Hemiparesis

Whereas hemiparesis refers to muscular weakness of one half (left or right) of the body, hemiplegia refers to partial or complete paralysis. Both these conditions are related and part of the continuum of nerve dysfunction and muscular weakness. Hemiplegia is considered to be further down the spectrum from hemiparesis. However, hemiplegia should not be confused with paraplegia, the paralysis of the lower half of the body. Hemiplegia paralysis can change over time and some mobility and function can be regained, at times spontaneously, but mostly with timely rehabilitation physiotherapy.

(Read more: Spinal cord injury)

One-sided weakness arises in arms, hands, face, chest, legs or feet in the affected half of the body (left or right side). This weakness and loss of motor control can lead to the following problems:

• Loss of balance
• Difficulty walking
• Increased risk of slipping or falling
• Impaired ability to grab or grasp objects
• A decrease in movement precision
• Muscle fatigue
• Lack of coordination
• Numbness and tingling sensation in the affected side of the body
• Occasional lack of sensation in the affected side of the body
• Slurred speech

Other accompanying sensory features can be related to disturbances of:

• Sight
• Taste
• Smell
• Touch
• Hearing

While stroke remains the most common cause of hemiparesis, some other conditions affecting the central nervous system (brain and spinal cord) can also be responsible. Some common causes of hemiparesis and hemiplegia are:

• Vascular: Causes that impair the blood and oxygen flow in key arteries supplying crucial areas of the central nervous system can lead to muscle weakness or paralysis. Examples are: 
  • Cerebral haemorrhage 
  • Stroke: Ischaemic (thrombotic or embolic), haemorrhagic, transient ischaemic attacks (TIAs)
  • Cerebral palsy
• Infective: Infection of the central nervous system tissue can impair its functioning. Common causes are:
  • Encephalitis 
  • Meningitis
  • Brain abscess
  • Cerebral palsy
  • Spinal epidural abscess (Read more: Brain infection)
• Neoplastic (related to cancer or tumours): Tumorous mass impinging on the brain or spinal cord can alter its motor functioning. 
  • Glioma
  • Meningioma
  • Brain tumours
  • Spinal cord tumours
• Demyelination: The protective myelin sheath covering of nerves is lost and nerve dysfunction sets in. Causes can be: 
  • Multiple sclerosis
  • Disseminated sclerosis
  • ADEM
  • Neuromyelitis optica
• Traumatic: Injury to central nervous tissue (brain or spinal cord) will impact motor activity. 
  • Cerebral lacerations
  • Subdural hematoma
  • Epidural hematoma
  • Cerebral palsy
  • Vertebral compression fracture (Read more: Spine fracture)
• Iatrogenic (caused by medical intervention or error): An example can be when injections, like local anaesthetics, intended to desensitise nerve endings and produce a pain-free medium for the doctor to work in, can accidentally be given into arteries. This can cause sclerosis (or thickening) of the arteries, impairing blood flow. This is, however, a very rare occurrence. 
• Post-ictal: The phase after a person recovers from a seizure is called the post-ictal phase. It is marked by increased sleepiness and confusion and can be associated with inability to move.
• Congenital: Where the underlying cause of weakness or paralysis is present since birth. Examples are:
  • Cerebral palsy
  • Neonatal-Onset Multisystem Inflammatory Disease (NOMID)
• Degenerative: With age, the tissue forming the nervous system begins to break down. However, some diseases can accelerate the process and can cause damage prematurely or unnaturally. Such diseases can be: 
  • ALS (amyotrophic lateral sclerosis)
  • Corticobasal degeneration
• Parasomnia: In some people, the central nervous system behaves unusually during sleep; this state is referred to as parasomnia. Sleep paralysis is one such problem plaguing individuals.

The diagnosis is usually a clinical one, meaning it is based on obvious clinical features experienced and displayed by the patient. However, laboratory investigations and radiological imaging help elucidate the underlying cause and measure the progress of recovery.

History: The doctor begins by taking a thorough medical history of the patient. In case the patient is unable to answer, a close attendant of the patient who witnessed the event can help. Keen attention is paid to the events that lead up to the sudden onset of muscular weakness and symptoms. A past history of lifestyle diseases (like diabetes mellitus, raised cholesterol and hypertension), medications and previous heart attacks is taken. A family history of similar diseases is noted. The patient’s psychological state (increased mental stress, depression or anxiety) and habits like smoking or other unhealthy lifestyle choices are also recorded.

(Read more: How to quit smoking)

Examination: Following a medical history, a thorough physical examination is conducted. Blood pressure readings are noted and a special emphasis is laid on neurological and cardiovascular examination. Not only does neurological examination help establish a baseline of neurological and motor deficits, it also helps monitor the patient’s recovery. Cardiovascular examination may show signs of underlying heart disease that could have triggered the stroke.

Although hemiparesis is diagnosed and monitored clinically, laboratory investigations and radiological imaging help understand the cause of the incident leading up to it.

Investigations required to diagnose hemiparesis include:

• Blood tests:
  • Complete blood count: Altered white blood cell count can point to infectious causes. 
  • Blood smear microscopy: Sickle cell anaemia, an unusual cause of stroke, can be detected.
  • Blood glucose levels: Diabetes mellitus can be assessed.
  • Blood lipid panel: Blood cholesterol levels are assessed.
  • Coagulation profile: In strokes occurring in the young, abnormal blood clotting is often responsible.
  • Immunological tests: Antibodies producing autoimmune vasculitis can be detected.
• Radiological imaging tests:
  • Brain and spinal cord imaging: Both MRI and CT scans are useful modalities that detect the lesions or haemorrhages responsible for the clinical features. They can also detect tumours and other masses.

Medical management: If the underlying cause of hemiparesis is a disease other than stroke, it needs definitive medical therapy. Infections would require antibiotics or antivirals. Autoimmune conditions like multiple sclerosis or vasculitis need immunotherapy and, sometimes, intravenous corticosteroids. Management of hemiparesis requires a comprehensive approach.

Conservative management: The earlier rehabilitation therapy is started, the better the outcome.

• Modified constraint-induced movement therapy (mCIMT): The stronger, or unaffected, side of the body is restrained and, under the supervision of the medical team, patients are encouraged to use the weakened side (left or right).
• Electrical stimulation: Small pads are placed on the impaired half of the body muscle and small electrical charges are given through this device that can potentially activate muscles.
• Cortical stimulation: A small electrode is placed over the dural membrane of the brain while the patient does rehabilitation exercises.
• Mental imagery: The patient is asked to visualise and imagine movement of the impaired half of the body. The areas in the brain that control this visualisation and the actual movement overlap and working this part of the brain can help elicit movement when coupled with other exercises.
• Assistive devices: Braces, canes, walkers, wheelchairs and other orthopaedic devices, on a case by case basis, can help the patient continue to live a meaningful life.
• Lifestyle changes: In order to accept the new limitation of movement, home modifications should be made. Raised toilet seats, anti-slip mats, objects of daily use kept at closer distances, etc. may be useful measures. Assistive devices and occupational therapy help.

Psychological therapy: The new limitations of movement and activities of daily living can put the patient under undue mental duress. Additionally, preexisting stress, anxiety or depression that could have potentially caused the stroke needs to be addressed.

Overall long term outcome of hemiparesis and hemiplegia depends on the severity of lesion, extent of damage and area affected in the central nervous system. Although at times complete recovery to pre-stroke status is not possible, with timely initiation of and adherence to rehabilitation therapy, sufficient muscle strength and movement can be regained to lead a meaningful life. Occupational therapy, or learning new ways to do everyday tasks, might be necessary. While hemiplegia or paralysis can be permanent, some extent of sensation and movement can be regained in a few cases. After suffering from one stroke, the patient should also focus on reducing their risk of experiencing a second one.