Causes of unconsciousness

Introduction

There are numerous causes of unconsciousness and most of them are associated in some way with an underlying medical condition that usually causes other problems as well.

Among the most common causes of unconsciousness are various types of head injuries such as cerebral compression, concussion or skull fracture. Cerebral compression is a condition in which an increased amount of pressure inside the skull causes a disruption of brain’s functions. It usually gets caused by blood clotting which results from significant blows to the head. The condition can be easily recognized by irregular breathing, weakness, flushed face and an altered conscious state.

The patient must seek immediate medical attention. Concussion is a brain injury characterized by dizziness, vomiting, headache, temporary memory loss and a lack of coordination. A person who suffered a concussion needs to seek immediate medical attention. Skull fracture is a condition in which a person suffers a break in the continuity of the skull bone.

The condition can be characterized by black eyes, altered conscious state, unequal pupils and lacerations and the patients that have suffered a skull fracture also need immediate medical attention. Diabetes is a condition in which the pancreas cannot produce any insulin and it can also be the cause of unconsciousness in certain cases.

The patient may experience confusion, dizziness, faster breathing, an altered conscious state and drowsiness. He/she needs to ingest sugar immediately and if the condition gets worse than medical attention is required.

Another condition that may be the cause of unconsciousness is stroke. A person experiences a narrowed, blocked or ruptured artery which takes blood to the brain so the cerebral functions become affected. Stroke can be caused by head injury, blood clots, high blood pressure or a tumor.

The condition can be instantly recognized by abnormal behavior, slurred speech, disturbed vision, dizziness, confusion, and headaches. Unconscious patients need to be transported to the hospital immediately, while those who remain conscious need to be positioned comfortably and closely monitored until the ambulance arrives. Seizure is a condition characterized by disrupted electrical activity in the brain and it can be triggered by poisoning, fever, different diseases, injuries and infections.

A person can experience strange sensations prior to a seizure. Once the seizure occurs it should not be stopped and the person who has experienced it requires immediate medical attention. Fainting is a condition characterized by a loss of consciousness caused by reduction of the blood flow to the brain due to pain, emotional shock, lack of food or other disturbances.

Medical attention must be sought in order to determine the cause of fainting.

Unconsciousness and Covid-19

In patients with coronavirus disease 2019 (COVID-19) who are admitted to the intensive care unit (ICU) for respiratory distress, an encephalopathy, most notably in the form of delirium, occurs in up to 84%. Brain MRI studies in patients in the ICU with COVID-19, including those with prolonged comatose state, reported varying degrees of MRI abnormalities, although few to no details were reported on the clinical picture, course, and prognosis of prolonged unconsciousness in such patients. Here, we report a case series of patients with COVID-19 admitted to the ICU for respiratory failure who, after cessation of sedatives, remained unconscious for longer than expected periods.

The brain imaging abnormalities found in our described case and other patients within our series are in line with recently reported series of brain imaging in patients with COVID-19 and a postmortem neuropathologic analysis, showing microbleeds and white matter abnormalities in varying degrees. Some of these abnormalities have also been reported previously in other critical illnesses, including a prolonged reversible comatose state in a case of sepsis.
The main differential diagnosis in our case was a persistent comatose state due to parainfectious autoimmune-mediated encephalitis or critical illness–related encephalopathy. The clinical course in our case series, normal CSF analyses, and spontaneous improvement without any corticosteroids most likely support a critical illness–related encephalopathy, although a clear distinction is difficult to make. A long ICU course in severe COVID-19 is not unusual. Due to the use of sedatives and muscle relaxants during longer periods in patients with COVID-19 admitted to the ICU, such patients often develop a severe form of ICU-acquired weakness. Factors such a long use of sedatives and the presence of severe generalized muscle weakness (present in all our cases) complicate assessment of the level of consciousness.
In all of our patients, a similar clinical pattern was observed during recovery of their unconsciousness. Opening of the eyes occurred in the first week after sedatives were stopped in 5 of the 6 patients without any other motor reactions with generalized flaccid paralysis. This was followed by visual tracking of people within 2 weeks after cessation of sedatives. Obeying commands (mostly through facial musculature) occurred between 8 and 31 days after cessation of sedatives.
Our findings corroborate a recent case report showing intact functional connectivity in the default mode network using fMRI in a patient with prolonged unconsciousness admitted to the ICU for respiratory failure due to COVID-19. One of the main drawbacks of our study is the selection bias that is inherent to case series. Although the patients recovered from their prolonged unconscious state, it is likely that long-term cognitive or physical deficits remain present, in line with many reports on long-term outcomes in patients with COVID-19.

Neurologists are frequently consulted due to neurologic symptomatology in patients with COVID-19. As our case series shows, it is conceivable that neurologists could be faced with the dilemma to prognosticate on the basis of a prolonged state of unconsciousness, all with the background of a pandemic with the need for ICU capacity exceeding available resources. It is important to take into account the possible reversibility of prolonged unconsciousness in patients with COVID-19 admitted to the ICU, which warrants watchful waiting in such cases.

✓ Fact confirmed: Prolonged Unconsciousness Following Severe COVID-19 Wilson F. Abdo, Catharina I. Broerse, Bart P. Grady, Agnes A.A.C.M. Wertenbroek, Onno Vijlbrief, Marc P. Buise, Menno Beukema, Mark van der Kuil, Anil M. Tuladhar, Frederick J.A. Meijer, Johannes G. van der Hoeven; March 09, 2021