Ghai Essential Pediatrics8th

Table 17.37: Distinguishing features of type 1 and type 2 diabetes mellitus

recovers. These children and adolescents should be evaluated for hyperlipidemia, diabetic retinopathy and nephropathyatdiagnosis.Itis recommendedthatchildren at risk of type 2 diabetes be screened for diabetes.

Plasma Blood Sugar and Hemoglobin Goals

Goals need to be set, but nevertheless are individualized and planned. Blood sugar goals may need to be higher for children with hypoglycemic unawareness (see below) or who have frequent and serious hypoglycemia. Goals may be set lower if achievable without complication and risk. Youngerchildrenhave a higher risk ofhypoglycemia. Prepubertal children are at a lower risk for longterm complication than are postpubertal children. Therefore, goals for an acceptable range for blood sugars and for glycosylated hemoglobin can safely be set a little higher for younger children.

Table 17.38: Goals of blood sugar and glycated hemoglobin (HBA1c)

Toddlers and Preschoolers (0--6 yr)

Pre-meal glucose: 100-180 mg/dl

Bedtime and overnight glucose: 110-200 mg/dl HbAlc: <8.5%

School age (6-12 yr)

Pre-meal glucose: 90-180 mg/dl

Bedtime and overnight glucose: 100-180 mg/di HbAlc: <8.0%

Adolescents and young adult

Pre-meal glucose: 90-130 mg/dl

Bedtime and overnight glucose: 90-150 mg/dl

HbAlc: <7.5%

Endocrine and Metabolic Disorders -

The goals of blood sugar and glaycated hemoglobin recommended by the ADA are shown in Table 17.38.

Complications of Diabetes

Acute Complications

Diabetic ketoacidosis, a serious acute complication due to insulin deficiency is discussed below.

Hypoglycemia is defined as blood sugar less than 60 mg/ dl. Low blood sugar usually occurs when the child has been unusually active and insulin and/or food has not been adjusted for increase in activity. Counter-regulatory hormones, namely adrenaline, glucagon and cortisol, are secreted to correct the hypoglycemia. Adrenergic symp­ toms such as tremors, pallor, tachycardia and sweating can be seen. If left untreated, more severe symptoms may occur dut to neuroglycopenia (decreased availability of glucose to the brain), including seizures, fainting and coma. Prevention of hypoglycemia should be discussed with the patient and family during diabetes education sessions. Treatment follows a rule of 15, i.e. 15 g of free sugar are given in form of sugar, honey, juice or carbo­ nated drink, followed by recheck of blood sugar in 15 minutes. If the child is unconscious glucagon is adminis­ tered intramuscularly. The dose is dependent on the age and weight of the child as follows: infants 0.3 mg, child <25 kg, 0.5 mg and child >25 kg 1.0 mg. If glucagon is unavailable intravenous dextrose is given.

Intermediate Complications

Lipoatrophy is fat atrophy at the injection site. This can be prevented by rotation of injection sites.

Limited joint mobility is typically noted in the hands. This occurs due to flexion contractures of the metacarpo­ phalangeal and proximal interphalangeal joints.

Growthfailure occurs inchildrenwhose diabetes is not well controlled. Mauriac syndrome occurs with poor control of diabetes. These children have hepatomegaly, pale skin and extreme short stature.

Delay in sexual maturation is associated with inadequate control of diabetes and delayed bone age.

Hypoglycemic unawareness is caused by frequent hypo­ glycemia associated with tight metabolic control of dia­ betes. It is due to impaired counter regulatory response to hypoglycemia. Raisingblood sugar targets and preven­ tion of hypoglycemia usually causes reversal of hypo­ glycemic unawareness.

Chronic Complications

Retinopathy in diabetes is characterized by micro­ aneurysms and proliferative disease. Previously 80-90% of individuals developed eye disease by 15 yr of diabetes.

With intensive management of diabetes this complication is delayed to beyond childhood.

Ophthalmologic examination should be conducted once the child is 10 yr of age and has had diabetes for 3- 5 yr. Annual followup is suggested.

Peripheral neuropathy is unusual in children and adole­ scents. This results in decreased nerveconduction velocity and sensory changes. An abnormality in vibration perception may be the first finding.

Nephropathy It is defined by albuminuria in the urine and is preceded bymicroalbuminuria. It causes significant morbidity and mortality in adulthood. Annual screening of microalbuminuria is initiated once the child is 10 yr of age or has had diabetes for 5 yr. If screening shows an elevated ratio of spot urine microalbumin to creatinine, 24 hr urine microalbumin is estimated. Patients with elevated microalbumin to creatinine ratio should receive

ACE inhibitors to delay the progression of nephropathy. Dyslipidemia Fasting lipidprofileisperformedon allpre­

pubertalchildren>2 yrofageatthetimeofdiagnosis(after glucose control is achieved) if there is a family, history of elevatedcholesterol(>240 mg/dl)and/oracardiovascular event beforeage55 yr inthefamily. Iftherearenoconcerns of hyperlipidemia in the family, screening is performed afteronset ofpuberty(>12 yr). IfLDLis<100 mg/dl, alipid profile is repeatedevery5 yr. Forpubertal children(>12 yr ofage),afastinglipidprofileisperformedat diagnosisafter glucose control is achieved. If LDL is<100 mg/dl, lipid profile is checked in 5 yr. If lipids are abnormal, annual monitoring is recommended in both age groups. Intervention is needed if fasting LDL is >100 mg/dl once glucose control is established. Initial therapy is nutritional modification with decrease in saturated fat in diet. A pharmacologic agent is added forLDLof>160 mg/dl, and inpatientsatriskofcardiovasculardiseaseandLDLvalues 130-159 mg/dl after initiation of dietary changes and lifestyle intervention. The goal of therapy is LDL value of <100 mg/dl.

Celiac disease Evaluation of celiac disease involves testing for serum IgA, antigliadin antibodies and trans­ glutaminase antibodies. Further evaluation is suggested if these antibodies are elevated.

Specific Recommendations for Longterm Followup

Scheduled followup visits at 3 month intervals with dia­ betes team is recommended. At these visits the following is planned:

•Assessment of growth, weight and puberty

•Physicalexaminationwithspecificfocusonthyroid,injec­ tion sites, fw1dus, foot and neurological examination.

•Assessment of blood sugar records checked typically pre-meals and at bedtime. Periodic measurements should be advised at 2 AM and postprandially if blood

sugar range is inconsistent with glycated hemoglobin. Insulin adjustments are performed, if needed.

•Ongoing diabetes education is necessary, including prevention and management of hypoglycemia and discussion of sick day principles.

•Eyeexaminationis advisedannually, if initial eye exam was normal.

•Glycated hemoglobin is checked at 3 month intervals.

•Fasting serum lipids are evaluated annually, and more frequently if abnormal.

•Thyroid function tests are done yearly to assess for hypothyroidism, and more frequently if abnormal.

•Psychological assessment is conducted and referral to psychology advised, if necessary

•Urine microalbumin is assessed (normal 30-399 mg/ 24 hr).

•For a child receiving continuous subcutaneous insulin infusion): specific education is reviewed and pump function assessed. One should consider the need for continuous glucose monitoring devices.

•At each visit, one should assess nutrition, revisit nutritional planandadvise regardingphysical activity.

DiabeticKetoacidosis

Diabeticketoacidosis(DKA)isthemostseverecomplication of diabetes mellitus. It is a state of hyperglycemic dehy­ dration andketotic acidemia. It is characterized by hyper­ glycemia, acidosis and ketosis. Blood sugar is typically over 250 mg/di, ketonemia is present(ketones positive at greater than 1:2 dilution), serum pH is<7.3 and serum bicarbonate<15 mEq/1. In moderate DKA, serum pH is <7.2 and bicarbonate<10 mEq/1. Severe DKA is charac­ terized by serum pH< 7.1 and bicarbonate<5 mEq/1. It can occur in both type 1 and type 2 diabetes. Hyper­ glycemic hyperosmolar state is a hyperglycemicstateseen primarily in adolescents with type 2 diabetes. Both disorders are associated with absolute or relative insulin deficiency, volume depletion and acidosis.

DKA can occur as the initial presentation of type 1 diabetes; 15-70% of all newly diagnosed children present with DKA. The overall rate of DKA among pediatric patients has remained about25%. Theprevalence of DKA decreases from 36% in children<5 yr of age to 16% in those >14 yr. Mortality rates in children vary from 0.15- 0.3%; cerebral edema accounts for 60-90% of all DKA related deaths in children.

DKA most commonly occurs in children and adole­ scentswho are non compliant toinsulintherapy. Recently, it has also been seen in patients using insulin pumps due to acute interruption of insulin infusion due to pump malfunction. In young patients with type 1 diabetes, psychological problems complicated by eating disorders are a contributingfactorin20% ofrecurrentcases. Infection may be a precipitation factor.

Pathophysiology

The mostimportant factor that contributes to pathogenesis of OKA is insulin deficiency. This coupled with an increase in counter-regulatory hormones namely glucagon, growth hormone and cortisol augments glucose production from glycogenolysis and gluconeogenesis while limiting glucose utilization. These hormonal alterations result in hyperglycemia and lipolysis resulting in increased free fatty acid production. Oxidation of fatty acids in liver generate P-hydroxybutyrate and acetoacetic acid (ketones) which results in acidosis and ketosis. Hyperglycemia results in osmotic diuresis causing dehydration and hypovolemia and can progress to severe dehydration and shock. Dehydration also causes lactic acidosis which increases acidosis. Ketosis and acidosis results in electrolyte imbalance and other most diagnostic mani-fes­ tations of OKA including fruity odor and rapid respi­ rations (Kussmaul breathing). Acidosis causes shift of intracellular ions, most importantly potassium, and phosphate, to the extracellular compartment. These are lost in urine in excess amounts resulting in total body potassium and phosphate depletion. However, serum levels of potassium are variable, depending on the stage of OKA. Initially serum potassium levels are high, and once treatment with insulin is initiated the child becomes hypokalemic. Phosphate is a major component of 2, 3 DPG and its depletion results in decrease in 2, 3 DPG and reduced oxygen delivery to the tissues. Hypertriglyceri­ demia and hyperglycemia also falsely lower serum sodium resulting in pseudohyponatremia. Each 100 mg/ dl elevation in blood sugar lowers sodium by 1.6 mEq/ di.

Clinical Features

The symptoms and physical signs of OKA are listed in Table 17.39.

Though the metabolic derangements of OKA may take a long time to develop, the signs and symptoms develop in 24 hours. Nausea and vomiting are almost always present. Abdominal pain is usually severe and mistaken for acute appendicitis and other causes of severe abdominal pain are considered. Dehydration is usually severe. Hypotension and shock can be seen in severe OKA. Acidosis and acetone accumulation result in classic signs of OKA; with rapid

Endocrine and Metabolic Disorders -

respiration (Kussmaulbreathing)and fruity odor. Lethargy and cerebral depression may evolve into coma. Cerebral edema is a serious complication of OKA and is more frequently seen in children. Children may also have signs of infection, including fever, which precipitate OKA.

Laboratory Evaluation

Criteria for confirmation of diagnosis of OKA include blood glucose >250 mg/dl, blood pH <7.3 and serum bicarbonate <15 mEq/1. Serum potassium may be normal initially but declines with therapy. Serum sodium is low. An elevated creatinine usually reflects dehydration. Leukocytosis and hypertriglyceridemia are common. Serum ketones are elevated being positive even in 1:8 dilution. The levels of P-hydroxybutyrate are higher than acetoacetate, but the latter is preferentially detected by the nitroprusside strip test. Plasma assays of P-hydroxy­ butyrate more accurately reflect the true ketone levels.

Management

The goal of treatment is slow correction of dehydration and acidosis to prevent the development of cerebral edema.

A practical approach to the (fluid, electrolyte and IV insulin therapy) management of diabetes ketoacidosis is shown in Table 17.40.

Cerebral Edema

This is complications of OKA, is characterized by headache, bradycardia, altered neurological status and desaturation in an otherwise improving child. The condition most commonly occurs during the first 5-15 hr of therapy. The rate of fluid administration should be reduced. Either IV mannitol (0.25-1 g/kg) over 20 min) or hypertonic (3%) saline (5-10 ml/kg over 30 min) is given to reduce edema.

Nonketotic Hyperosmolar State

This condition is characterized by severe hyperglycemia (usually >600 mg/dl), hyperosmolality (>350 mOsm/kg), low plasma ketones (negative or positive at <1:2 dilution) and dehydration. Although usually seen as a complication of non-insulin dependent diabetes, it can occur in type I diabetes in children if insulin is present to prevent ketoacidosis, but is insufficient to control the blood sugar. The principles of treatment include judicious fluid replacement, regular insulin and fluid therapy.

Suggested Reading

American Diabetes Association position statement: Standards of medical care diabetes 2011. Diabetes Care 2011, 51:34

Dunge, DB, Sperling MA, Acerini CL, et al. ESPE/LWPES Consen­ sus statement on diabetic ketoacidosis in children and adolescents. Arch Dis Child 2004;89:188-94

International Society for Pediatric and Adolescent Diabetes. Clinical practice consenus guidelines. Pediatric Diabetes 2009;10:1-210

APPROACH TO NEUROLOGICAL DIAGNOSIS

History

An accurate and sequential clinical history and detailed neurological and developmental examination may provide more information than expensive investigations.

Onset of illness. The mode of onset gives clues about the etiology. Head trauma, vascular causes, acute demye­ linating encephalomyelitis (ADEM) and acute infections are sudden in onset. Subacute onset is characteristic of infections with organisms of low virulence and neurode­ generative processes. Meningococcal meningitis has a galloping course, whereas tuberculous meningitis maygo on for weeks. A relapsing and remittingcourse can occur in multiple sclerosis and Devic disease. A progressive course indicates degenerative and neoplastic disorders.

Developmental history. A sequential development history helps to define the time of onset and rather ailment. All the developmental milestones are delayed if the disease begins at or near the time of birth of the child. Milestones may regress with acquired insults or degenerative disease of the nervous system. Always ask for consanguinity and family history of neurological disorders.

Physical Examination

Inspection is a crucial part of neurological examination. Observe posture, quality and symmetry of spontaneous movements, behavior, apathy, interest in surroundings, hyperkinesis, involuntary movements such as tremors, athetosis, chorea, myoclonus and convulsions.

Cranial nerves. Response to light stimuli and pupillary reflexes showintegrityofsecond and thirdcranialnerves. Ophthalmoplegiaandparalyticsquintindicateinvolvement of third cranial nerve. Down and out movement of the affected eye indicates fourth cranial nerve involvement. Fifth nerve integrity can be checked by conjunctiva! or corneal reflex. Sixth nerve paralysis, diagnosed by a

Veena Kalra

convergentparalytic squint, may bea false localizing sign. Facial asymmetry, loss of nasolabial fold on the ipsilateral side, pulling of the angle of the mouth on contralateral side and drooling of saliva indicates paralysis of seventh nerve. The integrity of cochlear division of eighth nerve is checked by auditory tracking. Ninth and tenth nerve integrity is determined by gag reflex and palatal movements. If the child can shrug his shoulders and turn his neck from side to side, eleventh nerve (accessory) is intact. In twelfth nerve palsy, the tip of the tongue is deviated to the side of the lesion.

Motor Examination

Best power in all limbs during spontaneous movement should be recorded in infants and toddlers. Detailed assessment of power should be attempted in older children. Assessment of tone helps in the localization of lesion.

Deep tendon reflexes. These are best elicited when the concerned muscle groups are relaxed. Exaggerated deep tendon reflexes imply upper motor neuron lesions and diminished reflexes are observed in lower motor neuron disease. Cerebellar lesions cause pendular knee jerks.

Developmental Examination

In infancy, tone, posture, neonatal reflexes, appearance of postural reactions are to be assessed. In addition, gross and fine motor functions, socioadaptive and language evaluation should be done using standard tests or charts of development. Hearing and vision evaluation is also mandatory.

Lumbar Puncture

Lumbar puncture is indicated in inflammatory CNS disorders, neonatal sepsis, malignancies (to determine CNS spread and for therapy), autoimmune diseases, demyelinating illnesses, slow virus infections specially

subacute sclerosing panencephalitis (SSPE), and for lactate, neurotransmitters and glycine in neurometabolic and neurotransmitter disorders. Lumbar puncture is not indicated infebrile convulsions except in infants to exclude meningoencephalitis. Lumbarpuncturehasbothdiagnostic and therapeutic utility in pseudotumor cerebri.

Fundusmustbeexamined prior toproceduretoexclude papilledema,assuddenreleaseofcerebrospinalfluid pres­ sure following lumbar puncture may result in medullary coning and cardiorespiratory arrest. Aseptic precautions should be maintained while doing lumbar puncture. Cerebrospinal fluid(CSP) opening pressure evaluation is useful.

CSF is examined for its color; microscopy for number and type of cells. Protein, sugar/chloride estimation is routinely performed. Blood sugar estimation should be performed at time of lumbar puncture for comparison. Culture, serology and newer diagnostic tests for antigen/ antibody detection should be done if infection is suspected.

Electroencephalogram (EEG)

Electroencephalogram is a commonly employed test. Electrical activityis recorded byplacing asetofelectrodes on the scalp in a specific arrangement. Recorded rhythms are evaluated bytheir rate(Hz), amplitude(µV), symme­ try, synchrony and morphology. The various rhythms include betarhythm at 14-20 Hz(cycles/sec), alpha rhy­ thm at 8-13 Hz, theta rhythm at 4-7 Hz and delta at 1-3Hz.Activity faster than betacanbeanartifactfromthe scalp muscles. Figure 18.1 depicts a normal EEG record.

Indications. EEG is useful in classifying, supporting and confirming diagnosis ofepilepsy and epilepsysyndromes. It distinguishes between seizure and nonseizure states, e.g. fainting spells, hypoxic episodes and breath holding spells. EEG is especially helpful for diagnosis of absence attacks, myoclonic epilepsies, nonconvulsive status, epilepsy syndromes, SSPE and herpes encephalitis. EEG is not indicated in typical febrile convulsions.

Abnormalities. The common abnormalities of background

Fig. 18.1: Normal EEG, in a 5-yr-old child. Note normal posterior dominant alpha background activity

may be generalized, localized or lateralized to one side and thus help to localize anatomic lesions. In addition, spikes, sharp waves, polyspikes or hypsarrhythmia may beseenin certainepilepsysyndromes/epilepsies(Fig. 18.2).

Fig. 18.2: Abnormal EEG, in a 4-month-old, showing abnormal slow chaotic background with multifocal spikes suggestive of hypsarr­ hythmia

Spikes are transient discharges that stand out from background, last less than 70 milliseconds and often accompanied by a slow wave. When spikes occur very closely, they are called polyspikes. Sharp waves have a duration of 70-200 milliseconds and are less pointed. A three per second spike and wave discharge is observed in typical absence attacks (Fig. 18.3). Brief bursts of polyspikesare common inmyoclonic epilepsies. In benign focal epilepsies of childhood, clusters of high amplitude, spike wave complexes are seen in rolandic areas. High voltage (>100 µV), generalized, chaotic slow waves (hypsarrhythmia) and multifocal spikes are common in infantile spasms.

Subacute sclerosing panencephalitis(SSPE) is charac­ terized by periodic epileptiform discharges recurring at similar intervals throughout the record. The discharges are similar in morphology and amplitude and often superimposable(Fig. 18.4).

Herpes encephalitis may be associated with periodic lateralized slow waves or high voltage complexes. Focal

Fig. 18.3: Synchronous 3 Hz spike wave discharges in a child with absence epilepsy

Fig. 18.4: High amplitude periodic sharp waves in a child with subacute sclerosing panencephalitis (SSPE)

slowing may be observed in inflammatory granulomas, cerebral abscesses and infarction. Generalized slowing of the background may be seen in encephalitic syndromes. Barbiturates and benzodiazepines produce generalized fast beta activity.

Limitations ofEEG. Two percent of the normal population may have abnormal EEG records with spikes that have no clinical consequence or diagnostic utility. Patients with epilepsies may have normal interictal records. Treatment should not be based on EEG alone; correlation with the clinical condition is important. EEG is not essential for decision to stop antiepileptic drugs in epilepsy, though it may be useful in predicting the risk of recurrence after discontinuation of anticonvulsants.

Video EEG and EEG telemetry are useful in identifying surgicalfoci of epilepsy andin management of intractable epilepsies.Magnetoencephalographyrecordsthemagnetic field generated instead of electrical potentials and can localize the focus three dimensionally.

Evoked Potential Response

Evoked potentials in response to visual, brainstem, auditory or somatosensory stimuli are useful tools to assess conduction, processing of informationandintegrity of specific sensory pathways. It also helps to determine the site of pathology. Brainstem auditory evoked potentials (BAEP) and otoacoustic emissions (OAE) can detect early defects ofhearing andpostkernicteric damage to the newborn. Visual evoked responses (VER) are useful to determine site and severity of neurological visual loss. These tools have diagnostic utility in deeply comatose patients and neurodegenerative disorders.

Electromyography

The technique of electrical recording from the muscle is called electromyography (EMG). Concentric needle electrodes are inserted into the muscle to be studied. Normally therestingmuscleis electricallysilent. Insertion

Central Nervous System -

of electrode causes a brief burst of electrical potentials called insertional activity. When the muscle contracts, the motor unit action potential is recorded. This is a triphasic record, which usually ranges from 200 to 500 µV with duration of 2-15 min.

Abnormal spontaneous activity suchasfasciculationsor fibrillations indicate denervation, e.g. spinal muscular atrophy. Largeamplitude,polyphasicandprolongeddura­ tion potentials may be seen in neurogenic abnormalities. In myopathies, theseunitsareoflowvoltage,shorterduration with early recruitment. Myasthenic syndromes reveal a decrementalresponse onrepetitive nerve stimulation test. When requisitioning an EMG, a partly involved muscle should be sampled rather than an atrophic or a normal muscle.

EMGisespeciallyhelpfultodistinguishbetweenneuro­ genic and myogenic weakness in a floppy infant.

Nerve Conduction Study

Nerve conduction studies are useful for diagnosing speci­ fic nerve lesions, neuropathies and in systemic disorders which alter motor and sensory nerve function. Diminished nerve conduction velocities, which imply diseases of myelin, canbe observed inpatientswithperipheral neuro­ pathies and dysmyelinopathies. Nerve conduction studies are useful in distinguishing polio-myelitis from Guillain­ Barre syndrome.

Neuroimaging

Ultrasonography is an investigation of choice in newborns and infants with a neurological illness through open anterior fontanel. It can be performed at bedside and providesquick andusefulinformation. Theventricles, part of cortex and periventricular tissue are very well visuali­ zed with ultrasonography. The peripheral cortex and posterior fossa is poorly visualized. A color Doppler ultrasound evaluates many vascular malformations and congenital anomalies in a two-dimensional way.

Computerized tomography (CT scan) The cross­ sectional images are computed into two mm sections of the brain. Newer modificationsandsophisticated scanners provide 3-D images, volumetric data and quick sequential images. CT evaluates anatomy of supratentorial brain structures reasonably well. Myelination, posterior fossa and brain stem structures are not well visualized. Calci­ fication is best evaluated by CT images (Fig. 18.5).

Indications. (i) Hypoxicischemic encephalopathy; (ii) head injury; (iii) craniofacial anomalies; (iv) inflammatory dis­ orders: CNS tuberculosis, neurocysticercosis, pyogenic abscesses and other inflammatory lesions; (v) suspected space occupying lesions; (vi) vascular causes-infarcts, sinus thrombosis, malformations; (vii) degenerative brain disorders; (viii) hydrocephalus, porencephaly and struc­ tural malformations.

Fig. 18.5: Noncontrast enhanced CT of brain showing a calcified cyst (Courtesy Dr. Atin Kumar, Deptt. of Radiodiagnosis, AIIMS)

CT is not very useful in a large proportion of neuro­ metabolic, neuromigration and genetic disorders. In vascular, inflammatory, infectious or neoplastic lesions a plain scan followed by contrast enhanced scan improves diagnostic yield.

Magnetic resonance imaging (MRI) MRI provides

anatomical delineation, gray-white matter distinction, detection of myelination, congenital abnormalities, vascular anomalies and migration defects withfar greater diagnosticdetailthanCT. Themidlinestructures, posterior fossa and brainstem structures can be visualized well. Sagittal and coronal views permit volume evaluation of CNSstructures. Somedegenerative disorderscanbepicked up early by MRI. MRI is also of particular use in patients with intractable epilepsy as it helps in anatomic locali­ zation of lesion. Newer MR techniques-MRspectroscopy that identifies metabolites like NAA, choline, lactate in specific voxels of the brain is useful for diagnosis of meta­ bolic disorders, cystic lesions and tumors and is being increasingly used as an investigative tool.

Functional scans Functional scans like positron emission tomography (PET) help to demonstrate perfusion, oxygen andglucoseuptakeindifferentpartsofbrainlikecerebrum, cerebellum, thalamus and basal ganglia. These scans have utility in identifying surgically resectable intractable epi­ lepsies, cerebraltumors and head injuries. PET scans can bemodifiedtoassesscerebralbloodvolume,cerebralblood flow,oxygenandcerebralglucosemetabolism. Thesehave been used as research tools for assessing brain develop­ ment, speech and vision dysfunction. PET is extremely useful for localization of an anatomic focus in presurgical work up of intractable epilepsy.

SPECTscans utilizing hexamethyl-propyleneamine oxime (HMPAO) and ethyl cysteinate dimer (ECD) are widely available. They are useful toidentifyperfusioninictal and interictal states, and are important presurgical investi­ gations of intractable epilepsies.

Others

Digital subtraction cerebral angiography is done to evaluate cerebrovascular disorders. Carotid Doppler studies can be usedtostudyflowpatterns.Myelographyisusedforinvesti­ gating compression of the spinal cord. Metrizamide myelogram can be performed to evaluate compressive myelopathies on the CT scan. Biopsy of the brain may be indicatedformalignantordegenerativedisorders. Psycho­ metric tests are carried out for measuring cognitive ability and intelligence of patients with suspected mental retar­ dation.

SEIZURES

Seizures (convulsions, fits) are caused by abnormal electrical discharges from the brain resulting in abnormal involuntary, paroxysmal, motor, sensory, autonomic or sensorial activity. About 5 percent children experience convulsions duringthefirst fiveyearsoflife.Motormove­ ments consisting of tonic and clonic components are the most commonly observed phenomenon, except in the newborn period.

Several times, a child may present with a condition that can mimic or be misinterpreted as a seizure. These conditions include convulsive syncope with or without cardiac dysarrhythmia, decerebrate posturing, psycho­ genic events, dystonia and migraine. Seizures should be differentiated from these conditions as misdiagnosis can have significant therapeutic implications.

Neonatal seizures oftenpresent with twitching of the limbs, fluttering of the eyelids, sucking movements and conju­ gate deviation of the eyes. These should be distinguished from jitteriness, tremors, startle response to stimuli, sudden jerks on awakening and tremulousness of the hungry child.

Common causes of convulsions are better classified according to the age at onset (Table 18.1).

Approach to a Child wthi Convulsonsi

Agood description oftheseizuresincludingmode ofonset, details of aura, type of seizure, automatism, associated behavioral abnormalities and the postictal phase shouldbe obtained. An accurate seizure description is more informative than detailed neurological examination or investigations. Perinatal, developmental, andfamilyhistory of seizures help in determining the cause. The childshould be examined for evidence of raised intracranial tension, degenerative, metabolic or congenital disorders.

Table 18.1: Causes of convulsions Early neonatal period (0-7 days)

Birth asphyxia, difficult obstructed labor Intraventricular, intracerebral hemorrhage Pyridoxine dependency, hypoglycemia, hypocalcemia Inborn errors of metabolism

Maternal withdrawal of medications

Injection of local anesthetic into the fetal scalp during the paracervical block given to the mother

Neonatal period (7-30 days)

Transient metabolic: Hypocalcemia, hypomagnesemia, hypoglycemia, dyselectrolytemia

Developmental malformations

Infections: Meningitis, septicemia, tetanus neonatorum, intrauterine infections

Metabolic errors: Phenylketonuria, maple syrup urine disease, galactosemia, urea cycle disorders

Beyond neonatal period

Simple febrile convulsions Epilepsy syndromes

Infections: Bacterial meningitis, intrauterine infections, tuberculous meningitis, aseptic meningitis, encephalitis, cerebralmalaria, Reye syndrome

Metabolic causes: Dyselectrolytemia, hypocalcemia, hypo­ magnesemia, inborn errors of metabolism

Space occupying lesions: Neoplasm, brain abscess, tuberculoma, cysticercosis

Vascular: AV malformations, intracranial thrombosis, hemorrhage

Miscellaneous: Hypertensive encephalopathy, sequelae of birth trauma and birth asphyxia, gray matter degeneration, storage disorders

Drugs, poisons: Phenothiazines, salicylates, phenytoin, strychnine, carbon monoxide, lead

Role of Investigations

Estimation of glucose, calcium and screening tests for neurometaboliccausesusuallysuffice. Detailedmetabolic studies, including screening of amino acids, blood ammonia, blood and CSF lactate/pyruvate levels are indicatedifinbornerrors ofmetabolismaresuspected and in familial seizures.

Electroencephalography (EEG). It is the best supplementary test for classification and diagnosis of epilepsy. It should be used to support the diagnosis of seizure, diagnose certainepilepsysyndromes, localizeanepilepticfocusand determine itsanatomicalbasis. EEG does not always help in determining the duration of therapy. Focal EEG abnor­ malities justify the need for imaging.

Cranial imaging. X-ray films of the skull are not helpful, except in microcephaly, scattered calcification, suture evaluation and thickening of the calvarium. MR imaging, CT scans and functional imaging are indicated in partial

Central Nervous System -

seizures, seizures with focal neurological deficits, dysmorphicfeatures,orskin lesionssuggestingneuroecto­ dermatoses and in the presence of raised intracranial pressure.

STATUS EPILEPTICUS

Status epilepticus (SE) implies prolonged single seizure or multiple episodes of seizures lasting more than 30 min without regaining consciousness in between. Impending status epilepticus refers to any seizure lasting more than 5 min.

SE can be classified as convulsive (tonic-clonic, clonic, tonic, or myoclonic) or nonconvulsive (absence, non convulsive, speech sensorial alteration). Convulsive SE is the most common and is associated with significant morbidity and mortality. The neurological sequelae following SE depend upon etiology, age and duration of SE.Therisk of complications increases substantially with duration (>60 min). Neurologicalresidua include mental retardation, focal neurological deficits, behavioral disorders and chronic epilepsy. Seizures recur in 25-75% of patients. The mortality rate is 10%; most deaths are attributable to the patient's underlying pathology.

In over 50% of cases, SE is the patient's first seizure. About 3% of epileptics experience a SE in their lifetime. Approximately 25% of childhood SE is idiopathic, 25% is associated with fever or meningoencephalitis, while 50% of patients have neurodevelopmental abnormality, head trauma, stroke, drug intoxication, subarachnoid bleed, pyridoxine deficiency or metabolic abnormality (hypo­ glycemia, hyponatremia).

Pathophysiology

SE results from excessive and persistent excitation, or ineffective recruitment of inhibition. Excitatory neuro­ transmitters include glutamate, aspartate and acetyl­ choline and the dominant inhibitory neurotransmitter is gamma-aminobutyric acid. The blockage of N-methyl-D­ aspartate (NMDA) channels by magnesium ions seems to be important in the pathogenesis of neuronal damage in SE. Associated hypoxia, hypotension, acidosis and hyperpyrexia exacerbate the neuronal damage.

Evaluation in the Emergency Department

History is taken for description of the event, associated symptoms,durationandthepostictalperiod,priorhistory of seizures, noncompliance with antiepileptic drugs (AEDs) orchangeofAEDand history ofpriorneurological development.

If postictal confusion does not resolve search for other causes, e.g. hypoglycemia, dyselectrolytemia, CNS infection, CNS vascular event, drug toxicity, psychiatric disorders and nonconvulsive status epilepticus (SE). Nonconvulsive SE can be diagnosed by EEG monitoring.

Investigations

Patients who are in convulsive SE require comprehensive diagnostic testing which includes serum glucose, electro­ lyte, urea, creatinine, calcium, magnesium (if indicated), complete blood cell count, malarial parasite and culture (if fever), arterial blood gas analysis, determination of anticonvulsant level (if on anticonvulsants), renal and liver function tests. Lumbar puncture is essential in suspected CNS infections. If meningitis is suspected but lumbar puncture cannot be performed, antibiotics should be administered immediately.

Neuroimaging. It is an important investigation. The yield varies from 3 to 41%, may be higher in developing coun­ tries because of neuroinfections and neurocysticercosis. A head CT is informative for acute head trauma, malig­ nancy, meningoencephalitis, neurometabolic disorders, persistent headache or in presence of focal neurological signs.

Electroencephalography (EEG). An urgent EEG is recom­ mended for patients with SE especially if nonconvulsive SE is suspected.

Management

There are four goals of therapy: (i) ensure adequate vitals, systemic and cerebral oxygenation, (ii) terminate seizure activity, (iii) prevent seizure recurrence, and (iv) establish the diagnosis and treat the underlying disorder.

Emergency Supportive Treatment

Secure the airway, maintain oxygenation, ensure per­ fusion, obtain intravenous access and protect the patient from hypoglycemia, hyperthermia and injury. Head and

neck should be positioned to keep the airway open. If necessary, airway should be suctioned. Oxygen by nasal cannula or mask, if needed, is administered, endotracheal intubation may be required. Two IV access should be established. Blood samples should be sent for laboratory studies, and 10-25% dextrose (2 ml/kg) should be given empirically. Systolic BP should be maintained at normal levels. Hyperthermia occurs frequently in SE; temperature should be recorded and treated promptly.

Anticonvulsant Treatment

The goal of treatment is rapid termination of clinical and electrical seizure activity by the prompt administration of appropriate drugs in adequate doses, with attention to the possibility of complicating apnea, hypoventilation and other metabolic abnormalities. The dosage schedule, route and rate of administration of the common anticonvulsant drugs used to treat acute seizures and SE are outlined in Tables 18.2 and 18.3.

Early and effective treatment is essential to prevent a refractory status and longterm neurological sequelae. Every institution should have a well-established treatment protocol depending upon the local availability of drugs. A proposed management protocol is shown in Fig. 18.6.

Domiciliary treatment Prehospital treatment with anticonvulsants is advocated for all children with recur­ rent prolonged seizures to reduce hospitalization episodes and complications. Drugs used are oral or intranasal midazolam or rectal diazepam.

Hospital treatment Any child who presents actively con­ vulsing to emergency room is assumed to be in SE and managed aggressively. The drug recommended is IV