Risk of sudden death during sleep in syringomyelia and syringobulbia

Revision Thoracic Syringo-Subarachnoid Shunt for Recurrent Syrinx With Syringobulbia: Technique and Surgical Video

Syringomyelia and syringobulbia continue to remain a diagnosis without widely accepted treatment paradigms. Furthermore, the currently available treatment options can be complicated by delayed symptom recurrence and the need for revision surgery. Revision intradural surgery is challenging, and currently, there is a paucity of literature describing safe techniques for revision syringotomy and shunt placement. In this technical report, we present a surgical video describing the technique of revision syringo-subarachnoid shunt placement in a 61-year-old female with a history of multiple intradural surgeries who presented with progressively symptomatic ascending syringobulbia. 

Syringobulbia in Patients with Chiari Malformation Type I: A Systematic Review

This study aimed to summarize the clinical features, diagnosis, and treatment of Chiari malformation type I- (CM-1-) associated syringobulbia. We performed a literature review of CM-1-associated syringobulbia in PubMed, Ovid MEDLINE, and Web of Science databases. Our concerns were the clinical features, radiologic presentations, treatment therapies, and prognoses of CM-1-associated syringobulbia. This review identified 23 articles with 53 cases. Symptoms included headache, neck pain, cranial nerve palsy, limb weakness/dysesthesia, Horner syndrome, ataxia, and respiratory disorders. The most frequently involved area was the medulla. Most of the patients also had syringomyelia. Surgical procedures performed included posterior fossa decompression, foramen magnum decompression, cervical laminectomy, duraplasty, and syringobulbic cavity shunt. Most patients experienced symptom alleviation or resolution postoperatively. A syringobulbic cavity shunt provided good results in refractory cases. Physicians should be aware of the possibility of syringobulbia in CM-1 patients, especially those with symptoms of sudden-onset brain-stem involvement. The diagnosis relies on the disorder's specific symptomatology and magnetic resonance imaging. Our review suggests that the initial therapy should be posterior fossa decomposition with or without duraplasty. In refractory cases, additional syringobulbic cavity shunt is the preferred option.

A Conditional Inference Tree Model for Predicting Sleep-Related Breathing Disorders in Patients With Chiari Malformation Type 1: Description and External Validation

STUDY OBJECTIVES

The aim of this study is to generate and validate supervised machine learning algorithms to detect patients with Chiari malformation (CM) 1 or 1.5 at high risk of the development of sleep-related breathing disorders (SRBD) using clinical and neuroradiological parameters.

METHODS

We prospectively included two independent datasets. A training dataset (n = 90) was used to obtain the best model, whereas a second dataset was used to validate it (n = 74). In both cohorts, the same clinical, neuroradiological, and sleep studies were carried out. We used two supervised machine learning approaches, multiple logistic regression (MLR) and the unbiased recursive partitioning technique conditional inference tree (URP-CTREE), to detect patients at high risk of SRBD. We then compared the accuracy, sensitivity, and specificity of the two prediction models.

RESULTS

Age (odds ratio [OR] 1.1 95% confidence interval [CI] 1.05-1.17), sex (OR 0.19 95% CI 0.05-0.67), CM type (OR 4.36 95% CI 1.14-18.5), and clivus length (OR 1.14 95% CI 1.01-1.31) were the significant predictor variables for a respiratory disturbance index (RDI) cutoff that was ≥ 10 events/h using MLR. The URP-CTREE model predicted that patients with CM-1 who were age 52 years or older and males with CM-1 who were older than 29 years had a high risk of SRBD. The accuracy of predicting patients with an RDI ≥ 10 events/h was similar in the two cohorts but in the URP-CTREE model, specificity was significantly greater when compared to MLR in both study groups.

CONCLUSIONS

Both MLR and URP-CTREE predictive models are useful for the diagnosis of SRBD in patients with CM. However, URP-CTREE is easier to apply and interpret in clinical practice.

Charles Prosper Ollivier d'Angers (1796-1845) and his contributions to defining syringomyelia

INTRODUCTION

Distinguished as an anatomist, pathologist, and clinician, the Frenchman Charles Prosper Ollivier d'Angers dedicated his life to accelerating the forefront of neuroscience. At a young age, he explored the diseases and disorders of the spinal cord during a time when clinical neurological investigation scarcely existed. Ollivier d'Angers coined the term "syringomyelia."

CONCLUSION

The coinage of the term syringomyelia by d'Angers shed light on the disorder causing more practitioners to investigate the spinal cord and its defects.

Sleep apnea and REM sleep behavior disorder in patients with Chiari malformations

BACKGROUND: Chiari malformations (CM) may result in the appearance of REM sleep behavior disorder (RBD) and sleep apnea syndrome (SAS) that can be considered markers of brain stem dysfunction. PURPOSE: To evaluate the frequency of RBD and SAS in patients with CM type I and II. METHOD: Were evaluated 103 patients with CM by means of full night polysomnography. Were scoring different sleep stages, frequency of abnormal movements (through video monitoring) and abnormal respiratory events. RESULTS: Of the 103 patients, 36 showed CM type I and 67 CM type II. Episodes of RBD were observed in 23 patients. Abnormal apnea-hypopnea index (AHI) was observed in 65 patients. CONCLUSION: The high rate of RBD suggests that this parassomnia and the increased frequency of central sleep apnea episodes, may be considered as a marker of progressive brain stem dysfunction.

Hindbrain-hernia-related syringomyelia without syringobulbia, complicated by permanent nocturnal central hypoventilation requiring non-invasive ventilation

INTRODUCTION

In the absence of syringobulbia, hindbrain hernia does not commonly cause permanent respiratory complications. We present two patients who developed permanent central nocturnal hypoventilation following acute deterioration of hindbrain-hernia-related syringomyelia despite successful surgery.

PATIENTS

Two children (one boy and one girl, aged 7 and 13 years, respectively) presented with acute neurological deterioration. The boy presented with a 6-week history of progressive tiredness and weakness and a short history of respiratory depression. The girl presented with a 2-year history of left hemiparesis and a short history of left hemiplegia and respiratory depression. On magnetic resonance scan, both had hindbrain hernia, hydrocephalus and cervical syringomyelia. Following cranio-vertebral decompression and, later, a ventriculoperitoneal shunt, the syringomyelia remained well controlled in both patients. In contrast, their respiratory depression improved minimally. Repeated multichannel respiratory monitoring revealed a persistently slow sleeping respiratory rate, with nocturnal hypercapnia and hypoxemia, managed successfully by night-time non-invasive ventilation. Neither the boy nor the girl, after 7 and 4 years, respectively, has developed any complications of nocturnal hypoventilation. When awake, both breathe normally.

RESULT

Both children appear to have suffered a permanent impairment of respiratory control, resulting in nocturnal hypoventilation. This is usually seen with brain stem lesions and is unexpected when syringomyelia does not extend above C2, in the absence of syringobulbia.

DISCUSSION

Central nocturnal hypoventilation is postulated to be due to permanent damage of central brain stem pathways controlling the respiratory muscles, due to local pressure at the cranio-cervical junction associated with acute deterioration of the hindbrain herniation.

CONCLUSION

Sudden deterioration of hindbrain hernia and cervical syringomyelia can rarely impair the central mechanisms of respiratory control, with long-term implications on quality of life.

Adult Chiari malformation and sleep apnoea

Chiari malformation (CM) is primarily characterised by herniation of the cerebellar tonsils through the foramen magnum. Clinically, two main types of CM represent the vast majority of cases: type I (in adults) and type II (in infants). CM may result in neuronal impairment of the brainstem, upper spinal cord and cranial nerves. Part of the afferent and efferet systems and the central respiratory controlling system are located in the cranium-cervical transition and may be damaged in these pathologies, leading to respiratory disorders, such as respiratory failure and death. The ventilatory responses to exogenous and endogenous stimuli, such as responses to hypoxia and hypercapnia, are usually diminished, and apnea may be manifested and detected during sleep, allowing for the diagnosis. This study is a review of the relationship between sleep apnoea and adult CM.

Syringomyelia with syringobulbia presenting only with paralysis of 9th and 10th cranial nerves

We report a case of syringomyelia with syringobulbia, in a patient who presented only with involvement of the 9th and 10th cranial nerves.

Central chemosensitivity and breathing asleep in unilateral medullary lesion patients: comparisons to animal data

The rostro-ventrolateral medulla (RVLM) is a site of chemosensitivity in animals; such site(s) have not been defined in humans. We studied the effect of unilateral focal lesions in the rostrolateral medulla (RLM) of man, on the ventilatory CO(2) sensitivity and during awake and sleep breathing. Nine patients with RLM lesions (RLM group), and six with lesions elsewhere (non-RLM group) were studied. The ventilatory CO(2) sensitivity was lower in the RLM compared with the non-RLM group (mean (S.D.), RLM, 1.4 (0.9), non-RLM 3.0 (0.6) L min(-1) mmHg(-1)). In both groups resting breathing was normal. During sleep all RLM patients had frequent arousals, four had significant sleep disordered breathing (SDB), only one non-RLM patient had SDB. Our findings in humans resemble those in animals with focal RVLM lesions. This review provides evidence that in humans there is an area of chemosensitivity in the RLM. We propose that in humans, dorsal displacement of the RVLM area of chemosensitivity in animals, arises from development of the olive plus the consequences of the evolution of the cerebellum/inferior peduncle.

Complete spontaneous resolution of childhood Chiari I malformation and associated syringomyelia

The diagnosis of Chiari I malformation and associated syringomyelia is often made in childhood. Since the advent of magnetic resonance imaging, these abnormalities are increasingly detected incidentally. Despite incomplete understanding of the natural history of asymptomatic Chiari I malformations, the current recommendation is to consider prophylactic surgical intervention in those with an associated syringomyelia. This case report presents a complete spontaneous resolution of a Chiari I malformation and syringomyelia in a child. It illustrates the possibility that asymptomatic children with Chiari I malformations and syringomyelia may be followed conservatively.

Respiratory disturbances during sleep in syringomyelia and syringobulbia

OBJECTIVE

To determine the frequency and types of abnormalities of respiratory control during sleep in syringomyelia and syringobulbia and to provide a basis to predict patients at risk of sudden death.

METHODS

Thirty patients (15 male and 15 female; mean age 39.0 +/- 12.6 years) with communicating syringomyelia were divided into two groups: those with evidence of syringobulbia (17 patients) and those without compromise of the medulla or syringomyelia (13 patients). Patients were studied with pulmonary function studies and polysomnography. Respiratory center sensitivity to CO2 (rebreathing technique) was measured in 9 patients.

RESULTS

Severely affected patients had mild-to-moderate restriction and individual patients had bilateral diaphragmatic or vocal cord palsy, abnormal respiratory rhythm, prolonged inspiratory time, or an abnormal respiratory response to CO2. Very prolonged central, obstructive, and mixed sleep apneas with low O2 saturation values and a fixed heart rate were recorded in most patients with syringobulbia. Five patients developed severe respiratory complications and died during a follow-up period of 10 years. Respiratory abnormalities failed to correlate with syrinx size.

CONCLUSIONS

Severe abnormalities in respiratory rhythm generation during sleep occur in patients with syringobulbia. The respiratory disturbances are not due to muscle weakness and they are not correlated with the size of the cavity. The combination of dysphagia and dysphonia in patients with longstanding syringomyelia and syringobulbia predicted likelihood of respiratory disturbances during sleep.

Involuntary movements and abnormal spontaneous EMG activity in syringomyelia and syringobulbia

OBJECTIVE

To describe different types of involuntary movements and abnormal spontaneous electromyographic (EMG) activity in patients with syringomyelia.

BACKGROUND

A comprehensive study on involuntary movements in patients with syringomyelia has not yet been undertaken, to these authors' knowledge.

METHODS

One hundred adult patients with syringomyelia were examined over the last 15 years. Involuntary movements were videotaped and evaluated by two independent observers. Electromyographic recordings were made using bipolar surface electrodes. The H-reflex recovery curve was obtained after stimulation of the median nerve at the elbow and recording from the flexor carpi radialis.

RESULTS

Involuntary movements or abnormal postures were observed in 22 patients. Three patients showed segmental spinal myoclonus, nine minipolymyoclonus, and four propriospinal myoclonus. Five patients had unilateral or bilateral hand postural tremor (8-10 Hz). Focal or segmental dystonia was observed in three patients. Electromyography showed spontaneous bursts of grouped action potentials synchronous in muscles innervated by the same spinal segment, synchronous firing of neurogenic motor unit potentials, or continuous motor unit activity. Increased H-reflex responses to conditioning stimuli were found in patients with spinal myoclonus. Long latency responses were obtained during peripheral nerve stimulation in four patients. Four patients had rigidity and abnormal upper limb posture. Respiratory synkinesis was observed in three patients. One patient developed inverse masticatory muscle activity.

CONCLUSIONS

Patients with syringomyelia showed a wide spectrum of involuntary movements. An increased excitability of spinal motor neurons was probably the basic underlying mechanism.

Applying classifications of sleep disorders to children with neurologic conditions

Information concerning sleep ontogeny and sleep disorders in children is required by many pediatric specialists. Pediatric neurologists, for instance, frequently are called upon to assist in the evaluation of children with undiagnosed symptoms and signs during sleep, as well as to care for children and adolescents with specific neurologic diseases who also experience sleep disturbances. This review discusses pediatric sleep disturbances with specific reference to sleep in children with neurologic conditions.

Obstructive sleep apnea and related disorders

OSAS, a common cause of disrupted sleep and EDS, result from repetitive closure of the upper airway during sleep. It probably represents the most severe syndrome related to obstruction of the upper airway; less severe forms include UARS, a syndrome characterized by the need for increased effort to breath but no prominent apneas or hypopneas, and primary snoring. Initial clues to the presence of OSAS and related disorders are derived from the history and include loud snoring, EDS or insomnia, and witnessed apneas. Some patients, especially women, may complain mostly of tiredness or fatigue, and children may present with behavioral abnormalities. Obesity, a large neck circumference, and a crowded oropharynx are common on physical examination. Nonobese patients, in particular, often have retrognathia, a high-arched narrow palate, macroglossia, enlarged tonsils, temporomandibular joint abnormalities, or chronic nasal obstruction. The clinical suspicion of obstructed nocturnal breathing is confirmed by overnight polysomnography, and an MSLT may be used to assess sleepiness. Esophageal manometry during polysomnography facilitates diagnosis of UARS. Treatment most commonly consists of nasal CPAP or BPAP, although problems with compliance make surgical treatment preferable in some cases. Although UPPP eliminates sleep apnea only in a minority of patients, combining UPPP with maxillofacial procedures appears to improve outcomes. Other treatments such as the use of dental appliances or medications, weight loss, and positional therapy may be useful as adjunctive therapy for moderate to severe OSAS or as primary treatments for UARS or mild OSAS.

Significance of chronic tonsillar herniation in sudden death

The Chiari I malformation is a congenital abnormality of the cerebellum strongly associated with syringomyelia and also associated with bony abnormalities of the base of the skull and the cervical spine. This review examines the case of a 25 year old man who collapsed and died following a blow to the face and was found at post mortem to have a Chiari I malformation and syringomyelia but no gross or microscopic evidence of fresh brain or spinal cord injury. The occurrence of sudden and unexpected deaths in this condition is discussed especially in the context of apparently minor coincident trauma.

Multifactorial obstructive sleep apnea in a patient with Chiari malformation

We report a patient with severe obstructive sleep apnea (OSA) associated with a unique combination of syringobulbia-myelia, Chiari malformation type I (CM), absent hypoxic ventilatory drive, vocal cord paralysis, post-menopausal status, obesity, and acute respiratory failure necessitating mechanical ventilation. The remote onset of OSA five years after surgery underscores the need for long-term follow-up of patients with syringobulbia-myelia and CM and the importance of addressing multiple interacting neurologic, metabolic, and mechanical predispositions to sleep-disordered breathing.

The central autonomic network: functional organization, dysfunction, and perspective

The central autonomic network (CAN) is an integral component of an internal regulation system through which the brain controls visceromotor, neuroendocrine, pain, and behavioral responses essential for survival. It includes the insular cortex, amygdala, hypothalamus, periaqueductal gray matter, parabrachial complex, nucleus of the tractus solitarius, and ventrolateral medulla. Inputs to the CAN are multiple, including viscerosensory inputs relayed on the nucleus of the tractus solitarius and humoral inputs relayed through the circumventricular organs. The CAN controls preganglionic sympathetic and parasympathetic, neuroendocrine, respiratory, and sphincter motoneurons. The CAN is characterized by reciprocal interconnections, parallel organization, state-dependent activity, and neurochemical complexity. The insular cortex and amygdala mediate high-order autonomic control, and their involvement in seizures or stroke may produce severe cardiac arrhythmias and other autonomic manifestations. The paraventricular and other hypothalamic nuclei contain mixed neuronal populations that control specific subsets of preganglionic sympathetic and parasympathetic neurons. Hypothalamic autonomic disorders commonly produce hypothermia or hyperthermia. Hyperthermia and autonomic hyperactivity occur in patients with head trauma, hydrocephalus, neuroleptic malignant syndrome, and fatal familial insomnia. In the medulla, the nucleus of the tractus solitarius and ventrolateral medulla contain a network of respiratory, cardiovagal, and vasomotor neurons. Medullary autonomic disorders may cause orthostatic hypotension, paroxysmal hypertension, and sleep apnea. Neurologic catastrophes, such as subarachnoid hemorrhage, may produce cardiac arrhythmias, myocardial injury, hypertension, and pulmonary edema. Multiple system atrophy affects preganglionic autonomic, respiratory, and neuroendocrine outputs. The CAN may be critically involved in panic disorders, essential hypertension, obesity, and other medical conditions.