Epilepsy is one of the commonest serious neurological conditions in most countries and this undoubtedly true in Africa. Recent epidemiological studies carried out in Kenya (FEKSI et all 1991) shows that the incidence of epilepsy is around two percent, much higher than in the western countries. Studies in four developing countries, Ecuador, Kenya, the Philippines and Pakistan have shown that only a small proportion of patients (8-20%) with active epilepsy are at any one time actually receiving drug treatment. The reason for this failure of treatment are complex, and may involve such no-pharmacological aspects as cultural attitudes to treatment, the acceptability of drugs as a method of treatment, the cost of treatment, and the system for the delivery of health care. In many developing countries there is a shortage of medical manpower and a lack of well organised system of referral, records or health care delivery. The high proportion of untreated epileptic patients may be the cause of the high number of intractable epilepsies seen in the developing countries.
The primary therapy for patients suffering for any type of epileptic seizures is medical: anticonvulsive therapy, psychotherapy and social and occupationalrehabilitaion. If the epilepsy is only syptomatic evidence of a progressive lesion of the brain, such as neoplasms, abscesses, haematomas, vascular malformations, congenital or other infective lesions appropriate surgical measures are imperative: we have a large series of these secondary epilepsies but we will not consider them in this paper. In chronic epilepsies, medical treatment should be given a fair trial and considered unsucceessful only when all drugs appropriate to the type of epilepsy have been given alone or in a combination to toxic limits. Such anti-convulsive medication will control the attacks in more than fifty per cent of cases and markedly decrease the seizures in anotlier 25 per cent of cases, thus only 20-25% of the epileptics may become candidates for surgical intervention. The preliminary criteria to be satisfied to consider an epileptic patient for surgical treatment are insufficiency of the pharmacotherapy, the evidence of an organic brain lesion and the handicapping characters of the seizures. Two main groups of surgical approaches are recognised: the first aims at suppressing the seizures by resecting the primary epileptogenic focal area (topectomy, lobectomy, hemispherectorny): the second approach aims only at reducing the epileptogenicity by preventing the diffusion of the epileptic discharges, by enhancing inhibiting or by reducing facilitatory influences (cingulectomy, callosotomy, electrical stimulation of the cerebellum, stereotactic deep lesions and others). In general, surgical procedures that aim to remove epileptogenic tissue together with any identifiable lesion are more common and more successful than those that attempt to modify brain activity.
Some neurosurgeons find the subject of epilepsy of no special interest and operations for its relief do not excite them as much as complicated surgical procedures for vascular malformations or particularly difficult tumours. That is not my case: I had my neurosurgical training and worked for fifteen years at the Neurosurgical Institute of the Medical School, University of Padua, Italy, where the surgery of epilepsy was highly advanced, so far that when I left the Institute to start pioneering neurosurgery in Kenya, the Institute of Padua was amongst the highest recognized centres for the treatment of epilepsy. When I started single handed neurosurgery in East Africa in 1967, the load of neurosLirgical work was such that for several years I did little in the field of surgery of chronic intractable epilepsies also because of lack of EEG services, difficulties with neuroradiological investigations and mainly because of other priorities in the neurosurgical field. With improved EEG services and neuroimaging facilities later on my interest in the surgery of epilepsy revived.
At the present time, we are sing only two surgical approaches to the treatment of medically intractable epilepsy. One is the older approach of resection of an epileptic focus, and the other is a newer procedure of division of all or a portion of the corpus callosum (Callosotomy). Several other procedures mentioned before and enjoying popularity in the past, including cyngulectomy, cerebellar stimulation, streotactic subcortial lesions and others have now been abandoned. Of the two surgical options in common use now, resection of the epileptic focus has a much higher probability of completely controlling the seizures, thus, the initial evaluation of patients with medically intractable epilepsy should be directed at establishing whether they are candidates for resective surgery.
For the selection of patients for resective surgery we follow the classic criteria enumerated by the Montreal School. A focus of origin of the seizures must be identified, and that focus must be in an area of brain where the resection is not likely to lead to an unacceptable neurological deficit: resection is not advisable in the sensorimotor area if a hemiparesis is not already present, or in areas essential for speech or recent memory. The basic lines of inquiries used in our clinic are the following: accurate clinical history and neuropyschological examination (patients should be asked clinical features of their attacks, which will give a clue to the origin; should be asked about interictal events, about past medical history, which may reveal an event sufficient to cause brain damage (as for localized head injuries) and hence the seizures. Other clinical details such as family, developmental, educational and psychiatric history should be investigated - The neurological examination is often negative. EEG examinations: serial EEG is obtained to localize a cortical epileptogenic area if possible. Recordings during drowsiness and sleep (or activation) and sphenoidal electrodes placements are frequently useful. Brain imaging: Computed tomography (CT) scanning makes the detection of small discrete lesions more likely. The CTScans following contrast enhancement of the cerebro spinal fluid with metrizanide may be useful to detect some lesions at the level of the temporal lobe of the lateral ventricles. The magnetic resonance imaging (MRI) detect even greater proportions of such lesions, and is essential in the surgical treatment of epilepsy.
The greatest number of intractable epilepsies operated in Kenya are partial post traumatic epilepsies. In the aetiology of partial epilepsy there is a great number of head injuries, particularly depressed skull fractures, unduly common in East Africa. These localized trauma are caused mainly by road traffic accidents and also very common by assaults with a paiiga (a sort of machete in large use mainly in the rural areas) or other sticks. These depressed skull fractures are often incorrectly treated in the peripheral hospitals of the country, laeding to a meningo-cerebral scar that is highly epileptogenic, leading often to an intractable epilepsy. I will recall here the case of a taxi driver involved in an assault in which he had a bad left frontal depressed skull fracture for which he was surgically treated. Seven months later he became a post-traumatic epileptic and his epilepsy became intractable: he could not work and he and his family were facing misery. He came to see me and after all the routine investigations, we excised the left frontal brain scar. As a result of this, he has had no more epileptic fits since 8 years, back happily to his job of driving taxis and I use him often if I need a taxi. Examples as this one are plenty in East Africa and in the whole of Africa and I see no reason and no particular difficulty in treating this type of epilepsies also without sophisticated equipment. We have operated 64 cases of focal post traumatic intractable epilepsy with good results and in over fifty per cent of cases the treatment has been stopped, and acceptable results in the other where the epilepsy is well controlled on medical treatment. In the aetiology of partial epilepsy there is also a relatively high number of patients with either a history of birth trauma, again very frequent in East Africa, or infective or congenital neurological damage. It is often impossible in retrospect to distinguish which of this factors is responsible for the neurological damage but perhaps there is a higher incidence of birth trauma in Africa because of inadequate obstetric services. We have found 19 cases of mesial temporal sclerosis with intractable epilepsy in whom we performed a temporal lobectomy with considerable clinical and EEG improvement in all cases. In seven cases of infantile hemiplegia with pharmacoresistant epilepsy and severe behavioral changes we performed a hemispherectomy with good results in the control of the seizures and a considerable improvement of the behaviour.
Since a few years, we have adopted the callosotorny in the non focal intractable epilepsy: the indications were intractable epilepsies associated with injuries and usually characterized by drop attacks of the tonic or atonic types often accompanied by generalized tonic clonic convulsions in patients in whom there was no evidence for well defined removable epileptogenic focus after standard EEG and CT Scan investigations. We usually perform, and anterior callosotomy of 4-6 cm depending on the gravity of the symptoms. We have operated 7 cases with important reduction on the drop attacks, a certain improvement of the control of the epilepsy with medication. We have observed some transient episodes of mutism and akinesia due most probably to interference with cingulate gyri with disruption of cingulum fibres bilaterally. Our experience is limited but the feeling is that perhaps more patients may benefit from this type of surgery. We have no experience at all in subpial transections.
Out of 97 patient operated in Kenya for intractable epilepsy we have had no surgical mortality and no relevant morbidity. Improvement in instrumentation, electrophysiological methods and surgical techniques when combined with more precise selection of patients may be expected to provide more benefits in the future. The rationale for surgical excision in epilepsy, therefore, is based on the concept that the removal of a part of an epileptogenic area is rarely effective, but excision of most of this may lead to progressive disappearance of the seizure tendency. RASMUSSEN emphasised the concept that extensive epieptic activity may interfere with the function of the rest of the brain and that the removal of the epileptogenic focus may improve brain function and that the scar of the surgical excision rarely becomes epileptogenic if scrupulous care is taken to preserve the pial surface at the margins of the excision. In conclusion, even in Tropical Africa, we have today in many centres better tools and surgical experience than when the surgery of epilepsy started with PENFIELD and we can help more and more intractable epileptics in this part of the world.