence of residual cholesteatoma at the second-stage operation in the 2 groups of study. RESULTS: One hundred eight patients were treated with the ancillary use of mesna and one hundred six without chemically assisted dissection. A residual cholesteatoma was found in 12 (11.1%) of the 108 patients treated with chemically assisted dissection and in 26 (24.5%) of the 106 patients treated with mechanical dissection. After adjusting for potential confounders, CADISS procedure was associated with a significantly lower risk of having residual cholesteatoma (OR, 0.39; 95% CI, 0.18-0.84, p = 0.02). CONCLUSION: This study showed that chemically assisted dissection by using mesna represents a valid support in reducing the frequency of residual disease in cholesteatoma surgery.

Cochlear effects of intraoperative use of Mesna in cholesteatoma surgery.

BACKGROUND AND AIM OF THE WORK: Mesna is thiol compound proposed as chemical dissector in otolaryngologic surgery. The aim of this study was to address the issue of possible ototoxicity from topical administration of MESNA into the middle ear during otologic surgery. METHODS: Audiological findings of patients (n=55) who underwent canal wall up tympanomastoidectomy with the ancillary use of Mesna in 1-year period were retrospectively reviewed. We identified another set of 51 patients who had undergone otologic surgery without the use of Mesna to serve as a control group. Preoperative and postoperative mean bone conduction thresholds were calculated and compared between the two groups for the frequencies of 500,1000,2000, and 3000; 4000 and 8000 Hz were further analyzed to search for high-frequency sensorineural hearing loss. RESULTS: Fifty-five patients were operated on with the ancillary use of Mesna and 51 underwent surgery with traditional mechanical dissection alone. When mean preoperative bone conduction values were compared with postoperative values, no significant differences were found for any of the frequencies tested in both groups. Analyzing changes in bone conduction at 4000 and 8000 Hz a slight worsening was observed in both groups. CONCLUSIONS: We found no difference in hearing thresholds between the treatment and control groups. Thus, the results of this study confirmed data obtained in laboratory animal models demonstrating that intraoperative use of Mesna in middle ear surgery is safe and does not lead to ototoxic effects.

Intraoperatively diagnosed cerebellopontine angle facial nerve schwannoma: how to deal with it.

OBJECTIVE: This study aimed to report our experience in the management of patients with intraoperatively diagnosed intracranial facial nerve schwannomas (FNSs) and propose a decision-making strategy. METHODS: Twenty-three patients with FNS of the internal auditory canal and/or cerebellopontine angle operated on between 1992 and 2012 were identified. RESULTS: Preoperatively, all cases have been radiographically diagnosed as vestibular schwannomas. Operative procedures consisted of total tumor resection with grafting in 43.4% of patients, near-total resection leaving behind the tumor capsule overlying the facial nerve in 21.7%, total tumor resection with preservation of anatomic continuity of the facial nerve in 13%, and subtotal resection in 4.3%. Four patients (17.4%) underwent bony decompression with no tumor removal. CONCLUSION: Management of FNS diagnosed at surgery represents a significant clinical challenge. We considered total tumor resection with grafting when patients presented with preoperative facial nerve palsy (≥ grade III). Both subtotal and near-total tumor removal can be performed in patients with preoperative good facial function and/or large tumors with brainstem compression. Patients with small tumors who were selected for hearing preservation surgery can be considered for bony decompression. Fascicle preservation surgery may be an option when a clear cleavage plane between the tumor and the facial nerve is found.

Unilateral vestibular loss impairs external space representation.

The vestibular system is responsible for a wide range of postural and oculomotor functions and maintains an internal, updated representation of the position and movement of the head in space. In this study, we assessed whether unilateral vestibular loss affects external space representation. Patients with Menière's disease and healthy participants were instructed to point to memorized targets in near (peripersonal) and far (extrapersonal) spaces in the absence or presence of a visual background. These individuals were also required to estimate their body pointing direction. Menière's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (one week and one month after the operation), and healthy participants were tested at similar times. Unilateral vestibular loss impaired the representation of both the external space and the body pointing direction: in the dark, the configuration of perceived targets was shifted toward the lesioned side and compressed toward the contralesioned hemifield, with higher pointing error in the near space. Performance varied according to the time elapsed after neurotomy: deficits were stronger during the early stages, while gradual compensation occurred subsequently. These findings provide the first demonstration of the critical role of vestibular signals in the representation of external space and of body pointing direction in the early stages after unilateral vestibular loss.

Cochlear implantation through the middle fossa: an anatomic study for a novel technique.

CONCLUSION: The technique proposed is simple, reliable, and provides sufficient exposure of the basal portion of the cochlea while avoiding disabling complications. It enables visualization of the cochlear basal turn and the osseous spiral lamina, facilitating the insertion of the cochlear implant array through the scala tympani. OBJECTIVES: To describe a novel approach for exposing the cochlear basal turn for cochlear implantation through the middle cranial fossa. METHODS: Fifty temporal bones were dissected and a cochleostomy was performed via a middle fossa approach on the most superficial part of the cochlear basal turn, using the superior petrosal sinus, the skeletonized petrous apex, the lateral surface of the meatal plane trailed on the petrous apex from its most proximal portion, and the great superficial petrosal nerve as landmarks. The distance between the landmarks and the distance between the cochleostomy and the round window were measured. RESULTS: In all temporal bones, only the top portion of the cochlear basal turn was uncovered. The cochleostomy allowed both the scala tympani and the vestibule to be exposed. A computed tomography scan of the temporal bones was performed to document the electrode insertion from the cochlear basal turn until its apex. The mean ± SD minor and major distances between the cochleostomy and the meatal plane were estimated to be 2.48 ± 0.88 mm and 3.11 ± 0.86 mm, respectively. The mean distance from the cochleostomy to the round window was 8.38 ± 1.96 mm, and that to the superior petrosal sinus was 9.19 ± 1.59 mm. The mean minor and major distances between the cochleostomy and the long axis of the meatal plane from its most proximal portion were estimated to be 6.63 ± 1.38 mm and 8.29 ± 1.43 mm, respectively.

Static and dynamic posture control in postlingual cochlear implanted patients: effects of dual-tasking, visual and auditory inputs suppression.

Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body's position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI) surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of postlingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static (stable platform) and dynamic (platform in translation) conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO) and eyes closed (EC) conditions, with the CI activated (ON) or not (OFF). Results showed that the postural performance of the CI patients strongly differed from the controls, mainly in the EC condition. The CI patients showed significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk: they behaved dynamically without vision like an inverted pendulum while the controls showed a whole body rigidification strategy. Hearing (prosthesis on) as well as dual-tasking did not really improve the dynamic postural performance of the CI patients. We conclude that CI patients become strongly visual dependent mainly in challenging postural conditions, a result they have to be awarded of particularly when getting older.

Where is straight ahead to a patient with unilateral vestibular loss?

The vestibular system is classically associated with postural control, oculomotor reflexes and self-motion perception. The patients with vestibular loss are primarily concerned with balance and gait problems including head and trunk tilt and walking trajectory deviation to the lesioned side. These long-lasting postural and locomotor biases are thought to originate from changes in spatial perception of self. Indeed, we show here that vestibular cues are necessary for an accurate representation of body orientation. Patients with right (RVN; n=11) or left vestibular neurotomy (LVN; 9) as a treatment for Menière's disease were compared with 10 healthy controls. The subjective straight ahead (SSA) was investigated using a method disentangling lateral shift and tilt components of error. In the horizontal plane, subjects were required to align a rod with their body midline. In the frontal plane, they were asked to align the rod with the midline of head or trunk. The analysis of SSA clearly showed distinct results according to the side of the lesion. The LVN patients had a contralesional lateral shift of SSA. In addition, they showed an ipsilesional tilt, more severe for the head than for the trunk. By contrast, in RVN patients, the representation of the body midline was fairly accurate in both the horizontal and frontal planes and did not differ from that of control subjects. The present study shows deviations in body orientation representation after unilateral vestibular loss. Deviations are observed in the horizontal as well as in the frontal planes. Interestingly, only patients with left vestibular loss were concerned with these changes in perception of self-orientation in space. These data support the hypothesis of an asymmetric vestibular function in healthy subjects and confirm the similarity of functional disorders in patients with vestibular deficits or spatial neglect. For the first time, this similarity is found at the level of body representation.

Postural performance of vestibular loss patients under increased postural threat.

The effects of increasing postural task difficulty on balance control was investigated in 9 compensated vestibular loss patients whose results were compared to 11 healthy adults. Subjects were tested in static (stable support) and dynamic (sinusoidal translation of the support) conditions, both at floor level and at height (62 cm above the floor), and with and without vision, to create an additional postural threat. Wavelet analysis of the center of foot pressure displacement and motion analysis of the body segments were used to evaluate the postural performance. Evaluation questionnaires were used to examine the compensation level of the patients (DHI test), their general anxiety level (SAST), fear of height (subjective scale), and workload (NASA TLX test). (Vestibular loss patients rely more on vision and spend more energy maintaining balance than controls, but they use the same postural strategy as normals in both static and dynamic conditions.) Questionnaire data all showed differences in behavior and perceptions between the controls and the patients. However, at height and without vision, a whole body strategy leading to rigid posture replaces the head stabilization strategy found for standing at floor level. The effects of height on postural control can be attributable to an increase in postural threat and attention changes resulting from modifications in perception.

Cochlear implantation and contralateral auditory brainstem implantation.

OBJECTIVE: Report outcomes of 2 first known cases using a cochlear implant (CI) and a contralateral auditory brainstem implant (ABI). PATIENTS: Two adult patients with postlingual sensorineural deafness. INTERVENTION: Both patients had unilateral CI insertion followed by contralateral ABI insertion. In 1 case, there was a large left vestibular schwannoma in the only hearing left ear. CI insertion was first performed in the right longstanding deaf ear. Shortly afterward during the left translabyrinthine surgery, a left ABI was simultaneously inserted. The second patient had Ménière's disease controlled initially by right translabyrinthine vestibular neurectomy but complicated by a right dead ear. When symptoms recurred she underwent left retrosigmoid vestibular neurectomy with auditory nerve preservation. This allowed left CI insertion and a subsequent right ABI insertion. MAIN OUTCOME MEASURES: Pure tone audiometry (PTA), speech discrimination in quiet (SDq), speech discrimination in noise (SDn), and sound localization. Testing was performed with the following: 1) ABI activated alone, 2) CI activated alone, 3) CI and ABI activation (CI-ABI), and 4) CI linked to a contralateral routing of sound (CROS) hearing aid system (CI-CROS). Quality of life assessments were made using a validated questionnaire. RESULTS: PTA was worst with the ABI activated alone. SDq was best with the CI-CROS. Regarding SDn with noise coming from the CI side, the head shadow effect was only overcome by the CI-ABI; however, the CI-CROS worked best in the presence of noise opposite to the CI. The CI activated alone and CI-ABI produced useful sound localization. Quality-of-life assessments were best with the CI-CROS. CONCLUSION: Bilateral sound detection seems more beneficial than unilateral in profoundly deaf cases with only 1 functioning auditory nerve. A CI-CROS may produce similar gains to a CI-ABI.

Vestibular information is necessary for maintaining metric properties of representational space: evidence from mental imagery.

The vestibular system contributes to a wide range of functions, from postural and oculomotor reflexes to spatial representation and cognition. Vestibular signals are important to maintain an internal, updated representation of the body position and movement in space. However, it is not clear to what extent they are also necessary to mentally simulate movement in situations that do not involve displacements of the body, as in mental imagery. The present study assessed how vestibular loss can affect object-based mental transformations (OMTs), i.e., imagined rotations or translations of objects relative to the environment. Participants performed one task of mental rotation of 3D-objects and two mental scanning tasks dealing with the ability to build and manipulate mental images that have metric properties. Menière's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (1 week and 1 month). They were compared to healthy participants tested at similar time intervals and to bilateral vestibular-defective patients tested after the recovery period. Vestibular loss impaired all mental imagery tasks. Performance varied according to the extent of vestibular loss (bilateral patients were frequently the most impaired) and according to the time elapsed after unilateral vestibular neurotomy (deficits were stronger at the early stage after neurotomy and then gradually compensated). These findings indicate that vestibular signals are necessary to perform OMTs and provide the first demonstration of the critical role of vestibular signals in processing metric properties of mental representations. They suggest that vestibular loss disorganizes brain structures commonly involved in mental imagery, and more generally in mental representation.

Engraftment of human nasal olfactory stem cells restores neuroplasticity in mice with hippocampal lesions.

Stem cell-based therapy has been proposed as a potential means of treatment for a variety of brain disorders. Because ethical and technical issues have so far limited the clinical translation of research using embryonic/fetal cells and neural tissue, respectively, the search for alternative sources of therapeutic stem cells remains ongoing. Here, we report that upon transplantation into mice with chemically induced hippocampal lesions, human olfactory ecto-mesenchymal stem cells (OE-MSCs) - adult stem cells from human nasal olfactory lamina propria - migrated toward the sites of neural damage, where they differentiated into neurons. Additionally, transplanted OE-MSCs stimulated endogenous neurogenesis, restored synaptic transmission, and enhanced long-term potentiation. Mice that received transplanted OE-MSCs exhibited restoration of learning and memory on behavioral tests compared with lesioned, nontransplanted control mice. Similar results were obtained when OE-MSCs were injected into the cerebrospinal fluid. These data show that OE-MSCs can induce neurogenesis and contribute to restoration of hippocampal neuronal networks via trophic actions. They provide evidence that human olfactory tissue is a conceivable source of nervous system replacement cells. This stem cell subtype may be useful for a broad range of stem cell-related studies.