Instability

Instability refers to the loss of balance or lack of body control. It manifests as a feeling of insecurity when standing upright, increasing the risk of accidents and falls.

The ability to maintain balance is achieved through the interaction of multiple body systems, including muscles, bones, joints, nerves, the inner ear, eyes, blood vessels, and the heart. A dysfunction in any of these systems can lead to instability, although the most common cause is a failure of the vestibular system (located in the bony labyrinth of the inner ear).

Instability negatively affects patients’ quality of life, even if it does not necessarily represent a serious health risk. Therefore, it is a condition that requires a detailed evaluation in order to establish an accurate diagnosis and implement the most appropriate treatment in each case.

Symptoms

The characteristic symptoms of instability include:

• Loss of balance.
• Lack of stability.
• Vertigo: sensation that the environment is moving or spinning.
• Feeling of floating.
• Dizziness.
• Nausea, cold sweating.
• Presyncope: feeling of lightheadedness and, in some cases, fainting.
• Blurred vision.
• Disorientation.
• Increased tendency to fall.

Causes

Instability can arise from a wide variety of causes:

• Physical causes: structural or sensory alterations:
  • Benign paroxysmal positional vertigo: an inner ear abnormality causes brief episodes of dizziness when the head changes position.
  • Vestibular neuritis: inflammation of the vestibular nerve located in the inner ear as a result of a viral infection.
  • Ménière’s disease: believed to be caused by excess fluid in the inner ear, an autoimmune response, or infection. It presents with tinnitus, ear fullness, fluctuating hearing loss, and a sensation that everything is spinning.
  • Migraines: intense, throbbing headache with sensitivity to sound and light.
  • Acoustic neuroma: benign tumor located in the vestibulocochlear nerve, which connects the inner ear to the brain.
  • Ramsay Hunt syndrome or otic herpes zoster: viral infection of the facial nerve.
  • Concussion: traumatic brain injury caused by a blow or violent head movement that temporarily disrupts brain function.
  • Motion sickness: arises from a conflict between what the eyes see and what the balance center perceives during travel or amusement rides.
  • Cataracts: opacity of the lens (the eye’s natural lens), causing blurred vision and reduced depth perception, leading to instability and imbalance.
  • Macular degeneration: damage to the macula (center of the retina), resulting in loss of sharp central vision. Imbalance may arise from distorted vision.
  • Ocular muscle imbalance: the six muscles responsible for eye movement do not work in coordination.
  • Hyperventilation: abnormally rapid breathing that reduces blood carbon dioxide levels, causing tingling in the hands and dizziness.
  • Brain tumor: presence of a neoplasm in brain areas controlling balance and coordination (cerebellum and frontal lobes), leading to instability.
  • Stroke (cerebrovascular accident): interruption of cerebral blood flow, reducing oxygen supply to brain tissue.
  • Cervical injury: damage to the cervical vertebrae and skull base.
  • Cervical spondylosis: degeneration of the joints and intervertebral discs in the neck.
• Motor causes: coordination or strength disorders:
  • Peripheral neuropathy: damage to nerves in the legs.
  • Muscle weakness.
  • Sarcopenia: loss of muscle mass.
  • Joint instability: ligament injuries (sprains), osteoarthritis, meniscal or patellar injuries.
  • Foot deformities (cavovarus foot, flat foot).
  • Arthritis: inflammation, stiffness, reduced mobility, and joint pain.
  • Fractures of the lower limbs.
  • Parkinson’s disease: progressive neurodegenerative disorder affecting the central nervous system, causing resting tremor and postural instability, among other symptoms.
• Hemodynamic causes: abnormalities in blood flow:
  • Orthostatic hypotension: blood pressure drops upon standing quickly.
  • Cardiac arrhythmias: abnormal heart rhythm, either too fast or too slow.
  • Heart failure: the heart cannot pump enough blood to adequately oxygenate tissues.
  • Blood vessel narrowing.
  • Hypertrophic cardiomyopathy: thickening of the heart muscle.
  • Shock: acute syndrome in which blood and oxygen supply to vital organs is insufficient.
• Psychological causes: psychogenic vertigo or emotional dizziness is linked to mental disorders and has no underlying organic cause:
  • Major depressive disorder: lack of energy may manifest as physical instability.
  • Anxiety and chronic stress: increased cortisol and adrenaline may affect the vestibular system.
  • Panic attacks: intense distress produces symptoms similar to cardiac problems, including dizziness.
• Pharmacological causes: certain medications may induce instability:
  • Antihypertensive drugs.
  • Sedatives.
  • Antidepressants.
  • Diuretics: reduce fluid volume and blood pressure.
  • Antiepileptic drugs.
  • Some antibiotics: may damage the inner ear; these are known as ototoxic antibiotics.

Risk factors

Factors that increase the risk of balance disorders are related to their underlying causes. The most relevant include:

• Age: older adults commonly present muscle loss, reduced visual acuity, and gait disturbances, walking with shorter steps and reduced joint mobility. All these factors may trigger instability.
• Musculoskeletal disorders.
• Neurological diseases.
• Inner ear conditions.
• Cardiovascular disorders.
• Cognitive impairment.
• Mental illness.
• Treatments affecting stability.

Complications

Instability may lead to the following complications:

• Falls.
• Severe injuries: trauma, contusions, fractures.
• Sedentary lifestyle: fear of losing balance leads patients to limit physical activity.
• Anxiety and insecurity when moving.
• Low self-esteem, social isolation.
• Depression.

Which specialist treats instability?

Instability is usually managed within the Neurology specialty, in collaboration with specialists in Otorhinolaryngology and Ophthalmology.