EEG is a test which records the electrical activity
of the brain. It is the ‘gold standard’ for the diagnosis of epilepsy.
(EMG)/Nerve Conduction (NCS)
Nerve Conduction Studies and electromyography
evaluate the integrity of the nervous system and are an essential component of a
neurological exam when sensation or motor pathways are impaired.
Evoked potential testing utilizes various sensory
stimuli to evoke a brain response that provide information about the integrity
of various sensory pathways.
The TCD test evaluates the velocity of blood flow in
the vessels of the brain using ultrasound waves. The test is used to monitor the
progress of patients following subarachnoid hemorrhage, clipping and aneurisms
or other cerebrovascular events.
Monitoring of the nervous system is needed for several procedures,
both neurological and orthopaedic. During surgery to remove the focal part of
the brain that is the major source of electrical disruption, an EEG is performed
by recording directly on the brain. IOM is also used during orthopaedic
procedures such as corrective scoliosis and selective posterior rhizotomy, and
is used to monitor both sensory and motor nerves.
Video EEG Monitoring
When medications are not effective in people with
epilepsy (a condition known as refractory or intractable epilepsy), a higher
level of diagnostic care and treatment is called for. In such cases, patients
are admitted to the hospital for video EEG monitoring.
During this procedure, patients are connected to EEG monitoring equipment.
The equipment receives the EEG read-out, translates it to digital format and
merges it with simultaneous digital video recording, allowing for a continuous
record of seizures over several days. A technologist monitors the recording,
and an online computer monitors the EEG changes. Such monitoring allows the
physician to diagnose the type, frequency, and precise location of patients'
The Saskatchewan Epilepsy Program is
part of a collaborative partnership including the Division of Neurosurgery and
the Division of Neurology, working together to provide hope for adults and
children with epilepsy in the province of Saskatchewan.
In most patients, seizures can be adequately controlled with antiepileptic
medications. However, in 40% of patients with seizure disorders, seizures are
resistant to medical therapy. For some of these patients, surgery has the
possibility of providing a complete cure of their epilepsy in some cases. Each
patient under consideration for surgery participates in a thorough evaluation at
the Royal University Hospital prior to surgery.
The electroencephalograms (EEGs) of patient candidates are often recorded and
analyzed in the Epilepsy Monitoring Laboratory, which helps to classify the type
and the locations of the observed seizures. In addition, brain imaging studies
including MRI scans, and SPECT scans may be used together.
Patient specific conferences are held with the
group for possible surgical candidates. All potential candidates are evaluated
first by Dr. Tellez-Zenteno (adults) and Dr. Lowry (children).
Vagus nerve stimulation is a
therapy for treating seizures that are resistant to conventional epilepsy
medications. VNS involves placement of a small stimulator under the skin in the
chest. The stimulator is attached to a small lead which is then attached to the
vagus nerve in the neck. The stimulator provides a light electrical signal on
and off throughout the day. In many patients, this causes a substantial
improvement in seizure frequency and severity.
For selected patients with difficult to control
epilepsy, a ketogenic diet provides improved seizure control. Dr. Lowry, Dr
Tellez and a registered dietitian work closely together to determine which
patients might benefit from the diet, to educate the parents about the diet, and
to help the parents initiate and manage the diet. Initial evaluation is through
the Pediatric Neurology Clinic.
Referrals to the dietitian come only from the
pediatric and adults neurologists. After a referral, the parents meet the
dietitian to discuss the specifics of the diet. After the diet is begun, usually
in an inpatient setting, the dietitian and neurologists continue to work with
the parents to maximize the benefit from the diet
Medication is widely used as the first step in
treatment of epilepsy. Dr. Lowry and Dr. Tellez-Zenteno use their in-depth
knowledge of the latest drug therapies available to treat patients depending on
the type and frequency of the patients' seizures. This knowledge is essential in
optimally treating patients with epilepsy, as eight new medications have been
released in the past few years.
Neuropsychological testing measures a patient's
memory and cognition. The most familiar example is the IQ test.
Neuropsychological testing can sometimes help identify areas of the brain that
are not functioning normally. Dysfunction may provide a clue as to the area of
seizure onset. For example, impaired memory for word lists may indicate abnormal
language dominant temporal lobe function.
Because one risk of epilepsy surgery is its effects on memory and cognition,
baseline neuropsychological testing is an important component in pre-surgical
evaluation. Neuropsychological testing for epilepsy surgery evaluation takes
four hours. Neuropsychological testing is done by Dr. Mirna Vrbancic (www.medicine.usask.ca/psychiatry/people/part-time-faculty-consultants/vrbancic-m-1).
WADA (intracarotid amobarbital) tests are performed
at RUH to determine hemispheric language dominance and to determine whether a
single hemisphere is capable of supporting memory.
While commonly ordered as part of an epilepsy
surgery investigation, WADA testing is occasionally obtained as a pre-operative
planning tool in patients being evaluated for tumor or vascular anomaly
resection. Wada testing is a complex activity that requires multiple individuals
from different departments to work together as an integrated team.