Figure 1: Five components of PHES testing
Number connection test – A: Instruct the patient to join numbered circles in order and record time taken. Tests psychomotor function.
inhospitable environment for urease-producing bacteria, thus reducing luminal ammonia synthesis and absorption. However, approximately 5% of patients suffer side effects so severe, they discontinue treatment. Antibiotics Antibiotics with activity against urease-producing bacteria have proven value in treating HE, as they reduce ammonia production. Rifaximin is a non-absorbable antibiotic with broad-spectrum activity against both aerobic and anaerobic gram positive and gram-negative bacteria. Since gaining approval from the FDA in March 2010, it has largely overtaken the use of neomycin and vancomycin in the USA, which have been associated with adverse effects such as ototoxicity and nephrotoxicity. Other pharmacological interventions include L-ornithine aspartate and
Number connection test – B Instruct the patient to join numbered circles and alphabets in order and record time taken. Tests attention and executive functioning.
sodium benzoate, which aim to increase metabolism of ammonia by providing alternative detoxification pathways. The benzodiazepine receptor antagonist flumazenil has been used previously, but concerns have been raised over its potential to decrease the threshold for seizures and is not recommended.
Serial dotting test Instruct the patient to dot the centre of circles. Tests processing speed.
Nutritional therapies Vegetable-based protein Contrary to previous reports, patients with HE should not be protein restricted. They are often in a catabolic state and require 1-1.5g/kg of protein per day. Vegetable protein tends to be better tolerated than meat protein. In addition, vegetable proteins increase intestinal transit time and colonic motility due to their high fibre content, as well as improving faecal nitrogen output. However, the clinical utility of a vegetable protein based diet is limited by poor patient compliance and is not used routinely in the UK. Branched chain amino acids The administration of preparations high in BCAAs and low in AAAs is based on reducing transmission of AAAs across the BBB, thus reducing the production of false neurotransmitters, which can contribute to encephalopathy. Although studies are not conclusive, BCAAs can improve both recovery and duration of hospital admissions. However, they are expensive and are not readily available.
Line tracing test Instruct the patient to trace a path from beginning to end, without touching the borders Tests processing speed.
Orthotopic liver transplant HE is usually indicative of decompensating chronic liver disease and ultimately the best treatment is an OLT. However, this is not always possible as patients are usually too sick to survive an operation by this stage. It is therefore important to consider patients’ eligibility for transplant as soon as possible following an acute episode and particularly if HE grade is rising quickly in ALF as this is a poor prognostic sign and requires urgent discussion with a liver transplant centre.
Long-term management Following an episode of HE it is usual for patients to remain on empiric therapy (lactulose) for an indefinite period of time, although adverse effects due to lactulose may affect adherence, or until they receive an OLT. The aim of maintenance therapy is to prevent further episodes of HE and to allow patients to continue with daily functioning.
Digital symbol test Patient is instructed to familiarise the symbols matched with each number. The patient is then timed while filling in the corresponding symbol to the digit. Tests attention and processing speed.
CONCLUSION HE is a neuropsychiatric syndrome, whose symptoms exist on a continuum. Early recognition and management is imperative in optimising outcome.
REFERENCES References available on request (
magazine@informa.com)
MORE INFO The London Clinic is the UK’s largest independent, not-for-profit, hospital. Please visit:
www.thelondonclinic.co.uk for more information.
056 ARAB HEALTH MAGAZINE ISSUE 2 2012
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