Paroxysmal apnea and vasomotor instability following medullary infarction

Stroke-Heart Syndrome: Recent Advances and Challenges

After ischemic stroke, there is a significant burden of cardiovascular complications, both in the acute and chronic phase. Severe adverse cardiac events occur in 10% to 20% of patients within the first few days after stroke and comprise a continuum of cardiac changes ranging from acute myocardial injury and coronary syndromes to heart failure or arrhythmia. Recently, the term stroke–heart syndrome was introduced to provide an integrated conceptual framework that summarizes neurocardiogenic mechanisms that lead to these cardiac events after stroke. New findings from experimental and clinical studies have further refined our understanding of the clinical manifestations, pathophysiology, and potential long‐term consequences of the stroke–heart syndrome. Local cerebral and systemic mediators, which mainly involve autonomic dysfunction and increased inflammation, may lead to altered cardiomyocyte metabolism, dysregulation of (tissue‐resident) leukocyte populations, and (micro‐) vascular changes. However, at the individual patient level, it remains challenging to differentiate between comorbid cardiovascular conditions and stroke‐induced heart injury. Therefore, further research activities led by joint teams of basic and clinical researchers with backgrounds in both cardiology and neurology are needed to identify the most relevant therapeutic targets that can be tested in clinical trials.

Anatomic and MRI bases for medullary infarctions with patients' presentation

OBJECTIVE

There is a low incidence of the medullary infarctions and sparse data about the vascular territories, as well as a correlation among the anatomic, magnetic resonance imaging (MRI) and neurologic signs.

MATERIALS AND METHODS

Arteries of the 10 right and left sides of the brain stem were injected with India ink, fixed in formalin and microdissected. The enrolled 34 patients with medullary infarctions underwent a neurologic, MRI and Doppler examination.

RESULTS

Four types of the infarctions were distinguished according to the involved vascular territories. The isolated medial medullary infarctions (MMIs) were present in 14.7%. The complete MMIs comprised one bilateral infarction (2.9%), whilst the incomplete and partial MMIs were observed in 5.9% and 8.9%, respectively. The anterolateral infarctions (ALMIs) were very rare (2.9%). The complete and incomplete lateral infarctions (LMIs), noted in 35.3%, comprised 11.8% and 23.6%, respectively, that is, the anterior (5.9%), posterior (8.9%), deep (2.9%), and peripheral (5.9%). Dorsal ischemic lesions (DMIs) occurred in 11.8%, either as a complete (2.9%), or isolated lateral (5.9%) or medial infarctions (2.9%). The remaining ischemic regions belonged to various combined infarctions of the MMI, ALMI, LMI and DMI (35.3%). The infarctions most often affected the upper medulla (47.1%), middle (11.8%), or both (29.5%). Several motor and sensory signs were manifested following infarctions, including vestibular, cerebellar, ocular, sympathetic, respiratory and auditory symptoms.

CONCLUSIONS

There was a good correlation among the vascular territories, MRI ischemia features, and neurologic findings regarding the medullary infarctions.

Sinus arrest following acute lateral medullary infarction

Lateral medullary syndrome (LMS) is an ischemic stroke of the medulla oblongata that involves the territory of the posterior inferior cerebellar artery. LMS is often missed as the cause of autonomic dysregulation in patients with recent brain stem stroke. Due to the location of the nucleus tractus solitarius (NTS), the dorsal vagal nucleus, and the nucleus ambiguous in the lateral medulla oblongata, patients with LMS occasionally have autonomic dysregulation–associated clinical manifestations. We report a case of LMS-associated autonomic dysregulation. The case presented by recurrent syncope, requiring permanent pacemaker placement. This case shows the importance of recognizing LMS as a potential cause of life-threatening arrhythmias, heart block, and symptomatic bradycardia. Extended cardiac monitoring should be considered for patients with medullary strokes.

Stroke and breathing

Stroke remains a leading cause of neurologic disability with wide ranging effects, including a variety of respiratory abnormalities. Stroke may influence the central control of the respiratory drive and breathing pattern, airway protection and maintenance, and the respiratory mechanics of inspiration and expiration. In the acute phase of stroke, the central control of breathing is affected by changes in consciousness, cerebral edema, and direct damage to brainstem respiratory centers, resulting in abnormalities in respiratory pattern and loss of airway protection. Common acute complications related to respiratory dysfunction include dysphagia, aspiration, and pneumonia. Respiratory control centers are located in the brainstem, and brainstem stroke causes specific patterns of respiratory dysfunction. Depending on the exact location and extent of stroke, respiratory failure may occur. While major respiratory abnormalities often improve over time, sleep-disordered breathing remains common in the subacute and chronic phases and worsens outcomes. Respiratory mechanics are impaired in hemiplegic or hemiparetic stroke, contributing to worse cardiopulmonary health in stroke survivors. Interventions to address the respiratory complications are under researched, and further investigation in this area is critical to improving outcomes among stroke survivors.

A case of lateral medullary infarction with severe dysphagia and worsening of respiratory failure in the chronic phase of recovery

Patients with lateral medullary infarction (LMI) sometimes present with respiratory failure in the acute or subacute phase. We experienced a LMI patient with progression of respiratory failure that required bilevel positive airway pressure in the chronic phase. LMI patients must be carefully observed even in the chronic phase of recovery.

Lateral medullary infarction with cardiovascular autonomic dysfunction: an unusual presentation with review of the literature

PURPOSE

We report an unusual case of lateral medullary infarction presenting with orthostatic hypotension with pre-syncope without vertigo or Horner's syndrome.

METHODS

Case report with review of the literature.

RESULTS

A 67-year-old man presented with pre-syncope and ataxia without vertigo. Initial brain CT and MRI were normal. Neurological evaluation revealed right-beating nystagmus with left gaze, vertical binocular diplopia, right upper-extremity dysmetria, truncal ataxia with right axial lateropulsion, and right-facial and lower extremity hypoesthesia. Bedside blood pressure measurements disclosed orthostatic hypotension. He had normal sinus rhythm on telemetry and normal ejection fraction on echocardiogram. A repeat brain MRI disclosed an acute right dorsolateral medullary infarct. Autonomic testing showed reduced heart rate variability during paced deep breathing, attenuated late phase II and phase IV overshoot on Valsalva maneuver, and a fall of 25 mmHg of blood pressure at the end of a 10-min head-up tilt with no significant change in heart rate. These results were consistent with impaired sympathetic and parasympathetic cardiovascular reflexes. He was discharged to acute rehabilitation a week later with residual right dysmetria and ataxia.

CONCLUSION

Lateral medullary infarctions are usually reported as partial presentations of classical lateral medullary syndrome with accompanying unusual symptoms ranging from trigeminal neuralgias to hiccups. Pre-syncope from orthostatic hypotension is a rare presentation. In the first 3-4 days, absence of early DWI MRI findings is possible in small, dorsolateral medullary infarcts with sensory disturbances. Physicians should be aware of this presentation, as early diagnosis and optimal therapy are associated with good prognosis.

Distributive shock, cardiac arrhythmias and multiple organ failure following surgery of a fourth ventricular epidermoid

A 33-years-old male patient presented with cardiac arrhythmias, acute shock and multiple organ dysfunction after the surgical removal of a massive epidermoid posterior to the brainstem. The patient initially presented with paraesthesia along the right C6 dermatome due to a big tumour at the brain stem. Surgical removal was performed without adverse events and he was transferred to our intensive care unit (ICU) immediately after the operation. Though initially showing a stable postsurgical course he developed cardiac arrhythmias and a state of acute distributive shock with consecutive multi organ failure. Extensive diagnostic measures could not identify a specific cause for this rapid deterioration. However, under carefully monitored symptomatic therapy the patient improved quickly, was extubated 72 h after admission and discharged from the ICU 6 days later. The follow-up did not show any persisting neurological deficits and no evidence of a residual tumour in the MRI-study.

Medicine in the future - with subspecialists in medullary neurology and brain dentistry

The solitary tract nucleus of the medulla with its limited watershed vascular capacity may occasionally be the focus of transient ischemia caused by the increased metabolic demands associated with frequent and intense neuronal stimulation from other organs and other parts of the brain. Case reports have suggested that these ischemic changes may sometimes result in the initiation of intense autonomic discharges, which can occasionally be fatal. Therapeutic interventions for the medulla oblongata are hampered by its limited accessibility. Systemically administered pharmaceuticals may have some usefulness in future years. Previous experience with vagus nerve stimulation in the treatment of epilepsy suggests that it may have some usefulness in stabilizing medullary autonomic discharges. Computerized electronic stimulation of other cranial nerves may be helpful as well, especially the chorda tympani nerve, and may be most easily accomplished from implanted dental appliances, especially molar modules, transmitting signals via secondary transmitters procedurally placed on cranial nerves. Future technology may enable wireless signaling from the implanted dental appliance to the secondary transmitter placed at the nerve site. By the year 2050 subspecialists in medullary neurology and brain dentistry may use computerized electronic stimulation of cranial nerves to prevent sudden unexpected death and treat “chest pain from the brain”.

Dynamic changes in sleep-related breathing abnormalities in bilateral paramedian mesencephalon and thalamus stroke: a follow-up case study

BACKGROUND

Bilateral paramedian thalamic stroke is characterized by hypersomnia, vertical gaze palsy, amnestic alteration, and apathic state. Combined lesion of the paramedian thalamus and mesencephalon bilaterally is extremely rare. Little is known about the breathing disturbances of the particular region due to the lesion. The following describes the specific case of a woman, age 62, with bilateral paramedian thalamic and mesencephalic stroke. Initially, the patient's complaints exhibited altered vigilance and vertical gaze palsy. Notably, following the acute phase, fluctuating hypersomnia was detected. The MRI (brain) revealed an ischemic lesion in the medial part of the mesencephalon and paramedian thalamus, bilaterally.

AIMS

The aim of the present study is to elucidate the involvement and characteristics of sleep-related breathing abnormalities in the clinical manifestation of the combined paramedian thalamic and mesencephalic stroke.

METHODS

Polysomnographic recordings were accomplished seven times with 1-week interval between the consecutive recordings, toward investigating the early changes of sleep and sleep-related breathing abnormalities.

RESULTS

Sleep structure examination featured a decrease in N3 and REM ratio and an increase in N1 and N2 ratio with minimal improvement during the recovery period. In contrast, significant changes were found in the breathing pattern: the initial central apnea dominance was followed by obstructive apneas with a gradual decrease of the total pathological respiratory events.

CONCLUSION

In addition to the structural abnormality of the sleep regulating network, sleep-disordered breathing is another possible cause of hypersomnia in patients afflicted with the present localization of the lesion.

[Central respiratory failure occurred in the subacute phase of unilateral Wallenberg's syndrome: a case report]

A 46-year-old man developed central respiratory failure in the subacute phase of unilateral lateral medullary infarction. He complained of sudden headache and nausea at first. Neurological examination revealed Wallenberg's syndrome. Acute right lateral medullary infarction caused by the dissecting right vertebral artery was identified by magnetic resonance images. He was transferred to our hospital on the 3rd day after the onset. He was alert and conscious on admission, and became restless gradually later. He was intubated for sudden respiratory failure on the 9th day. Blood gas analysis showed hypercapnia and hypoxia. Central respiratory failure was indicated by the fact that various examinations showed no change of his infarction, no subarachnoid hemorrhage, or no worsening of pneumonia. Ventilatory support was required for a month because of repetitive CO2 narcosis. He was weaned from the ventilator on the 39th day. Only a few reports are available on central respiratory failure associated with the subacute phase of unilateral medullary infarction. Delayed central respiratory failure may be lethal. Careful observation is required on the subacute phase of Wallenberg's syndrome.

Sudden death after medullary infarction - a case report

Sudden death in a stable medullary infarction case frequently induces legal problems. Currently, the etiology of the most reported cases are not known because autopsy is rare. Here, we report one female patient with medullary infarction who experienced a sudden cardiopulmonary arrest during a brain magnetic resonance imaging (MRI) study. The blood flow changes on the MRI indicated that her death resulted from the sudden collapse of systemic circulation. Dysautonomia, or sudden respiratory arrest resulting from brainstem dysfunction, was suspected. In this report, we present her cranial MRI findings and discuss the possible pathophysiology after reviewing the relevant literature. We also recommend certain tests for patients with medullary infarction to prevent the risk of sudden unexpected deaths.

Sudden unexpected death related to medullary brain lesions. Am J Forensic Med Pathol. 2008;29:371-374. [PMID: 19259030 DOI: 10.1097/paf.0b013e3181847dfc]

The sudden unexpected death of a person believed healthy has occasionally been followed by a detailed postmortem examination that revealed no cause of death except for the unexpected presence of a medullary brain lesion. Our review of all available cases of sudden unexpected death related to medullary brain lesions (SUD-MBL) revealed the absence of any specific constellation of ante-mortem disease characteristics, together with the finding that major motor and sensory pathways were grossly preserved in most cases. The wide variety in ages of the victims, and in specific types of tissue pathology affecting the medulla, makes this illness extremely difficult to anticipate when the medullary lesions are not otherwise known to exist during life. SUD-MBL may be a specific clinico-neuropathologic disease entity, having significant importance for forensic investigators trying to establish the cause of sudden unexpected death in a victim of any age. Because victims often harbor their medullary lesions for days or weeks before SUD-MBL, clinical physicians as well need to consider the possibility of medullary brain involvement by any disease process, neurologic or systemic, while managing their patients.

Central alveolar hypoventilation syndrome due to surgical resection for bulbar hemangioblastoma

A 29-year-old man with a history of resected bulbar hemangioblastoma was admitted to hospital with nighttime breathing disturbance, but with apparently normal breathing while awake. After diagnostic work-up, including polysomnographic testing, he was diagnosed as having central alveolar hypoventilation syndrome due to surgical resection for bulbar hemangioblastoma. Non-invasive positive pressure ventilation (NIPPV) via oronasal facemask was given for nocturnal ventilatory support. Two months after leaving our hospital, he was readmitted because of aspiration pneumonia. The pneumonia was successfully treated with antibiotics, but the desaturation during sleep worsened despite non-invasive ventilatory support. Higher bi-level positive pressure using a full facemask successfully alleviated sleep hypoventilation and apnea. To the best of our knowledge, this is the first case report of central alveolar hypoventilation syndrome due to surgical resection for bulbar hemangioblastoma.

Orthostatic hypotension associated with dorsal medullary cavernous angioma

BACKGROUND

Orthostatic hypotension (OH) is a rare manifestation of medulla oblongata lesions that may be because of interruption of descending sympathoexcitatory axons.

AIMS

To illustrate the location of a medullary lesion that produced OH following resection in relationship to the location of putative sympathoexcitatory pathways.

METHOD

A case with dorsal medullary cavernous angioma presenting with OH is described. The possible localization of lesion was compared with distribution of tyrosine hydroxylase (TH)-immunoreactive axons in a comparable section of the medulla of a control brain.

RESULTS

The patient had marked OH after partial removal of the cavernous angioma. Biopsy confirmed the diagnosis. The magnetic resonance imaging location of the lesion overlapped that of TH-immunoreactive axons of the medullary transtegmental tract.

CONCLUSIONS

A restricted lesion of medullary lesion interrupting the catecholaminergic transtegmental tract arising from the sympathoexcitatory C1 neurons of the rostral ventrolateral medulla could result in severe OH.

Repeated hypotensive episodes with fluctuating symptoms in a patient with acute pontomedullary infarction

Dysfunction of cardiovascular regulation, including arterial hypotension, is a rare complication of acute ischemic stroke. We report a patient with an acute pontomedullary infarction who frequently had severe hypotensive episodes. A 78-year-old diabetic man suddenly developed faintness and left hemiparesis. MRI revealed a fresh infarct at the right pontomedullary region, including (or adjacent to) the rostral ventrolateral medulla. During the initial few weeks, urination and head-up tilts frequently induced hypotensive episodes accompanied by systolic blood pressure drops of up to 60 mmHg that were accompanied by fluctuating symptoms. In conclusion, pontomedullary stroke should be considered as a possible cause of hypotension accompanied by fluctuation of neurological symptoms during acute stroke.

Central hypoventilation as the presenting symptom in Hu associated paraneoplastic encephalomyelitis

Central hypoventilation is usually caused by ischaemic or neoplastic lesions of the medulla and upper cervical spinal cord. An autoimmune disorder is not usually considered in the differential diagnosis of this syndrome. We retrospectively identified 14 patients from our database of 202 patients with Hu antibodies who presented with brainstem symptoms. Three were admitted to hospital because of central hypoventilation. All underwent intubation and mechanical ventilation. They could breathe properly while they were awake but suffered deep apnoeas during sleep. Two died, but one is still alive requiring ventilatory assistance during sleep. Autopsy was performed in one of the patients which showed severe inflammatory infiltrates and neuronal loss in the medulla. All patients had normal brain imaging studies and the cause of central hypoventilation was an unsolved problem until Hu antibodies were determined.

Brainstem respiratory control: substrates of respiratory failure of multiple system atrophy

Multiple system atrophy may manifest with severe respiratory disorders, including sleep apnea and laryngeal stridor, which reflect a failure of automatic control of respiration. This function depends on a pontomedullary network of interconnected neurons located in the parabrachial/Kölliker Fuse nucleus in the pons, nucleus of the solitary tract, and ventrolateral medulla. Neurons in the preBötzinger complex expressing neurokinin-1 receptors are critically involved in respiratory rhythmogenesis, whereas serotonergic neurons in the medullary raphe and glutamatergic neurons located close to the ventral medullary surface are involved in central chemosensitivity to hypercapnia, hypoxia, or both. Pathological studies using selective neurochemical markers indicate that these neuronal groups are affected in multiple system atrophy. This finding may provide potential anatomical substrates for the respiratory manifestations of the disease.