Bulbar syndrome

Bulbar syndrome develops with damage to the caudal sections of the brainstem (medulla oblongata) or its connections with the executive apparatus. The functions of the medulla oblongata are diverse and have vital significance. The nuclei of the IX, X and XII nerves are the control centers of the reflex activity of the pharynx, larynx and tongue and participate in ensuring articulation and swallowing. They receive interoceptive information and are related to many visceral reflexes (coughing, swallowing, sneezing, salivation, sucking) and various secretory reactions. The medial (posterior) longitudinal fasciculus passes through the medulla oblongata, which is important in regulating head and neck movements and coordinating the latter with eye movements. It contains relay nuclei of the auditory and vestibular conductors. Ascending and descending pathways pass through it, connecting the lower and higher levels of the nervous system. The reticular formation plays an important role in facilitating or inhibiting motor activity, regulating muscle tone, conducting afferentation, in postural and other reflex activity, in controlling consciousness, as well as visceral and vegetative functions. In addition, through the vagus system, the medulla oblongata participates in regulating respiratory, cardiovascular, digestive and other metabolic processes in the body.

Here we will consider the expanded forms of bulbar paralysis, developing with bilateral lesions of the nuclei of the IX, X and XII nerves, as well as their roots and nerves inside and outside the skull. Here we also include lesions of the corresponding muscles and synapses, which lead to the same disorders of bulbar motor functions: swallowing, chewing, articulation, phonation and breathing.

[ 1 ], [ 2 ], [ 3 ]

Causes of bulbar syndrome

1. Motor neuron diseases (amyotrophic lateral sclerosis, Fazio-Londe spinal muscular atrophy, Kennedy bulbospinal muscular atrophy).
2. Myopathy (oculopharyngeal, Kearns-Sayre syndrome).
3. Dystrophic myotonia.
4. Paroxysmal myoplegia.
5. Myasthenia gravis.
6. Polyneuropathy (Guillain-Barré, post-vaccination, diphtheria, paraneoplastic, hyperthyroidism, porphyria).
7. Polio.
8. Processes in the brainstem, posterior cranial fossa and craniospinal region (vascular, tumor, syringobulbia, meningitis, encephalitis, granulomatous diseases, bone anomalies).
9. Psychogenic dysphonia and dysphagia.

[ 4 ], [ 5 ]

Motor neuron diseases

The final stage of all forms of amyotrophic lateral syndrome (ALS) or the onset of its bulbar form are typical examples of bulbar dysfunction. The disease usually begins with a bilateral lesion of the nucleus of the 12th nerve and its first manifestations are atrophy, fasciculations, and paralysis of the tongue. In the early stages, dysarthria without dysphagia or dysphagia without dysarthria may occur, but a progressive deterioration of all bulbar functions is observed quite quickly. At the onset of the disease, difficulty swallowing liquid food is observed more often than solid food, but as the disease progresses, dysphagia also develops when eating solid food. In this case, weakness of the chewing and then facial muscles joins the weakness of the tongue, the soft palate hangs down, the tongue in the oral cavity is motionless and atrophic. Fasciculations are visible in it. Anarthria. Constant salivation. Weakness of the respiratory muscles. Symptoms of upper motor neuron involvement are detected in the same area or in other regions of the body.

[ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ]

Diagnostic criteria for amyotrophic lateral sclerosis

• presence of signs of lower motor neuron damage (including EMG - confirmation of the anterior horn process in clinically intact muscles); clinical symptoms of upper motor neuron damage (pyramidal syndrome); progressive course.

“Progressive bulbar palsy” is today considered as one of the variants of the bulbar form of amyotrophic lateral sclerosis (just like “primary lateral sclerosis” as another type of amyotrophic lateral sclerosis, occurring without clinical signs of damage to the anterior horns of the spinal cord).

Progressive bulbar palsy may be a manifestation of progressive spinal amyotrophy, in particular, the terminal stage of Werdnig-Hoffmann amyotrophy, and in children, Fazio-Londe spinal amyotrophy. The latter is an autosomal recessive spinal amyotrophy with onset in early childhood. In adults, X-linked bulbar spinal amyotrophy is known, beginning at the age of 40 years and older (Kennedy disease). Characterized by weakness and atrophy of the muscles of the proximal upper limbs, spontaneous fasciculations, limited range of active movements in the arms, decreased tendon reflexes from the biceps and triceps brachii muscles. As the disease progresses, bulbar (usually mild) disorders develop: choking, tongue atrophy, dysarthria. Leg muscles are involved later. Characteristic features: gynecomastia and pseudohypertrophy of the calf muscles.

In progressive spinal amyotrophies, the process is limited to damage to the cells of the anterior horns of the spinal cord. Unlike amyotrophic lateral sclerosis, the process here is always symmetrical, it is not accompanied by symptoms of upper motor neuron involvement and has a more favorable course.

[ 11 ], [ 12 ], [ 13 ], [ 14 ], [ 15 ]

Myopathies

Some forms of myopathy (oculopharyngeal, Kearns-Sayre syndrome) may manifest as a violation of bulbar functions. Oculopharyngeal myopathy (dystrophy) is a hereditary (autosomal dominant) disease, the peculiarity of which is a late onset (usually after 45 years) and muscle weakness, which is limited to the facial muscles (bilateral ptosis) and bulbar muscles (dysphagia). Ptosis, swallowing disorders and dysphonia slowly progress. The main maladaptive syndrome is dysphagia. The process spreads to the extremities only in some patients and in the late stages of the disease.

One of the forms of mitochondrial encephalomyopathy, namely Kearns-Sayre syndrome ("ophthalmoplegia plus") manifests itself, in addition to ptosis and ophthalmoplegia, by a myopathic symptom complex that develops later than the eye symptoms. Involvement of the bulbar muscles (larynx and pharynx) is usually not severe enough, but can lead to changes in phonation and articulation, choking.

[ 16 ], [ 17 ], [ 18 ], [ 19 ]

Obligatory signs of Kearns-Sayre syndrome:

• external ophthalmoplegia
• pigmentary degeneration of the retina
• cardiac conduction disturbances (bradycardia, atrioventricular block, syncope, possible sudden death)
• increased protein levels in cerebrospinal fluid

[ 20 ], [ 21 ]

Dystrophic myotonia

Dystrophic myotonia (or myotonic dystrophy of Rossolimo-Kurshman-Steinert-Batten) is inherited in an autosomal dominant manner and affects men 3 times more often than women. Its onset occurs at the age of 16-20 years. The clinical picture consists of myotonic, myopathic syndromes and extramuscular disorders (dystrophic changes in the lens, testicles and other endocrine glands, skin, esophagus, heart and sometimes in the brain). Myopathic syndrome is most pronounced in the muscles of the face (chewing and temporal muscles, which leads to a characteristic facial expression), neck and, in some patients, in the limbs. Damage to the bulbar muscles leads to a nasal voice, dysphagia and choking and sometimes to respiratory disorders (including sleep apnea).

[ 22 ], [ 23 ], [ 24 ], [ 25 ], [ 26 ], [ 27 ]

Paroxysmal myoplegia (periodic paralysis)

Paroxysmal myoplegia is a disease (hypokalemic, hyperkalemic and normokalemic forms) manifested by generalized or partial attacks of muscle weakness (without loss of consciousness) in the form of paresis or plegia (up to tetraplegia) with decreased tendon reflexes and muscle hypotonia. The duration of attacks varies from 30 minutes to several days. Provoking factors: abundant carbohydrate-rich food, abuse of table salt, negative emotions, physical activity, night sleep. Only in some attacks is the involvement of the cervical and cranial muscles noted. Rarely, the respiratory muscles are involved to one degree or another.

Differential diagnosis is carried out with secondary forms of myoplegia, which are found in patients with thyrotoxicosis, with primary hyperaldosteronism, hypokalemia in some gastrointestinal diseases, kidney diseases. Iatrogenic variants of periodic paralysis are described when prescribing drugs that promote the removal of potassium from the body (diuretics, laxatives, licorice).

Myasthenia

Bulbar syndrome is one of the dangerous manifestations of myasthenia. Myasthenia gravis is a disease whose leading clinical manifestation is pathological muscle fatigue, which decreases until complete recovery after taking anticholinesterase drugs. The first symptoms are often disorders of the oculomotor muscles (ptosis, diplopia and limited mobility of the eyeballs) and facial muscles, as well as muscles of the extremities. Approximately one third of patients have involvement of the masticatory muscles, muscles of the pharynx, larynx and tongue. There are generalized and local (mainly ocular) forms.

Differential diagnosis of myasthenia is carried out with myasthenic syndromes (Lambert-Eaton syndrome, myasthenic syndrome in polyneuropathies, myasthenia-polymyositis complex, myasthenic syndrome in botulinum intoxication).

[ 28 ], [ 29 ], [ 30 ], [ 31 ]

Polyneuropathies

Bulbar paralysis in polyneuropathies is observed in the picture of generalized polyneuropathic syndrome against the background of tetraparesis or tetraplegia with characteristic sensory disturbances, which facilitates the diagnosis of the nature of bulbar disorders. The latter are characteristic of such forms as acute demyelinating polyneuropathy of Guillain-Barré, post-infectious and post-vaccination polyneuropathies, diphtheria and paraneoplastic polyneuropathy, as well as polyneuropathy in hyperthyroidism and porphyria.

[ 32 ], [ 33 ], [ 34 ], [ 35 ], [ 36 ]

Polio

Acute poliomyelitis, as a cause of bulbar paralysis, is recognized by the presence of general infectious (preparalytic) symptoms, rapid development of paralysis (usually in the first 5 days of the disease) with greater damage to the proximal sections than to the distal ones. A period of reverse development of paralysis soon after its onset is characteristic. Spinal, bulbar and bulbospinal forms are distinguished. The lower limbs are most often affected (in 80% of cases), but the development of hemitype or cross syndromes is possible. Paralysis is flaccid with loss of tendon reflexes and rapid development of atrophy. Bulbar paralysis can be observed in the bulbar form (10-15% of the entire paralytic form of the disease), in which the nuclei of not only the IX, X (less often XII) nerves, but also the facial nerve are affected. Damage to the anterior horns of segments IV-V can cause respiratory paralysis. In adults, the bulbospinal form develops more often. Involvement of the reticular formation of the brainstem can lead to cardiovascular (hypotension, hypertension, cardiac arrhythmia), respiratory ("ataxic breathing") disorders, swallowing disorders, and disturbances in the level of wakefulness.

Differential diagnosis includes other viral infections that can affect the lower motor neuron: rabies and herpes zoster. Other diseases that often require differential diagnosis with acute poliomyelitis include Guillain-Barré syndrome, acute intermittent porphyria, botulism, toxic polyneuropathies, transverse myelitis, and acute spinal cord compression in epidural abscess.

[ 37 ], [ 38 ]

Processes in the brainstem, posterior cranial fossa and craniospinal region

Some diseases sometimes easily involve both halves of the medulla oblongata, given the small size and compact shape of the caudal part of the brainstem: tumors of intramedullary (gliomas or ependymomas) or extramedullary nature (neurofibromas, meningiomas, hemangiomas, metastatic tumors); tuberculoma, sarcoidosis and other granulomatous processes may resemble clinical symptoms of a tumor. Space-occupying processes are sooner or later accompanied by an increase in intracranial pressure. Parenchymatous and subarachnoid hemorrhages, craniocerebral trauma and other processes accompanied by intracranial hypertension and herniation of the medulla oblongata into the foramen magnum may lead to hyperthermia, respiratory disorders, coma and death of the patient from respiratory and cardiac arrest. Other causes: syringobulbia, congenital disorders and anomalies of the craniospinal region (platybasia, Paget's disease), toxic and degenerative processes, meningitis and encephalitis leading to dysfunction of the caudal parts of the brainstem.

[ 39 ], [ 40 ], [ 41 ], [ 42 ], [ 43 ], [ 44 ]

Psychogenic dysphonia and dysphagia

Psychogenic disorders of bulbar functions sometimes require differential diagnosis with true bulbar palsy. Psychogenic disorders of swallowing and phonation can be observed both in the picture of psychotic disorders and within the framework of conversion disorders. In the first case, they are usually observed against the background of clinically obvious behavioral disorders, in the second, they are rarely a monosymptomatic manifestation of the disease and in this case their recognition is facilitated by identifying polysyndromic demonstrative disorders. It is necessary to use both positive criteria for diagnosing psychogenic disorders and excluding organic diseases using modern paraclinical examination methods.

[ 45 ], [ 46 ], [ 47 ], [ 48 ], [ 49 ]

Diagnostic studies for bulbar syndrome

General and biochemical blood test; general urine analysis; CT or MRI of the brain; EMG of the muscles of the tongue, neck and limbs; clinical and EMG tests for myasthenia with pharmacological load; examination by an ophthalmologist; ECG; cerebrospinal fluid analysis; esophagoscopy; consultation with a therapist.

[ 50 ], [ 51 ], [ 52 ], [ 53 ]