Clinical neurophysiology provides functional evaluation of the nervous system by recording electrical activity of the central and peripheral nervous system, requiring a good collaboration between the intensive care and clinical neurophysiology (technicians and consultants). The main electrophysiological tests used in critical care are electroencephalogram (EEG), evoked potential (EP) studies, and electroneuromyography and nerve conduction study (EMG/NCS). Their use is generally an adjunct to clinical examination for diagnostic purposes, outcome prediction, and as functional monitors. The use of neurophysiological tests in neuro-intensive care may especially have an added clinical value in a population of patients that are generally sedated or with decreased level of consciousness impending clinical-neurological assessments.

When dealing with neurological disorders, clinical examination is still paramount but many critical care patients will be sedated and/or paralyzed, rendering clinical assessment impossible. To help assessing sedated neuro critical care patients, neuro-imaging is crucial, as they are both diagnostic and prognostic tools. 

The Most common neuro-imaging techniques are computed tomography, magnetic resonance imaging and optic nerve sheath measurement. Computed tomography (CT) is used in acute settings to detect intracranial bleeding, hydrocephalus or cerebral oedema. Magnetic resonance imaging (MRI) has increased anatomical resolution that could help clinicians detecting small zones of infarction or haemorrhage and evaluating the integrity of white matter. Optic nerve sheath measurement has been used as a non-invasive marker of increased intracranial pressure, which can be measured on CT, MRI or by ultrasound.  

It is impossible to care for the brain without caring for the rest of the body. Aggressive treatments, indicated in most severe cases, carry injurious complications to the brain and other organs, as decompressive craniectomy and barbiturates for example. High quality intensive care is needed to complement complex interventions, to mitigate iatrogenic complications and to prevent avoidable morbidity.

The Glasgow Coma Scale (GCS), a clinical scoring system designed to assess coma, impaired consciousness, and motor responses, is one of the most commonly used to communicate severity of injury (it should be scored after basic resuscitation). Patients with GCS scores of 3 to 8 are classified as severe TBI, those with scores of 9 to 12 are classified as moderate TBI, and those with scores of 13 to 15 are classified as mild TBI. Patients with severe TBI require intensive care admission either to a surgical-trauma ICU or a neuro-ICU depending on associated injuries and/or local hospital organisation and resources. Patients with moderate injury may also require close monitoring and an ICU setting for a decline in neurological status and/or airway compromise and/or to monitor ICP if there is a risk of evolution of a mass lesion. 

Mortality and morbidity after a head injury are influenced by both primary and secondary damage. While there is no effective treatment for primary brain damage, prevention and/or effective treatment of secondary insults to the brain are the key issues in treatment.  

Having ascertained the severity of brain injury at the earliest possible opportunity, this is the best guide to the extent of primary brain injury which has resulted from the direct mechanical trauma at the scene of the accident. We have discussed how this may be achieved clinically using the Glasgow Coma Scale and we shall examine additional methods later in this Task. Changes in these parameters with time may assist you in detecting secondary brain injury, determining the effects of treatment and predicting outcome.  

Traumatic brain injury (TBI) is one of the leading causes of mortality and disability worldwide and has enormous implications not only economically, but also for patients,  families and society. The global incidence of TBI is rising, largely secondary to an increase in road traffic accidents and trauma related violence in low and middle income countries (LMICs). In high income countries (HICs) the demographics are changing with a reduction in traffic-related incidents and an increase in the incidence of falls, particularly in the over 65 years age group. Relevant yearly statistics include:

• For the European Union it has been estimated that at least 2.5 million new cases of TBI occur each year. 

• The standardised Eurostat data estimated that there were 1.5 million TBI-related hospital discharges and 57000 TBI related deaths in 2012 in the 28 member states of the EU. 

• In the Eurostat data the pooled age-adjusted incidence of TBI (hospital discharges) was 287·2 per 100000 people per year, with enormous differences between countries. These are likely to reflect differences in study methods rather than true variation. 

• The median age of patients in HICs has nearly doubled since the 1980s. 

• The male/female ratio is over 2:11  

Intensive care for patients with head injuries is a dynamic process starting at the scene of the accident. During the early stages of hospital care, the patient may require to be managed in a variety of locations including the emergency department (ED), the operating room (OR), the radiology department or the intensive care unit (ICU). It is in the best interests of patient’s care that the intensive care practitioner is thoroughly conversant with the practice of prehospital and immediate emergency care. They should also be aware of the longer-term outcomes and management of patients after TBI; not only to be aware of and prevent the sequelae of secondary injury, as well as avoidable long-term complications, but also to better facilitate the transition of care from the ICU to the ward and/or rehabilitation service.  

While the vast majority of patients (70 to 90%) with a TBI may be classified as mild, this module concentrates on the management of severe TBI. It is important to be aware of the possibility of a mild TBI, particularly when treating patients with polytrauma and/or spinal injuries in the ICU. 

Weakness may precipitate Intensive Care Unit (ICU) admission, and can result from generalised disease states (such as malnutrition), critical illness (such as severe sepsis) or those specific states which primarily affect the neuromuscular system e.g. myasthenia gravis, Guillain–Barré Syndrome (GBS).

Weakness may result from impacts on upper or lower motor neurones (in isolation or with involvement of other peripheral or central nervous system elements), motor end plates (neuromuscular transmission), or skeletal muscle itself. Whatever the cause, ICU admission related to such conditions generally results from respiratory muscle weakness and/or difficulty in swallowing, with consequent aspiration. Early recognition and intervention is crucial: death can result from ventilatory failure and/or aspiration pneumonia, and the autonomic instability which complicates some conditions.

Weakness as a result of neuromuscular conditions can also complicate critical illness, increasing the duration of mechanical ventilation and ICU and hospital stay, and causing post-discharge morbidity and mortality.

You will find the following references helpful in understanding the broad range of neuromuscular conditions encountered in the ICU.

Coma is a state of acute and complete loss of consciousness induced by severe brain injury. Recently, a growing body of literature has enabled a better description of the pathophysiology of this state: new promising theoretical frameworks have been proposed to explain human conscious emergence and maintain, and innovative approaches has been developed to improve diagnosis and early prognostication in this clinically challenging setting ((Greer, Rosenthal and Wu 2014; Rossetti, Rabinstein and Oddo 2016; Menon and Maas 2015) ). It is worth noting that the whole of acquired pathological consciousness perturbation states, currently known as “disorders of consciousness” (DOC), constitutes a behavioural continuum, spanning from acute (e.g. coma) to chronic neurological syndromes (e.g. minimally conscious state, vegetative state). 

A structured, logical, and effective approach to manage these severely brain injured patients is required to:

• organize the support of vital function throughout the period of altered consciousness
  
• permit an early and efficiently treatment of primary brain injuries,
  
• prevent, detect and treat, secondary brain insults.
  

Careful clinical examination and patient’s medical history analysis are the cornerstones of DOC patient management. For example, during coma, determining whether the patient presents a focal sign or not play a crucial role during the stratification of the etiological work-up. Nevertheless, a thorough neurological examination may be difficult to perform in poorly cooperative DOC patients.