- Email: [email protected]
SURGERY FOR TEMPORAL LOBE EPILEPSY
959 ROLE OF ROUTINE FUNCTIONAL BRAIN IMAGING IN TEMPORAL LOBE EPILEPSY
SiR,—Your editorials on surgery for temporal lobe epilepsy (Nov p 115) and single photon emission computed tomography (SPECT) and positron emission tomography (PET) in epilepsy (Jan 21, p 135) renew interest in the surgical treatment of epilepsy. You emphasise the need for simple and available methods for the localisation and lateralisation of temporal lobe epilepsy. The new 99mTc-labelled cerebral-blood-flow (CBF) tracers, such as hexamethylpropyleneamine oxime (HMPAO), permit the study of patients with epilepsy during or between seizures. We have studied six patients with focal temporal lobe epilepsy during the interictal phase. Every patient underwent a regional CBF (rCBF) and SPECT study with 99mTc-HMPAO and the 12,
results
were
correlated with those obtained from stable
an
alternative method to demonstrate abnormalities of CBF.l Both techniques gaave concordant results in all patients, especially in lateralisation of the abnormality. There was, however, a higher rate of mesial temporal lobe deficits detected with the 9’Tc-HMPAO technique. This agrees with the frequent presence of foci of sclerosis in the mesial aspect of the temporal lobe.2 It is worthwhile reporting a case of a 31-year-old man, who presented with attacks of epigastric aura, deja-vu, and loss of awareness followed by automatism since the age of 18. During the ictus a surface electroencephalogram suggested a right temporal focus. He was considered for right temporal lobectomy. However, following the concordant results of the rCBF/SPECT study with 99mTc-HMPAO and the stable xenon-enhanced CT, which depicted reduced rCBF in the contralateral temporal lobe, surgery was postponed for further investigation of the patient. Further PET studies of rCBF and metabolism confirmed that the focus was in the left temporal lobe. This small series and in particular the case described illustrates the clinical role of functional brain imaging and SPECT studies with 99mTC-HMPAO in the localisation of the abnormality in temporal lobe epilepsy. This methodology is generally available and cost-effective compared with the more cumbersome and less available PET.
Institute of Nuclear Medicine, University College and Middlesex School of Medicine, Mortimer Street, London W1N 8AA
referring patients and doing
Our
most
conservative estimate is that 2% of all
the stable
P. J. ELL D. C. COSTA
DJ, Zilkha E, Wise RJS, Kendall BE. Regional cerebral blood flow of patients with focal epilepsy studied using xenon enhanced CT brain scanning. J Neurol Neurosurg Psychiatry 1987; 50: 1584-88. 2 Engel J Jr, Brown WJ, Kuhl DE, Phelps ME, Mazziotta JC, Crandall PH. Pathological findings underlying focal temporal lobe hypometabolism m partial epilepsy. Ann Neurol 1982; 12: 518-28. 1. Fish DR, Lewis TT, Brooks
SURGERY FOR TEMPORAL LOBE EPILEPSY
StR,—A Lancet editorial’ suggested that at least 2000 patients with poorly controlled epilepsy in the UK might benefit from conventional temporal lobectomy. It is difficult to estimate the number of potential surgical cases because the care of patients with chronic epilepsy is scattered among different specialties, and epidemiological surveys of epilepsy have seldom provided adequate documentation of clinical characteristics, the results of appropriate investigations, or the long-term response to drug treatment. Since 1981 we have followed up prospectively all adults and children consecutively referred to an adult and paediatric epilepsy service with newly diagnosed, previously untreated epilepsy. Patients with progressive structural lesions have been excluded. In agreement with previous experience" the great majority do very well on medical treatment. Of 237 patients followed up for two or more years, 33 have not responded to optimum drug therapy and have an intractable seizure disorder. 15 of these have complex partial seizures, and all are experiencing at least one seizure a month. 5 patients (2% of the total) have a unilateral temporal lobe focus on
new cases
of
epilepsy referred to neurology or paediatric outpatient departments will become potential candidates for presurgical evaluation. The annual incidence of epilepsy is 50 per 100 000,3 implying 500 new surgical cases every year in the UK. At present no more than 200 cases are being assessed each year (C. E. Polkey, personal communication). This may be due to a lack of specialised facilities to undertake such assessments or to an unwillingness of physicians to refer cases. Our findings suggest that the accumulating number of potential surgical candidates is likely to be greatly in excess of 2000.
xenon-
enhanced computed tomography (CT) and rCBF studies,
We thank Dr D. R. Fish for xenon-enhanced CT.
patients have generalised epileptiform abnormalities, 4 have epileptic activity confined to one hemisphere, 1 patient has a frontal lobe focus, and 1 patient has had repeatedly normal interictal EEGs. the interictal EEG. A further 4
Department of Neurology, King’s College Hospital, London SE5 9RS
R. D. C. ELWES M. DE SILVA E. H. REYNOLDS
1. Editonal. Surgery for temporal lobe epilepsy. Lancet 1988; ii: 1115. 2. Elwes RDC, Johnson AL, Shorvon SD, Reynolds EH The prognosis for seizure control in newly diagnosed epilepsy. N Engl J Med 1984, 311: 944-47. 3. Hauser WA, Kurland LT. The epidemiology of epilepsy in Rochester, Minnessota, 1935 through 1967. Epilepsia 1975, 16: 1-66.
NEUROLOGICAL COMPLICATIONS AFTER SIMULTANEOUS IMMUNISATION AGAINST TICK-BORNE ENCEPHALITIS AND TETANUS
SIR,-Neurological complications of tetanus toxoid injections are very rare and mainly affect the peripheral nervous system. There are, however, isolated reports of optic neuritis, accommodation
disturbances, and encephalopathy.l,2 Vaccination against tickborne encephalitis (TBE) is also thought to be safe, though we have reported one case of polyneuritis.3 In June, 1988, we saw a 50-year-old man with no history of disease. 1 day after a tick bite in a non-endemic area he was vaccinated simultaneously with 0-35 ug TBE virus antigen and 75 IU tetanus toxoid. He responded with fatigue, muscle weakness, and joint pain which lasted for about 2 days. 4 days after vaccination he had hiccups with left facial weakness, left faciobrachial sensory deficits, and a fluctuating slowing of psychomotor function, disorientation, and memory deficits. These symptoms were still present on admission 8 days after vaccination. The site of the tick bite (on his left hip) and the vaccination sites on both arms were unreactive. Electroencephalography revealed an intermittent right temporal and parietal focus. Computerised tomographic scans revealed a 3 cm lesion in the right caudate and lentiform nucleus with typical features of ischaemic infarction. Magnetic resonance imaging indicated an additional 0-3 cm white-matter lesion in the left parietal centrum semiovale. Ultrasound study of the cranial arteries was normal. Latencies of visual evoked potentials were slightly increased on both sides. Evoked potentials of the median and tibial nerve were normal. The CSF, 9 days after vaccination, contained 3 cells1 with an increased proportion of reactive lymphocytes and single plasma cells. The CSF albumin (449 mg/1) and IgG (70 mg/ml) indicated a disturbed blood-brain barrier. The IgG index was normal and there were no oligoclonal bands. TBE virus IgG antibody in serum was positive at 130, 340, 240, and 340 Vienna IU 1, 3, 8, and 32 weeks, respectively, after vaccination; specific IgM was consistently negative. Lymphocyte transformation tests with TBE antigen 3, 8, and 32 weeks after vaccination gave stimulation indexes of 2, 6, and 4, respectively 32 weeks after vaccination, tetanus toxoid antigen yielded a stimulation index of 7-5. Serological tests for neurotropic viruses, Treponema pallidum, Borrelia burgdorferi, Toxoplasma gondii, and Listeria monocytogenes were negative. The patient recovered without specific therapy and 8 weeks after vaccination his neurological status and EEG were normal. Slight lability of mood was the only residual symptom. 32 weeks after vaccination MRI indicated an ischaemic defect in the right basal ganglia. The small left parietal white-matter lesion was unchanged. TBE
can
area, the
be
man
excluded; the tick-bite occurred in a non-endemic
had
IgG immunity against
TBE virus and
no
IgM
SiR,—Your editorials on surgery for temporal lobe epilepsy (Nov p 115) and single photon emission computed tomography (SPECT) and positron emission tomography (PET) in epilepsy (Jan 21, p 135) renew interest in the surgical treatment of epilepsy. You emphasise the need for simple and available methods for the localisation and lateralisation of temporal lobe epilepsy. The new 99mTc-labelled cerebral-blood-flow (CBF) tracers, such as hexamethylpropyleneamine oxime (HMPAO), permit the study of patients with epilepsy during or between seizures. We have studied six patients with focal temporal lobe epilepsy during the interictal phase. Every patient underwent a regional CBF (rCBF) and SPECT study with 99mTc-HMPAO and the 12,
results
were
correlated with those obtained from stable
an
alternative method to demonstrate abnormalities of CBF.l Both techniques gaave concordant results in all patients, especially in lateralisation of the abnormality. There was, however, a higher rate of mesial temporal lobe deficits detected with the 9’Tc-HMPAO technique. This agrees with the frequent presence of foci of sclerosis in the mesial aspect of the temporal lobe.2 It is worthwhile reporting a case of a 31-year-old man, who presented with attacks of epigastric aura, deja-vu, and loss of awareness followed by automatism since the age of 18. During the ictus a surface electroencephalogram suggested a right temporal focus. He was considered for right temporal lobectomy. However, following the concordant results of the rCBF/SPECT study with 99mTc-HMPAO and the stable xenon-enhanced CT, which depicted reduced rCBF in the contralateral temporal lobe, surgery was postponed for further investigation of the patient. Further PET studies of rCBF and metabolism confirmed that the focus was in the left temporal lobe. This small series and in particular the case described illustrates the clinical role of functional brain imaging and SPECT studies with 99mTC-HMPAO in the localisation of the abnormality in temporal lobe epilepsy. This methodology is generally available and cost-effective compared with the more cumbersome and less available PET.
Institute of Nuclear Medicine, University College and Middlesex School of Medicine, Mortimer Street, London W1N 8AA
referring patients and doing
Our
most
conservative estimate is that 2% of all
the stable
P. J. ELL D. C. COSTA
DJ, Zilkha E, Wise RJS, Kendall BE. Regional cerebral blood flow of patients with focal epilepsy studied using xenon enhanced CT brain scanning. J Neurol Neurosurg Psychiatry 1987; 50: 1584-88. 2 Engel J Jr, Brown WJ, Kuhl DE, Phelps ME, Mazziotta JC, Crandall PH. Pathological findings underlying focal temporal lobe hypometabolism m partial epilepsy. Ann Neurol 1982; 12: 518-28. 1. Fish DR, Lewis TT, Brooks
SURGERY FOR TEMPORAL LOBE EPILEPSY
StR,—A Lancet editorial’ suggested that at least 2000 patients with poorly controlled epilepsy in the UK might benefit from conventional temporal lobectomy. It is difficult to estimate the number of potential surgical cases because the care of patients with chronic epilepsy is scattered among different specialties, and epidemiological surveys of epilepsy have seldom provided adequate documentation of clinical characteristics, the results of appropriate investigations, or the long-term response to drug treatment. Since 1981 we have followed up prospectively all adults and children consecutively referred to an adult and paediatric epilepsy service with newly diagnosed, previously untreated epilepsy. Patients with progressive structural lesions have been excluded. In agreement with previous experience" the great majority do very well on medical treatment. Of 237 patients followed up for two or more years, 33 have not responded to optimum drug therapy and have an intractable seizure disorder. 15 of these have complex partial seizures, and all are experiencing at least one seizure a month. 5 patients (2% of the total) have a unilateral temporal lobe focus on
new cases
of
epilepsy referred to neurology or paediatric outpatient departments will become potential candidates for presurgical evaluation. The annual incidence of epilepsy is 50 per 100 000,3 implying 500 new surgical cases every year in the UK. At present no more than 200 cases are being assessed each year (C. E. Polkey, personal communication). This may be due to a lack of specialised facilities to undertake such assessments or to an unwillingness of physicians to refer cases. Our findings suggest that the accumulating number of potential surgical candidates is likely to be greatly in excess of 2000.
xenon-
enhanced computed tomography (CT) and rCBF studies,
We thank Dr D. R. Fish for xenon-enhanced CT.
patients have generalised epileptiform abnormalities, 4 have epileptic activity confined to one hemisphere, 1 patient has a frontal lobe focus, and 1 patient has had repeatedly normal interictal EEGs. the interictal EEG. A further 4
Department of Neurology, King’s College Hospital, London SE5 9RS
R. D. C. ELWES M. DE SILVA E. H. REYNOLDS
1. Editonal. Surgery for temporal lobe epilepsy. Lancet 1988; ii: 1115. 2. Elwes RDC, Johnson AL, Shorvon SD, Reynolds EH The prognosis for seizure control in newly diagnosed epilepsy. N Engl J Med 1984, 311: 944-47. 3. Hauser WA, Kurland LT. The epidemiology of epilepsy in Rochester, Minnessota, 1935 through 1967. Epilepsia 1975, 16: 1-66.
NEUROLOGICAL COMPLICATIONS AFTER SIMULTANEOUS IMMUNISATION AGAINST TICK-BORNE ENCEPHALITIS AND TETANUS
SIR,-Neurological complications of tetanus toxoid injections are very rare and mainly affect the peripheral nervous system. There are, however, isolated reports of optic neuritis, accommodation
disturbances, and encephalopathy.l,2 Vaccination against tickborne encephalitis (TBE) is also thought to be safe, though we have reported one case of polyneuritis.3 In June, 1988, we saw a 50-year-old man with no history of disease. 1 day after a tick bite in a non-endemic area he was vaccinated simultaneously with 0-35 ug TBE virus antigen and 75 IU tetanus toxoid. He responded with fatigue, muscle weakness, and joint pain which lasted for about 2 days. 4 days after vaccination he had hiccups with left facial weakness, left faciobrachial sensory deficits, and a fluctuating slowing of psychomotor function, disorientation, and memory deficits. These symptoms were still present on admission 8 days after vaccination. The site of the tick bite (on his left hip) and the vaccination sites on both arms were unreactive. Electroencephalography revealed an intermittent right temporal and parietal focus. Computerised tomographic scans revealed a 3 cm lesion in the right caudate and lentiform nucleus with typical features of ischaemic infarction. Magnetic resonance imaging indicated an additional 0-3 cm white-matter lesion in the left parietal centrum semiovale. Ultrasound study of the cranial arteries was normal. Latencies of visual evoked potentials were slightly increased on both sides. Evoked potentials of the median and tibial nerve were normal. The CSF, 9 days after vaccination, contained 3 cells1 with an increased proportion of reactive lymphocytes and single plasma cells. The CSF albumin (449 mg/1) and IgG (70 mg/ml) indicated a disturbed blood-brain barrier. The IgG index was normal and there were no oligoclonal bands. TBE virus IgG antibody in serum was positive at 130, 340, 240, and 340 Vienna IU 1, 3, 8, and 32 weeks, respectively, after vaccination; specific IgM was consistently negative. Lymphocyte transformation tests with TBE antigen 3, 8, and 32 weeks after vaccination gave stimulation indexes of 2, 6, and 4, respectively 32 weeks after vaccination, tetanus toxoid antigen yielded a stimulation index of 7-5. Serological tests for neurotropic viruses, Treponema pallidum, Borrelia burgdorferi, Toxoplasma gondii, and Listeria monocytogenes were negative. The patient recovered without specific therapy and 8 weeks after vaccination his neurological status and EEG were normal. Slight lability of mood was the only residual symptom. 32 weeks after vaccination MRI indicated an ischaemic defect in the right basal ganglia. The small left parietal white-matter lesion was unchanged. TBE
can
area, the
be
man
excluded; the tick-bite occurred in a non-endemic
had
IgG immunity against
TBE virus and
no
IgM