Exploring Nelson with Vasu : CNS 3

It is a series of blog-post, for asynchronous learning written by Dr Vasu Burli which are actually his handpicked notes he derived from Nelson Textbook of Pediatrics. The notes are divided system-wise. The third in this series is ready to go online! Series 1: CNS Questions 1. Stroke 2. Viral meningoencephalitis

About Dr Vasu Burli Budding intensivist, currently persuing Pediatric critical care fellowship from Apollo Chennai, did his DNB in Pediatrics from renowned institute Kanchi Kama -Koti CHILD’S trust Hospital, Chennai. His area of interest are pediatric Intensive care and Emergency medicine.

1. Stroke
Stroke has emerged as an important cause of acquired brain injury in newborns and children.

Types

Ischemic: arterial ischemic stroke (AIS) cerebral sinovenous thrombosis (CSVT)

Hemorrhagic: hemorrhagic stroke and cerebrovascular disease.

Causes for arterial ischemic stroke:

Arterio-pathic Focal cerebral arteriopathy Transient cerebral arteriopathy Moyamoya Arterial infection migrane

Cardiac Complex cyanotic heart disease Cardiac procedures Arrhythmias Endocarditis cardiomyopathy

Genetic Hereditary dyslipoproteinemia Heritable disorders of connective tissue Organic acidemias Mitochondrial encepahalomyoapthies

Haematological Sickle cell anemia Iron deficiency anemia Inherited prothrombotic (factor V Leiden, prothrombin gene mutation) Acquired prothrombotic (e.g., protein C/S deficiency, antithrombin III deficiency, lipoprotein [a], antiphospholipid antibodies, oral contraceptives, pregnancy)

Causes of hemorrhagic stroke  

Vascular disorders Arteriovenous malforma tions Cavernous malformations (cavernomas) Venous angiomas Hereditary hemorrhagic telangiectasia Intracranial aneurysm Choroid plexus angiomas Drugs/ toxins

Blood disorder Idiopathic thrombocytopenic purpura Hemolytic uremic syndrome Hepatic disease/failure coagulopathy Vitamin K deficiency (hemorrhagic disease of the newborn) Disseminated intravascular coagulation

Trauma Middle meningeal artery injury Bridging vein injury (subdural hematoma) Subarachnoid hemorrhage Hemorrhagic contusions (coup and contrecoup) Non accidental trauma Iatrogenic (neurosurgical procedures, angiography)

 Clinical Featers

Clinical features:	Arterial ischemic stroke (AIS) The acute onset of a focal neurologic deficit in a child is stroke until proven otherwise. The most common focal presentation is hemiparesis but acute visual, speech, sensory, or balance deficits also occur. Children with these presentations require urgent neuroimaging and consultation with a child neurologist as emergency interventions may be indicated.	Hemorrhagic stroke (HS) Clinical presentations vary according to location, cause, and rate of bleeding. Acute hemorrhages may feature instantaneous or thunderclap headache, loss of consciousness, and nuchal rigidity focal neurologic deficits and seizures. HS can be rapidly fatal. In bleeds associated with vascular malformations, pulsatile tinnitus, cranial bruit and high-output heart failure may be present.
Investigations	CT imaging can demonstrate larger mature AIS and exclude hemorrhage. MRI identifies early and small infarcts and is therefore required to exclude ischemic stroke. Diffusion weighted MRI (DWI) can demonstrate AIS within minutes of onset. MR angiography can confirm vascular occlusion	lumbar puncture may be required to exclude subarachnoid hemorrhage. CT is highly sensitive to acute HS. MRI is highly sensitive to even small amounts of acute hemorrhage. Angiography by CT, MR, or conventional means is often required to exclude underlying vascular abnormalities.
Treatment	1.antithrombotic statergies- heparin, aspirin 2. neuroprotective statergies  Control of seizures, blood glucose and temperature. 3. disease specific Transfusion in sickle cell and iron def  anemia Immunosupression – vasculitis Surgery in moyamoya 4. Sec stroke prevention 5. Rehabilitation	The same principles of neuroprotection as in AIS. Reversal of anticoagulant therapy may be required (e.g., vitamin K, fresh frozen plasma) but the role of factor VII are unstudied. Emergent neurosurgical intervention for large or rapidly expanding lesions.

Neuroimaging findings:

      CT: hyperdense region surrounded by edema, intraventicular hemorrhages

      CT Venography: filling defects

      MRI: Focal increased diffusion, multifocal and restricted diffusion. Demyelination. Follow up MRI may show atrophy/ gliosis.

      MR Angiogram: occlusion, stenosis, decreased flow, puffed smoke appearance

 (moya moya), aneurysms, vascular malformations

      MR Spectroscopy: increased lactate in MELAS

      Gradient ECHO: can show presence of blood products

Differential diagnosis of stroke like disorders in children

DISORDER	CLINICAL DISTINCTION FROM STROKE	IMAGING DISTINCTION FROM STROKE
Migraine	Evolving or “marching” symptoms, short duration, complete resolution, headache, personal or family history of migraine	Typically normal Migrainous infarction is rare
Seizure	Positive symptoms, Todd paralysis is postseizure and limited	Normal or may identify source of seizures (e.g., malformation, old injury)
Infection	Fever, encephalopathy, gradual onset, meningismus	Normal or signs of encephalitis/cerebritis, which are typically diffuse and bilateral
Demyelination	Gradual onset, multifocal symptoms, encephalopathy Accompanying optic neuritis	Multifocal lesions, typical appearance (e.g., patchy in ADEM, ovoid in MS),
Hypoglycemia	Risk factor (e.g., insulin therapy), related to meals, additional systemic symptoms	Bilateral, symmetric Posterior dominant pattern
Watershed infarction due to global HIE	Risk factor (e.g., hypotension, sepsis, heart disease), bilateral deficits	Bilateral, symmetric restricted diffusion in border zones between major arteries (watersheds)
Hypertensive encephalopathy (PRES)	Documented hypertension, bilateral visual symptoms, encephalopathy	Posterior dominant, bilateral, patchy lesions involving gray and white matter
Inborn errors of metabolism	Pre-existing delays/regression, multisystem disease, abnormal biochemical profiles	MR spectroscopy changes (e.g., high lactate in MELAS)
Vestibulopathy	Symptoms limited to vertigo, imbalance (i.e., no weakness) Gradual onset	Normal
Acute cerebellar ataxia	Sudden onset bilaterally symmetric ataxia postviral	Normal
Channelopathy	Syndromic cluster of symptoms not localizing to single lesion Gradual onset, progressive evolution	Normal
Alternating hemiplegia	History contralateral events Choreoathetosis/dystonia	Normal

ADEM, acute disseminated encephalomyelitis; HIE, hypoxic-ischemic encephalopathy; MELAS, mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes; MR, magnetic resonance; MS, multiple sclerosis; PRES, posterior reversible leukoencephalopathy syndrome. MIS W HAD A/C  HIV (mis world had acute on chronic hiv) migrane, infections, seizure, watershed infarcts due to HIE, hypoglycemia, ataxia, demyelination, alternating hemiplegia, channelopathies, HTN, IEM, vestibulopathy.

2. Viral meningoencepahalitis

Viral meningoencephalitis is an acute inflammatory process involving the meninges and, to a variable degree, brain tissue.

Etiology:

Enteroviruses are the most common cause of viral meningoencephalitis.

Arboviruses are arthropod-borne agents, responsible for some cases of meningoencephalitis during summer months.

Several members of the herpes family of viruses can cause meningoencephalitis. (HSV-1) (HSV-2) (VZV) (CMV) (EBV) (HHV-6).

Other viruses – mumps and occasionally by respiratory viruses (adenovirus, influenza virus, parainfluenza virus), rubeola, rubella, or rabies.

Pathogenesis and pathology:

Neurologic damage is caused by direct invasion and destruction of neural tissues by actively multiplying viruses or by a host reaction to viral antigens.

Temporal lobe - HSV

Entire brain – Arbovirus

Basal structures - Rabies

Clinical features:

Fever, nausea and vomiting, photophobia, and pain in the neck, back, and legs are common. The presenting manifestations in older children are headache and hyperesthesia, and in infants, irritability and lethargy. 

Headache is most often frontal or generalized; adolescents frequently complain of retrobulbar pain. As body temperature increases, there may be mental dullness, progressing to stupor in combination with bizarre movements and convulsions. Exanthems often precede or accompany the CNS signs.

Investigations: 
  

The diagnosis of viral encephalitis is usually made on the basis of the clinical presentation of nonspecific prodrome followed by progressive CNS symptoms. The diagnosis is supported by examination of the CSF, which usually shows a mild mononuclear predominance. EEG typically shows diffuse slow-wave activity, usually without focal changes. Neuroimaging studies (CT or MRI) may show swelling of the brain parenchyma. Isolation of the virus from the CSF. PCR for entero and HSV.

Treatment:    
  

With the exception of the use of acyclovir for HSV encephalitis, treatment of viral meningoencephalitis is supportive. Treatment of mild disease may require only symptomatic relief. More severe disease may require hospitalization and intensive care. If cerebral edema or seizures become evident, vigorous treatment should be instituted.

Prevention:

1. Widespread use of effective viral vaccines for polio, measles, mumps, rubella, and varicella.

2. The availability of domestic animal vaccine programs against rabies has reduced the frequency of rabies encephalitis.

3. Control of encephalitis due to arboviruses has been less successful because specific vaccines for the arboviral diseases are not available.

4. Control of insect vectors by suitable spraying methods and eradication of insect breeding sites.

5. Furthermore, minimizing mosquito bites through the application of DEET-containing insect repellents on exposed skin and wearing long-sleeved shirts, long pants, and socks when outdoors, especially at dawn and dusk, reduces the risk of arboviral infection.