Irreversible Hypoglossal Nerve Injury and Concomitant Trigeminal System Dysfunction After Anterior Surgery to the Cervical Spine: Case Report and Literature Review

Hypoglossal Nerve Neuropathies-Analysis of Causes and Anatomical Background

The hypoglossal nerve is the last, and often neglected, cranial nerve. It is mainly responsible for motor innervation of the tongue and therefore the process of chewing and articulation. However, tumors, aneurysms, dissections, trauma, and various iatrogenic factors such as complications after surgeries, radiotherapy, or airway management can result in dysfunction. Correct differential diagnosis and suitable treatment require a thorough knowledge of the anatomical background of the region. This review presents the broad spectrum of hypoglossal neuropathies, paying particular attention to these with a compressive background. As many of these etiologies are not common and can be easily overlooked without prior preparation, it is important to have a comprehensive understanding of the special relations and characteristic traits of these medical conditions, as well as the most common concomitant disorders and morphological traits, influencing the clinical image. Due to the diverse etiology of hypoglossal neuropathies, specialists from many different medical branches might expect to encounter patients presenting such symptoms.

Recognition of Prodromal Hypoglossal Nerve Palsy Presenting with Neck Pain as Primary Complaint: Findings from a Rare Case Report in Direct Access Physiotherapy during the COVID-19 Pandemic

Neck pain (NP) is the second most common musculoskeletal disorder. Spinal cysts (SCs) are cystic dilatations of the synovial sheaths in joints and tendons. SCs are extremely rare in the cervical spine. Typically, patients are unaware of having an SC due to its asymptomatic nature; however, when cervical SC extends, its volume could compress the surrounding structures, such as the hypoglossal nerve. Isolated hypoglossal nerve palsy (HNP) is very rare and typically presents with unilateral atrophy of the musculature of the tongue and contralateral tongue deviation. Often, patients with HNP also report occipital/neck pain. A 75-year-old man with occipital/neck pain as a primary complaint. Although difficult to observe because of the filtering facepiece two mask, difficulties in articulation and sialorrhea during the interview were noticed. These latter were cues to consider CN examination that revealed CN XII palsy. This prompted a referral for further examination that revealed an SC compressing the right hypoglossal canal. The patient was not considered a surgical candidate and was managed conservatively. This case report outlines the relevant findings relating to the triage of a rare isolated hypoglossal nerve palsy from the physiotherapist's perspective within a complex setting because of the COVID-19 pandemic. Although referred with a diagnosis of cervical radiculopathy, our case highlights that skilled physiotherapists may play a fundamental role in both the recognition and, when applicable, subsequent novel management of a non-musculoskeletal presentation.

How to Avoid Misdiagnosing Spontaneous Cervical Spinal Epidural Hematoma as Ischemic Stroke: 3 Case Reports and Literature Review

When spontaneous cervical spinal epidural hematoma (SCEH) presents with hemiparesis, it can be misdiagnosed with ischemic stroke (IS), and the treatment of IS such as thrombolysis may deteriorate the symptoms of patients with SCEH, leading to worse sequelae or even death. We reported 3 SCEH patients who were initially suspected as IS in our center between Jun 2020 and April 2022 and analyzed their clinical characteristics together with 48 patients reported in the literature from Jan 1995 to April 2022. Two of the 3 SCEH patients had neck symptoms, while none of them presented cranial nerve symptoms. Cranial computed tomography (CT) scans were negative; however, abnormal signals in the cervical spinal canal were observed during cranial computed tomography angiography (CTA) and subsequent cervical CT confirmed the diagnosis of SCEH. All of them avoid mistreatment with recombinant tissue plasminogen activator (rt-PA). Subsequently, we analyzed the clinical characteristics of a total of 51 patients. Thirteen of them developed symptoms during activity. Neck pain was an important sign of SCEH because 35 patients had neck pain or neck discomfort. Sensory impairment was reported in a small proportion of patients (11/51), which varied a lot in the patients. Some special manifestations highly suggested spinal cord lesions and provided evidence for the early differential diagnosis of SCEH and stroke, but the incidence of which was quite low: ipsilateral Horner syndrome in 2 patients, Brown-Séquard syndrome in 2 cases, and Lhermitte's sign in 1 case. Only a minority (8/51) of the patients were correctly diagnosed at the emergency unit using cervical CT. Six patients were correctly diagnosed when performing CTA. A large portion of the cases (21/51) were first misdiagnosed as IS, but no responsible lesions were found on cranial magnetic resonance imaging (MRI), and subsequent cervical MRI confirmed the diagnosis. Sixteen patients were diagnosed with SCEH after the deterioration of symptoms. A total of 13 patients received rt-PA, and 10 of them had symptoms aggravation after thrombolysis. For patients with acute onset of hemiparesis but without cranial nerve symptoms, especially those accompanied by clinical features such as neck pain, ipsilateral Horner syndrome, Brown-Séquard syndrome, and Lhermitte's sign, SCEH should be highly suspected rather than stroke. Careful differential diagnosis should be performed with a comprehensive medical history and thorough physical examination. Cervical CT scan is a reasonable choice for quick differential diagnosis prior to administering potentially harmful therapy, especially rt-PA.

Long latency responses in tongue muscle elicited by various stimulation sites in anesthetized humans - New insights into tongue-related brainstem reflexes

BACKGROUND

Long Latency Responses (LLR) in tongue muscles are a scarcely described phenomenon, the physiology of which is uncertain.

OBJECTIVES

The aim of this exploratory, observational study was to describe tongue-LLR elicited by direct trigeminal nerve (DTNS), dorsal column (DoColS), transcranial electric (TES) and peripheral median nerve (MNS) stimulation in a total of 93 patients undergoing neurosurgical procedures under general anesthesia.

METHODS

Bilateral tongue responses were derived concurrently after each of the following stimulations: (1) DTNS applied with single monophasic or train-of-three pulses, ≤5 mA; (2) DoColS applied with a train-of-three pulses, ≤10 mA; (3) TES consisting of an anodal train-of-five stimulation, ≤250 mA; (4) MNS at wrist consisting of single or train-of-three monophasic pulses, ≤50 mA. Polyphasic tongue muscle responses exceeding the latencies of tongue compound muscle action potentials or motor evoked potentials were classified as LLR.

RESULTS

Tongue-LLR were evoked from all stimulation sites, with latencies as follows: (1) DTNS: solely ipsilateral 20.2 ± 3.3 msec; (2) DoColS: ipsilateral 25.9 ± 1.6 msec, contralateral 25.1 ± 4.2 msec; (3) TES: contralateral 55.3 ± 10.2 msec, ipsilateral 54.9 ± 12.0 msec; (4) MNS: ipsilateral 37.8 ± 4.7 msec and contralateral 40.3 ± 3.5 msec.

CONCLUSION

The tongue muscles are a common efferent in brainstem pathways targeted by trigeminal and cervical sensory fibers. DTNS can elicit the "trigemino-hypoglossal-reflex". For the MNS elicited tongue-LLR, we propose the term "somatosensory-evoked tongue-reflex". Although the origin of the TES related tongue-LLR remains unclear, these data will help to interpret intraoperative tongue recordings.