Seizure improvement and reduction of bisynchronous discharges after corpus callosotomy has been well documented. Between 50 \200\22380 % of the patients who underwent callosotomy hav e at least 50 % seizure reduction (51, 55, 61 \200\22364). Atonic seizures usually respond best to callosotomy compared to other types of seizures (53) while focal motor seizures rec eive the least bene \201 t. Partial seizures can be worsened and sometimes new types of se izures can emerge after callosotomy, especially in patients with independent bifrontal epil eptogenic foci (60, 65, 66). A variety of techniques of corpus callosotomy have been described over the years. The moder n techniques are mainly restricted to division of the corpus callosum and the hippocampal c ommissure (52). However, how much of the structure is divided remains unclear. Some studies showed that the extent of callosal sections correlated with seizure outcome and, therefore , more extensive sections yielded better results (53 \200\22357). Other studies Several studies have investigated prognostic factors for callosot- omy outcomes. The result s from these studies, however, are con- \202 icting. For example, a few studies did not \201 nd age at seizure onset or at the time of surgery to have prognostic signi \201 canc e (58, 59, 62) whereas other studies suggest that younger age at the time of sur- gery or e arlier seizure onset have better outcomes including improvement in quality of life, family satisfaction, and fewer com- plications (67, 68). The presence of signi \201 cant cognitiv e impair- ment and/or mixed cerebral dominance are associated with poor outcome in a few st udies (58, 60, 67, 69). However, these \201 ndings have not been con \201 rmed by others (59, 70, 71). Moreover, recent series of callosotomy in children with severe mental retard ation demonstrate favorable results (61, 72). Ictal and interictal EEG have been found to b e prognostically useful in some studies (59, 67, 70, 71, 73). Ictal patterns of generalized slow spike wave dis- charges, electrodecrement, and non-evolving low amplitude fast activi ty have been associated with excellent outcomes (71). A few studies have shown that bilater al independent spikes are indicative of poor outcomes after callosotomy (67, 73). Disruptio n of syn- chrony as well as reduction of generalized bilateral synchronous spikes in the in traoperative or postoperative electroencephalogram (EEG) recordings are good indicators for favorable outcomes (59, 70). Some studies, however, have not found clear relationships bet ween EEG \201 ndings and outcomes after callosotomy (74, 75). Box 31.2 Candidates for corpus callosotomy Intractable generalized seizures with: \227\206 Drop attacks \227\206 Generalized tonic \200\223clonic seizures \227\206 Myoclonic seizures \227\206 Other major motor manifestations. Patients with diffuse or multifocal pathologies, e.g.: \227\206 Rasmussen \200\231s encephalitis \227\206 Lennox \200\223Gastaux syndrome \227\206 Sturge \200\223Weber syndrome \227\206 Tuberous sclerosis. oxford textbook of epilepsy and epileptic seizures 332 Corpus callosotomies can result in acute as well as chronic dis- connection syndromes. In t he acute setting, an apathetic mutism lasting days to weeks can occur, usually related to t he extent of cal- losal section. Other de \201 cits including hemiparesis and a variety of apraxias can also occur. In the chronic setting, de \201 cits can be more subtle. Poor na ming of objects in the dominant hemi \201 eld or of those held in the dominant hand can be observed. This is most likely due to a disruption of the pathways from the non-dominant he misphere where sensation or vision is perceived, to the domi- nant hemisphere where languag e is necessary to express receipt of these inputs. Several other, more subtle de \201 cits of motor, language and other functions may also exist. Box 31.3 Candidates for hemispherectomy a \227\206 Infantile spasms due to focal lesions (localization related) \227\206 Rasmussen \200\231s encephalitis \227\206 Sturge \200\223Weber syndrome \227\206 Hemispheric malformations of cortical development such as hemimegalencephaly, sch izencephaly, and cortical dysplasia involving signi \201 cant region of a hemisphere. \227\206 Porencephaly syndrome \227\206 Hemiplegia hemiconvulsion epilepsy syndrome (HHE). a There may be overlap between these categories. Hemispherectomy When seizures arise from multiple regions in one hemisphere, removal of the abnormal hemisphere seems a logical approach to getting rid of seizures. Drastic as this m ight seem, applied to the correct clinical situations and with the right expertise, it is a dra- matically effective intervention in many, both in the short and long term. Seizure fr eedom and cognitive outcomes can be impressive with postoperative de \201 cits that are ac ceptable enough to allow functionality. ipsilateral temporal lobe. The extent of the resection can vary to include the superolatera l frontal and parietal lobes but the poste- rior quadrant and anterior frontal lobes are us ually left intact. The blood supply to these structures is left undisturbed. The entire cor pus callosum is disconnected as are the white matter connec- tions of the remaining frontal lobe and the parietal and occipital lobes. The ipsilateral cingulate gyrus is also disconn ected. Complete disconnection can be technically dif \201 cult to achieve and up to a \201 fth of patients are subsequently found to have incomplete discon- nections, many of wh om continue to have seizures (84). Anatomical hemispherectomy, where the entire hemisphere is removed, was successfully perfor med with encouraging results in the late 1960s (76). However, severe late complications inc luding hydrocephalus and super \201 cial haemosiderosis occurred in up to one-third of the patients (77, 78). In order to reduce the risk of postoperative complications, several tec hnical modi \201 cations of hemispherectomy have been introduced, variously referred to as functional hemispherectomy, hemispherotomy, hemicorticec- tomy, peri-insularhemispherotomy , and hemispheric deafferenta- tion (79). In these, the anatomical cortical resection is su btotal rather than total but coupled with a physiological hemispherec- tomy where deafferen tation or disconnection is carried out. This approach of \200\230functional \200\231 hemis pherectomy is to minimize cortical resection and functionally isolate abnormal hemisphere b y dis- rupting neuronal \201 bre connections (80). A large meta-analysis of data from 11 epilepsy centers demonstrated that the new tech- niques that focused on disconnection were as good or slightly better with a clear bene \201 t in perisurgical morbidity compared to the old techniques involving large resections (79). Although anatomical hemispherectomies a re now rare in epilepsy surgery practice, these are still used in patients who failed funct ional hemi- spherectomies where there is a strong case for epilepsy arising from remnant br ain tissue. Peri-insular hemispherotomy and hemispheric deafferentation both emphasize disconnection. T he former uses a peri-insular, suprasylvian and infrasylvian approach to a transventricular corpus callosotomy and removal of the mesial temporal structures. The latter uses a standa rd temporal lobectomy for ventricular access and subsequent callosotomy. Hemidecortication is an infrequently used technique where gray matter is removed or \200\230degloved \200 \231 from underlying white matter. The overall rates of complete or near complete seizure freedom vary between 50 \200\22394 % (85 \200\22387). Seizure outcome is in \202 uenced by Hemispherectomy is most often performed in the pediatric population and is indicated in med ical refractory epilepsy with extensive or multiregional epileptogenic foci in a single hem isphere (Box 31.3 ). However, the criteria for patient selection are still in evolution (81 ). Studies have suggested that patients with asymmet- ric MRI abnormalities, where one abno rmal side predominates over the other, might still be bene \201 t from hemispherectomy (82 ). Nonetheless, patients without contralateral MRI lesions usually have better seizure outc ome and cognitive development after surgery (83). Fig. 31.5 Functional hemispherectomy in a 10-year-old patient with Rasmussen \200\231s ence phalitis showing complete removal of the frontal, parietal, and temporal lobes with intact left posterior quadrant and basal ganglia structures. The resection here has been extended to include the entire frontal lobe. Functional hemispherectomy (Fig. 31.5) involves removal of the central part of the hemisphe re (the frontal and parietal opercula, including the inferolateral frontal and parietal lob es) and the CHAPTER 31 other surgeries for epilepsy and new approaches 333 brain pathology, surgical technique, the completeness of discon- nection, and the extent of resection. Patients with Sturge \200\223Weber syndrome usually have excellent results wher eas patients with hemimegalencephaly frequently have poor outcomes (88). A recent study com paring peri-insular hemispherotomy and hemidecorti- cation suggested that peri-insular hemi spherotomy provided better seizure outcomes (89). Moreover, a high seizure freedom rate has been reported in patients whose deep structures were removed or disconnected (90, 91). 5. Hufnagel A , Zentner J , Fernandez G , Wolf HK , Schramm J , Elger CE . Multiple subpial transection for control of epileptic seizures: effectiveness and safety . Epilepsia 1997 ; 38 , 678 \200\223 88 . 6. Mulligan LP , Spencer DD , Spencer SS . Multiple subpial transections: the Yale experience . Epilepsia 2001 ; 42 : 226 \200\223 9 . 7. Schramm J , Aliashkevich AF , Grunwald T . Multiple subpial transections: outcome and complications in 20 patients who did not undergo resection . J Ne urosurg 2002 ; 97 : 39 \200\223 47 . 8. Blount JP , Langburt W , Otsubo H , Chitoku S , Ochi A , Weiss S , et al . Multiple subp ial transections in the treatment of pediatric epilepsy . J Neurosurg 2004 ; 100 : 118 \200\223 24 . Although the ideal timing of hemispherectomy is unclear, key considerations are seizure-rel ated morbidity and neuropsychologi- cal morbidity from epilepsies that are often extremely detrimental to brain development. Equally, the presence or absence of potential brain plast icity for certain brain functions is an important consid- eration. For example, removal or disconnection of the language areas as part of a dominant hemispherectomy in a 2-year-old c hild can result in reasonable relocation of language function to the con- tralateral, intac t hemisphere. This is less likely in a 10-year-old and highly unlikely in an adult. Proxima l limb power can also recover to some extent, enough to allow ambulation in many, but dista l limb power and \201 ne \201 nger movements do not return. Studies have shown bene \201 t in psychosocial and intellectual functions in patients who underwent surgery early ( 92 \200\22394). In Rasmussen \200\231s encephalitis, it is clear that a shorter period from seizure onset to surgery is asso- ciated with better seizure outcome (95). However, in som e patients a longer preoperative period might enhance brain plasticity and result in better motor outcomes (96). In general, the bene \201 ts of early hemispherectomy must be weighe d against postoperative de \201 cits (97). A more recent study of hemispherectomy has demo nstrated favorable outcome with low morbidity in adults as well (98). 9. Moo LR , Slotnick SD , Krauss G , Hart J . A prospective study of motor recovery followi ng multiple subpial transections . Neuroreport 2002 ; 13 : 665 \200\223 9 . 10. Leonhardt G , Spiekermann G , Muller S , Zentner J , Hufnagel A . Cortical reorganization following multiple subpial transection in human brain \200\224 a s tudy with positron emission tomography . Neurosci Lett 2000 ; 292 : 63 \200\223 5 . 11. Shimizu T , Maehara T , Hino T , Komori T , Shimizu H , Yagishita A , et al . Effect of multiple subpial transection on motor cortical excitability in cortical dysgenesis . Brain 2001 ; 124 : 1336 \200\223 49 . 12. Wyler AR , Wilkus RJ , Rostad SW , Vossler DG . Multi ple subpial transections for partial seizures in sensorimotor cortex . Neurosurgery 1995 ; 37 : 1122 \200\223 7; discussion 27 \200\2238 . 13. Smith MC . Multiple subpial transection in patients with extratemporal epilepsy . Epilepsia 1998 ; 39( Suppl 4 ): S81 \200\223 9 . 14. Shimizu H , Maehara T . Neuronal disconnection for the surgical treatment of pediatric epilepsy . Epilepsia 2000 ; 41(Suppl 9 ): 28 \200\223 30 . 15. Devinsky O , Romanelli P , Orbach D , Pacia S , Doyle W . Surgical treatment of multifocal epilepsy involving eloquent cortex . Epilepsia 2003 ; 44 : 718 \200\223 23 . 16. Spencer SS , Schramm J , Wyler A , O \200\231Connor M , Orbach D , Krauss G , et al . Multiple subpial transection for intractable partial epilepsy: an international met a-analysis . Epilepsia 2002 ; 43 : 141 \200\223 5 . 17. Orbach D , Romanelli P , Devinsky O , Doyle W . Late seizure recurrence Conclusion Multiple subpial transection can provides a surgical option to patients with int ractable focal epilepsy who are otherwise not ame- nable candidates for resective surgery. The application of the con- cept of multiple subpial transection to the hippocampus, throug h multiple hippocampal transection, is a potentially good alternative for high-functioning patients with mesial temporal lobe epilepsy. For devastating epilepsy, corpus callosotomy c an be a good pallia- tive option that can help improve the patient \200\231s quality of lif e. Hemispherectomy procedures can be extremely effective in other- wise devastating childho od epilepsies. Recent technical modi \201 ca- tions of hemispherectomy have made the techn ique safer and more appealing. 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As a whole, this corresponds to at least 1 \200\2232 % of ED admission s ( 2 ). The most common seizure type is the pediatric febrile convulsion, affecting up to 4 % of children between 6 months and 6 years of age; subsequently, about 3.6 % of the popul ation will suffer from an acute symptomatic seizure (excluding febrile events), whereas 3 % will be diagnosed at some point in life with epilepsy ( 3 \200\2235 ). A pre-hospital sett ing is frequently involved, as half of patients with seizures may arrive to the hospital by ambulance ( 6 ), and about 3 % of ambulance transports are due to seizures ( 7 ), again wi th higher proportions (up to 9 % ) among the pediatric population ( 8 , 9 ). aetiologies or comorbidities ( 2 ). After a \201 rst ever seizure, mortality is clearly h igher than in the standard population, principally owing to the underlying etiology, with p roportions around 14 \200\22318 % at 6 \200\22312 months ( 10 , 12 , 13 ). An American study estimated the median cost of an ED visit at 500 US$ in 2007; adding the a verage price of the ambulance ride (about 400 US$), the annual costs for emergency seizure care in the US may be set at around 700 million US$( 1 ). Facing the patient: differential diagnosis Seizure-mimicking entities are very varied ( 14 ). Persons presenting to the ED with a suspicion of seizures fall basically into two catego - ries: with or without loss of consciousness. In the latter setting, several other entitie s need to be ruled out at times. Migraine auras, which may mimic symptoms of partial seizur es, last by de \201 nition more than 4 minutes, as opposed to the epileptic \200\230march \200\231 that devel- ops over less than a couple of minutes. Movement disorders repre- sen t probably the most complex category from a semiological point of view ( 15 , 16 ). Focal o r segmental dystonias, especially if acute or paroxysmal, may be misdiagnosed as focal seiz ures; acute dystonias related to neuroleptic administration are usually con \201 ned to th e larynx, face, and eyes; in paroxysmal disorders, the history often unravels typical trigg ering factors, such as movements, fasting, or exercise. Choreatic movements are usually obv ious to an average experienced physician, but sometimes they may present unilaterally. Myoc lonus is typically irregular, and may be accentuated by posturing or tactile stimulation, b ut focal seizures may be virtually identical ( 17 ). Tics are recognized by their predictab le nature, and although they mostly represent a chronic condition, they may be enhanced by stress or metabolic disorders, as are abnormal startle reactions. Tremor related to Parkins onism or other disorders may be uni- or bilateral, but often change amplitude (or disappear ) after changing position. Clonus in the context of spasticity also disappears after a pass ive movement. Episodic ataxias are very rare, and their episodic nature (history taking!) l eads to the diagnosis. Finally, \200\234limb shak- ing \200\235 following transitory focal cerebrovascular involvement may also mimic focal seizures. Probably re \202 ecting underlying aetiologies, such as trauma and intoxications, males ar e about 1.5 times more prevalent than female subjects ( 2 , 10 ); African Americans are als o overrepresented as com- pared to Caucasians ( 2 ). Regarding age, an U-shaped curve is ob served: while the yearly incidence of acute symptomatic seizures per 100,000 population in all age groups is about 40, infants show an incidence of 250, patients above 75 an incidenc e of 120, while mid- dle-aged persons have an incidence of 15 \200\22340; this distribution is accounted for by febrile seizures or infections in children, and struc- tural brain dam age in elderly people ( 4 ). However, since the propor- tion of middle-aged persons in the population is higher than that of elderly, the absolute numbers are comparable across age s trata ( 10 ). While acute symptomatic seizures dominate the aetiological cat- egories, abou t half of patients presenting with seizures to the ED have had previous episodes ( 2 ). In adults, the most common causes are related to alcohol or illicit drug intoxications (especi ally in the middle-aged group), trauma (younger group), cerebrovascular diseases (elderly), and previous epilepsy, including antiepileptic drug (AED) withdrawal (across all ages) ( 2 , 10 ). Of note, it has been estimated that about 7 % of ED seizures may represent status epilepticus (de \201 ned using a 30-minute time window) ( 6 , 11 ). About one-fourth of se izure patients in the ED will be admitted to the hospital, especially if they are older and suffer from severe Facing a subject with continuing or resolved loss of consciousness, four main categories ne ed to be considered in the differentiation oxford textbook of epilepsy and epileptic seizures 338 Table 32.1 Differential diagnosis between epileptic seizures and syncope Table 32.2 Differential diagnosis between epileptic seizures and psychogenic non-epileptic seizure (PNES) Item Points Behavior PNES Epileptic seizures Lateral tongue bite + 2 Eyes Frequently closed Frequently open D j -vu sensation + 1 Weeping Possible Exceptional ( \200\230dacrystic seizures \200\231) Emotional stress + 1 Ictal movements Multiform, uncoordinated, waxing-waning Stereotyped, with clear start and stop Head turning during the spell + 1 Unresposive, or unusal posturing, or jerks during the spell + 1 Ictal stuttering and postictal whispering Possible Exceptional Postictal confusion + 1 Lightheadedness \210\222 2 Ictal hyperventilation Frequent Exceptional Sweating \210\222 2 Postictal cough, nose wiping Absent Possible (temporal lobe seizures) Prolonged sitting or standing \210\222 2 Postictal stertourous breathing Absent Possible (generalized convulsions) A score results after summing all the points. Score \211 1: the patient probably had an epileptic seizure; score <1: the patient probably had a syncope. Adapted from Sheldon et al. ( 22 ). Postictal rapid super \201 cial breathing Possible Absent from seizures: metabolic \200\223toxic disturbances, syncope, psychogenic events, and, more rarely, sleep-related behaviors. In this context, syncope is much more frequent than seizu res or other neuropsychi- atic disorders: in the ED, more than 70 % of patients with a hist ory of a transitory consciousness impairment fall into this broad cate- gory, as compared t o 15 % with an unexplained cause, and 10 % with a neurological or psychiatric origin ( 18 \200\22320 ). A careful history taking is, again, mandatory and greatly helps in the diagno sis. Syncope are typical preceded by symptoms of low brain blood per- fusion, such as light headedness, impaired vision with a uniform gray-black character, impaired audition (such as if the patient was wearing earplugs), sweating, and nausea. Falling may be accompa- nied b y a few uncoordinated jerks ( \200\234which are analogous to limb shaking \200\235, and who se duration may be overestimated by witnesses), and a by a pallor re \202 ecting the prese rved lung function and the impaired capillary perfusion. The duration is typically less tha n 30 \200\22360 seconds, and consciousness recovers rapidly, as soon as the body is in a re cumbent position, unless a brain trauma has occurred (history taking with witnesses, and sc alp inspection). At times, a minor anterior tongue bite may be observed, which is distinct from the often deep lateral scar seen after convulsive seizures ( 21 ). A potentially usefu l algorithm to differentiate seizures from synco- pes has been proposed ( 22 ) (Table 32. 1 ). Self injury Possible Possible Tongue bite Possible Possible (generalized convulsions) Incontinence Possible Possible Adapted from LaFrance ( 29 ) and Rossetti and Kaplan ( 31 ).