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ecologically valid in that they test ‘everyday memory’ skills, such as putting a name to a face
and prospective memory functions (remembering that you have to do something at some
point in the future). Tests are also available to examine retrieval from long-term memory
store, including autobiographical recall and memory for public events.

Most neuropsychological assessments will include a basic screen of expressive and receptive
language skills, as well as perceptual abilities. They will also include some tests designed to
be sensitive to frontal lobe disturbance. All of these areas can be examined in greater detail
with specialist test batteries such as the Multilingual Aphasia Examination, (MAE) the Visual
Object Spatial Perception battery (VOSP) and the Behavioural Assessment of the
Dysexecutive Syndrome (BADS), in addition to a plethora of individual tests.

The neuropsychological assessment can be combined with other investigations, such as video
telemetry or ambulatory EEG recordings, to investigate the cognitive correlates of unusual
EEG discharges or sub-clinical events.

Pre- and post-operative neuropsychological evaluation in epilepsy

Neuropsychological assessment has an important role in evaluating candidates for temporal
lobe surgery since the temporal lobes have long been implicated in memory functioning.
Bilateral hippocampal excision is associated with profound anterograde amnesia. Unilateral
resections are traditionally associated with material-specific memory dysfunction. The
traditional view is that the dominant temporal lobe (usually the left) is important for verbal
memory processing and the non-dominant temporal lobe (usually the right) for non-verbal or
visual memory processing. It is important to recognise that this model of memory function
suggests a specialisation of lateralised structures for verbal/visual material rather than an
exclusive function. Within this model, the aetiology of the seizure disorder and the underlying
pathology may play a critical role in shaping the nature and extent of pre- and post-operative
neuropsychological deficits. Different neuropsychological profiles are seen in patients with
developmental lesions, such as those associated with cortical dysgenesis, compared to those
with high-grade gliomas that develop in adulthood.

Post-operative deficits are dependent upon both the functional adequacy of the tissue
removed and the functional reserve of the remaining structures. Some plasticity and the
development of compensatory strategies post-operatively may also influence the nature and
extent of post-operative neuropsychological deficits. Pre-operative neuropsychological
scores, in conjunction with MRI and other clinical data, can be utilised to predict post-
operative neuropsychological change using logistic regression techniques. Patients at high
risk of a significant memory decline can be counselled pre-operatively and can be trained in
compensatory strategies prior to the surgery when appropriate.

The intracarotid amobarbital procedure (Wada Test)

The long running debate on the future of the intracarotid amobarbital procedure (IAP) or
Wada test (after Juhn Wada who first introduced it in 1949) and its role in the presurgical
assessment of prospective epilepsy surgery candidates is gradually resolving. Traditionally
the IAP was used to ensure that the memory capacity of the contralateral temporal lobe is
adequate to maintain useful memory functions unilaterally prior to surgery and it is an
effective test for language lateralisation. Recent studies have cast doubts on the reliability
and validity of the IAP in predicting post-operative amnesia. The testing protocol, choice of
behavioural stimuli, dosage and administration of the amytal and a host of factors related to
the individual’s reaction to the injection can interfere with the results, and many centres no
longer conduct Wada tests as part of a presurgical evaluation.4.5