Definition

Brainstem lesions are disruptions in the brainstem tissue, including vascular disorders, tumors, or inflammation. The most common vascular disorder is a stroke. Glioma is a prevalent tumor found in the brainstem. Inflammation affecting the brainstem can manifest as encephalitis or multiple sclerosis.

The brainstem is the part of the brain that connects with the spinal cord, serving as a bidirectional information conduit between the brain, spinal cord, and peripheral nerves. It comprises the medulla oblongata, midbrain, and pons. Most cranial nerves, which originate from the brain, exit the brainstem.

The brainstem regulates eye movement, facial sensation, facial expressions, and essential survival functions such as breathing, swallowing, heart rate, blood pressure, and consciousness.

Causes

The most common cause of brainstem lesions is a stroke, which occurs when the blood supply to the brainstem is disrupted. Human life depends on the brainstem's functions for survival, making brainstem strokes particularly dangerous, potentially disrupting critical bodily functions and being life-threatening.

In ischemic strokes (blockages), brain cells lack oxygen due to interrupted blood flow, often caused by blood clots or cholesterol. Clots formed elsewhere can travel to the brain's blood vessels. Hemorrhagic strokes (bleeding) result from ruptured blood vessels, with escaping blood increasing pressure within the brain.

Gliomas, tumors of the brainstem's nerve tissue, are another cause of brainstem lesions. About 60% of cases occur in the pons, with the rest in the midbrain or medulla, potentially growing outside the brainstem. Gliomas account for around 20% of all primary brain tumors in children but less than 2% of all gliomas in adults.

Encephalitis, another cause, involves inflammation of brainstem cells, typically due to infection or autoimmune processes. This inflammation can usually be resolved with proper therapy. Fever in patients with immune disorders should always be suspected as an infection.

Bickerstaff brainstem encephalitis (BBE) is a rare autoimmune disease affecting the nervous system, including the brainstem. BBE's typical symptoms include ataxia (coordination problems), encephalopathy (brain function/structure changes), and ophthalmoplegia (eye muscle paralysis). Common infections associated with BBE are Campylobacter jejuni and Haemophilus influenza, with some cases reported post-COVID-19 infection.

Multiple sclerosis, an autoimmune disease, primarily affects the brainstem's white matter, composed of thickly myelinated nerves. Myelin, a fatty nerve sheath, speeds up nerve signal transmission. Damaged nerves lose their myelin sheath, slowing or stopping function.

Risk factor

Risk factors for brainstem lesions from strokes include:

• Family history of stroke or transient ischemic attack (mini-stroke)
• Age over 65
• Male gender
• African-American, Hispanic, Asian, or Pacific Islander descent
• High blood pressure
• High cholesterol
• Diabetes
• Cardiovascular disease
• Certain blood disorders
• Cancer
• Autoimmune diseases
• Smoking
• Alcohol and drug abuse
• Women over 35, especially smokers
• Hormonal contraceptive use

Brainstem tumor risk factors vary by age, gender, ethnicity, and country, with reports indicating higher incidence in males and those under 20 years of age.

Symptoms

A brainstem stroke can impair vital functions like breathing, heartbeat, eye movement, swallowing, speaking, and hearing. It can also cause vertigo, numbness on one or both sides of the body, or paralysis in the arms or legs.

Multiple sclerosis in the brainstem can cause motor and sensory disruptions, similar to those in the spinal cord or other brain areas, affecting nerve pathways connecting to other brain regions. Symptoms include:

• Movement strength or control issues
• Slurred speech
• Reduced touch, pain, temperature, and vibration sensation
• Balance problems
• Sleep difficulties

Brainstem involvement in multiple sclerosis can uniquely affect cranial nerve functions, such as:

• Double vision
• Hearing problems
• Taste impairment
• Facial muscle weakness
• Swallowing difficulties, including choking or coughing
• Facial pain or sensory disturbances
• Vertigo
• Rarely, blood pressure, heart rate, or breathing issues

BBE symptoms typically follow upper respiratory or gastrointestinal infections, with ophthalmoplegia and ataxia within four weeks, often accompanied by consciousness changes. These symptoms usually resolve spontaneously within 12 weeks.

Encephalitis often presents as altered consciousness (20% of cases), ranging from mild drowsiness to coma.

Diagnosis

For brainstem strokes, radiological exams like MRI, CT scans, Doppler ultrasound, or angiograms follow health history and physical assessments. Heart function tests, including electrocardiograms and echocardiograms, are also conducted. Additional diagnostics like blood tests and kidney and liver function tests may aid diagnosis.

Glioma diagnosis involves:

• Head MRI, is more accurate than CT scans, though CT is useful if MRI is unavailable.
• Cerebrospinal fluid (CSF) analysis.
• Arteriography to distinguish vascular abnormalities from gliomas.

BBE diagnosis is mainly clinical, supported by lab tests and imaging. The definitive test is anti-GQlb antibody analysis in blood, combined with matching symptoms. However, negative antibody tests do not rule out the diagnosis.

Abnormal EEG findings occur in 57% of BBE patients. CSF analysis shows elevated protein levels with normal cell counts in about 25% of patients.

Due to the similarity of brainstem multiple sclerosis symptoms to other disorders, diagnostic tests help pinpoint the lesion. Brain and spinal MRI scans detect demyelinated nerve areas and other abnormalities.

Management

For ischemic strokes, the first treatment step is to remove blood clots. Rapid diagnosis allows for clot-dissolving medication. If feasible, thrombectomy (clot removal using a catheter) is performed. In some cases, stents are placed to widen and keep arteries open.

For hemorrhagic strokes, bleeding must be stopped. A fine wire coil can be placed in the ruptured vessel to halt bleeding. Blood-clot-reducing medication is also necessary. Medical teams ensure heart and lung function during stroke treatment.

Stroke management requires long-term medication and therapy. Physical therapy helps patients regain motor skills, occupational therapy aids daily tasks, and speech therapy improves speaking and swallowing abilities. Some brainstem stroke survivors experience severe disabilities, where psychological counselling assists in adjustment.

Medications for multiple sclerosis can prevent relapses and long-term nerve damage. Therapy and rehabilitation help optimize strength and coordination while swallowing therapy eases eating and drinking.

Healthcare providers or therapists might recommend corrective lenses or eye patches for double vision and hearing aids for hearing issues.

Encephalitis responds well to immunotherapy, reducing recurrence risk and offering good long-term prospects. Glioma treatment involves radiotherapy and/or chemotherapy.

Complications

Brainstem strokes can lead to loss of smell and taste, with rare complications like coma and locked-in syndrome, where the entire body is paralyzed except for eye muscles. Patients in this syndrome can think and communicate through eye movements.

Glioma-induced brainstem compression can impair affected nerve functions, with sudden death possible due to increased brain pressure. Some glioma types have a poor prognosis, with survival around 10 months, and only 10% living beyond two years post-diagnosis. However, average adult survival is 30-40 months.

Prevention

Approximately 80% of strokes are preventable. Preventive measures include:

• Low-fat, low-salt diet
• Eating healthy foods like fruits, vegetables, and fish
• Regular exercise 3-5 times a week for 15-30 minutes
• Avoiding smoking
• Avoiding alcohol or drug abuse
• Monitoring blood fat levels
• Controlling blood pressure with medication and lifestyle changes
• Managing other health issues like obesity, hypertension, diabetes, or high cholesterol with medical consultation

When to see a doctor?

Brainstem lesions are serious health issues that can progress rapidly. If you experience any of the above brainstem disease symptoms or have the mentioned risk factors, see a doctor promptly to prevent the disease from worsening.

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