Книги по МРТ КТ на английском языке / Neurosurgery Fundamentals Agarval 1 ed 2019

18.1  Neurology

18.1.1  Dementia

Basics of Dementia

Dementia is defined by the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) as evidence of significant cognitive decline from a previous level of performance in one or more of the following cognitive domains1:

•Learning and memory

•Language

•Executive function

•Complex attention

•Perceptual motor skills

•Social cognition

These deficits must not be better explained by another mental disorder such as ­depression, which can present as “pseudodementia.”

It is important to distinguish dementia from simple delirium. Delirium is defined as an acutely disturbed state of mind that is characterized by restlessness, illusions, and incoherence of thought and speech. Electroencephalography (EEG) in delirium will typically show diffuse ­slowing, while EEG in dementia may be normal.

Basic Guidelines for Biopsy (CJD)

So-called rapidly progressive dementias may require brain biopsy for diagnosis. The most concerning are prion diseases such as Creutzfeldt–Jakob disease (CJD), variant CJD (vCJD), kuru, fatal familial insomnia, and Gerstmann- Sträussler-Scheinker disease.2

Biopsy guidelines are as follows:

•The biopsy should be large enough (at least 1 cm3).

•Itarea.should be taken from an affected

•Itmatter.should include gray and white

•All tools should be sterilized properly afterward.

18.1.2  Headache Basics

Headache can be divided into two classifications: primary and secondary. Primary headaches include migraine and tension headaches, while secondary headaches are caused by systemic illness, intracranial pathology, trauma, surgery, and lumbar puncture.

Headaches Requiring Investigation

Headaches that are new, sudden in onset, severe, different from patient’s usual headache, or headaches associated with an abnormal neurologic examination require further investigation with computed tomography (CT) or magnetic resonance imaging (MRI).

Migraine

Common Migraine

Migraine is defined as an episodic headache lasting several hours, typically unilateral and associated with either nausea, vomiting, photophobia, or phonophobia.3

Classic Migraine

Classic migraine is a common migraine plus an aura. Typically, migrainous auras consist of “positive” phenomena like flashing lights, kaleidoscope vision, and paresthesias which help to differentiate them from stroke-like symptoms.3

up from a reclined position and is relieved or resolved when patient is recumbent.

Pathophysiology

Cerebrospinal fluid (CSF) leak from unhealed dural openings can lead to persistent intracranial hypotension.

Cluster

Basics

These headaches, lasting typically 30 to 90 minutes, are characterized by severe, recurrent unilateral attacks of pain, usually around the V1 location with associated ­ipsilateral autonomic symptoms including conjunctival injection, nasal congestion, rhinorrhea, lacrimation, or facial flushing.4,​5

Treatment

•100% O2

•Sumatriptan subcutaneous (SQ)

•Steroids

•Refractory cases may be considered for the following:

◦Percutaneous radiofrequency sphenopalatine ganglion blockade

◦Hypothalamic deep brain stimulation

•May be treated prophylactically with verapamil

Post Puncture Headache

Basics

Also known as “spinal headache.” May occur after any procedure where the dura is punctured and may also occur idiopathically with spontaneous intracranial hypotension.4

Features

Headache is positional and worsens significantly when patient sits up or stands

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Neuroimaging

MRI may show diffuse pachymeningeal enhancement and T2 hyperintensity.

Treatment

•Lay flat for 24 hours

•Hydration, both oral (PO) and intravenous (IV)

•Tight abdominal binder

•Caffeine, PO or IV

•High-dose steroids

•Blood patch if above fails

18.1.3  Parkinsonism Classic Parkinson’s Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease. It affects 1% of the population older than 60 years, but it has several mimics which can make diagnosis difficult even for the experienced neurologist.

It is characterized by the following constellation of symptoms:

•Bradykinesia

•Rigidity

•Resting tremor

•Postural instability and gait impairments

Symptoms are due to a loss of dopaminergic neurons, mainly in the substantia nigra pars compacta. These neurons normally project to the caudate and putamen and modulate corticostriatal transmission, which is essential for normal movement.

The cause of degeneration is unknown, but there is buildup of α-synuclein pro- tein in these cells which can be seen microscopically.6

Other Types of Parkinson’s Disease Plus

Other types of parkinsonism, often referred to as “Parkinson’s disease plus (PD+)” can be seen. These disorders include progressive supranuclear palsy (PSP), multiple system atrophy (MSA), corticobasal degeneration (CBD), and dementia with Lewy bodies (DLB). All forms involve bradykinesia and rigidity but frequently have earlyonset of memory loss and disturbances in mentation. Parkinsonism can also be drug induced from antidopaminergic medications like antipsychotics and antiemetics. It can also be vascular, normal pressure hydrocephalus (NPH), or stroke-related. There are rare familial forms of parkinsonism as well.7

Surgical Treatment

Surgical options include placement of a deep brain stimulator (DBS) to unilateral or bilateral subthalamic nucleus (STN), or to the globus pallidus internus (GPi). GPi DBS may have fewer neuropsychiatric side effects.

Surgery has been shown to be superior to the best medical therapy for dyskinesia, but patient selection is very important.8

18.1.4  Essential Tremor

Thalamic DBS, targeting the ventral intermediate nucleus (VIM) markedly reduces the severity of essential tremor, even in those refractory to medication.9

18.1.5  Multiple Sclerosis Basics

Multiple sclerosis (MS) is a central nervous system (CNS) demyelinating disease affecting the brain, spinal cord, and cranial nerves. There is no peripheral nervous system (PNS) involvement.

Epidemiology

MS affects approximately 450,000 patients in the United States and 2.3 million worldwide. It is three times as common in women, and the usual age of onset is in young adulthood, but it does not have a major impact on life expectancy. The lifetime financial burden of MS is estimated at well over $1.2 million per person.10

Clinical

With the most common variant, relapsingremitting MS, patients experience short periods of acute inflammation and new disability in between longer periods of disease inactivity. Inflammation can occur anywhere in the CNS, but demyelinating plaques most commonly occur in the optic nerves, periventricular white matter, corpus callosum, juxtacortical U-fibers, and cerebellar peduncles.

A relapse consists of neurologic disturbance at least 24 hours in duration in the absence of fever or infection. Separate attacks should be divided by at least 30 days without symptoms.10,​11

Diagnostic Criteria

The most current criteria are the 2010 revised McDonald Diagnostic Criteria. Diagnosis requires elimination of more likely diagnoses. In order to diagnose MS, the lesions must be disseminated in time and space. Clinical evidence alone will

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suffice if there have been two or more separate attacks consistent with MS.

Dissemination in space consists of at least one T2 lesion in at least two out of four areas of the CNS:

•Periventricular

•Juxtacortical

•Infratentorial

•Spinal cord

Dissemination in time consists of a new T2 and/or gadolinium-enhancing lesion on repeat MRI or the presence of asymptomatic gadolinium-enhancing and nonenhancing lesions at any time.

Active demyelinating lesions will enhance with gadolinium, while old inactive lesions will be hyperintense on T2 and FLAIR without enhancement. The reason for enhancement is breakdown of the blood– brain barrier (BBB).10 CSF analysis can ­support the diagnosis. Positive CSF findings including oligoclonal immunoglobulin G (IgG) bands or elevated IgG index should be checked in all suspected MS cases if the diagnosis is not straightforward.

18.1.6  Motor Neuron Diseases

Amyotrophic Lateral Sclerosis

Epidemiology

In the United States, nearly 5,000 people per year are diagnosed with amyotrophic lateral sclerosis (ALS). Mean age of onset is 56 years. Male to female ratio is about 1.6:1. Patients typically die of respiratory failure and typically pass away around 3 years after diagnosis.12

Pathology

The most common genetic cause is a mutation of C9orf72 which causes a GGGGCC

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nucleotide repeat and accounts for up to 40% of familial cases. Mutations in the SOD1 gene account for 20% of familial ALS. Both upper and lower motor neurons are affected, including the giant Betz cells in the motor cortex, however, most sclerosis occurs in the lower motor neurons of the anterior horns.12

Clinical and Diagnosis

The El Escorial criteria were published in 1994 to outline the diagnosis of ALS. ALS is a clinical diagnosis that is characterized by predominantly lower motor neuron dysfunction including atrophy, fasciculations, and weakness. Upper motor neuron degeneration signs are also required to make the clinical diagnosis. Symptoms typically begin in one extremity and spread to other regions. The body is divided into four regions: bulbar, cervical, thoracic, and lumbosacral and the certainty of the diagnosis increases with the number of regions involved. A small portion of patients have “bulbar” onset with weakness of the swallowing muscles and dysarthria which carries a worse prognosis.12

Treatment and Prognosis

In adjunct with supportive care, riluzole, a drug which blocks the release of neuronal glutamate, and edaravone, a drug with an unknown mechanism of action but acts as a free radical scavenger, are the only currently Food and Drug Administration (FDA)-approved treatments for ALS. They have been shown to slow the decline of ALS.

Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is an autosomal recessive disease caused by loss of the SMN1 gene on chromosome 5q13.2. The carrier frequency in the United States is

1/50. There is now an FDA-approved intrathecal therapy, nusinersen, which is an antisense oligonucleotide that has demonstrated significant improvement in survival and motor milestone attainment.12

Treatment

Either IV immunoglobulin (IVIg) 400 mg/kg daily for 5 days or 1,000 mg/kg for 2 days or plasma exchange every other day for 10 days.

Spinal Bulbar Muscular Atrophy

Spinal bulbar muscular atrophy, or ­Kennedy’s disease, is an X-linked recessive genetic muscular atrophy caused by a CAG trinucleotide repeat in the androgen receptor gene on the X chromosome. Facial and oral fasciculations are the usual presenting symptoms followed by proximal muscle group atrophy in weakness.12

18.1.7  Guillain–Barre Clinical

Also known as acute inflammatory ­demyelinating polyneuropathy (AIDP), Guillain-Barre syndrome (GBS) is typically preceded by either a respiratory or gastrointestinal illness. It is thought to be triggered by a “molecular mimicry” response, with the immune system erroneously attacking host myelin and axons. Neurologic symptoms develop rapidly over several days typically with an ascending symmetrical paralysis. Low back pain is very common at the onset of GBS and may be the presenting symptom.13

Diagnostic Features

•Progressive,weakness relatively symmetric motor

•Areflexia

•Autonomic dysfunction: tachycardia, labile blood pressure

•CSF: albuminocytologic dissociation (increased protein without pleocytosis)

•Demyelination begins at the nerve roots

18.1.8  Myelitis

Transverse myelitis is a spinal cord disorder defined by any cause of inflammatory myelopathy, idiopathic or secondary to other neurologic or systemic conditions.

Etiology

Etiologies can be inflammatory, vascular, or compressive. Differential diagnosis includes MS, neuromyelitis optica, Sjögren syndrome, lupus-associated transverse myelitis, antiphospholipid antibody syndrome, copper deficiency, B12 deficiency, tertiary syphilis, sarcoidosis, and multiple separate viral/ bacterial illnesses, or even vaccinations.

Clinical Presentation

There is no clinical sign that can differentiate transverse myelitis from emergent compressive myelopathy, so all patients presenting with an acute myelopathy should be evaluated and treated emergently. Patients will present with sensory loss, back pain, weakness below the level of the lesion, ataxia, and bladder and bowel dysfunction. These symptoms can progress over hours, days or weeks. Reflexes can be diminished early on but eventually become hyperreflexic. A sensory level and urinary retention are highly suggestive of spinal cord disorder.14

Work-up

Imaging of the entire spinal cord should be strongly considered as even small cervical lesions can cause isolated lower extremity symptoms. MRI with and without contrast

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is the diagnostic modality of choice. CSF analysis in transverse myelitis will typically show a pleocytosis and elevated IgG.

Treatment

1 g/d of IV methylprednisolone. In severe cases where steroids are not effective, consider IV Ig 400 mg/kg/d for 5 days or plasma exchange every other day for five treatments.14

18.1.9  Neurosarcoidosis

Sarcoidosis is a disorder characterized by granulomatous inflammation of unidentified etiology able to affect all organ systems. The CNS is involved in fewer than 5% of cases although there are cases of pure CNS sarcoidosis without systemic involvement.15

Pathology

Definitive diagnosis requires histological proof of noncaseating granulomatous inflammation. This is a macrophage infiltration with epithelioid, nonnecrotic differentiation, multinucleated giant cells, with occasional lymphocytic or monocytic infiltration.16

Clinical Findings

For neurosarcoidosis, the most common presentation is that of a chronic meningitis, with headache, meningeal signs, and encephalopathy. Cranial nerve palsies, such as Bell’s palsy or ophthalmoplegia, are commonly seen as well, although any cranial nerve may be affected. The next most common presentation is myelopathy, followed by conus medullaris or cauda equina syndrome. These patients may also present with an asymmetric mononeuropathy multiplex picture.

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Laboratory

CSF shows a pleocytosis with a predominance of lymphocytes. Protein is commonly elevated, greater than 100. CSF glucose is low to normal. CSF angioten- sin-converting enzyme (ACE) levels carry a high false-positive rate and low sensitivity and are usually not useful.

Imaging

MRI of the entire neuraxis should be obtained with gadolinium. Common findings are T2 hyperintensity with gadolinium enhancement. Special attention should be paid to leptomeningeal enhancement and focal dural enhancement. There may also be enlargement of the pituitary stalk and focal parenchymal brain lesions. Different patterns of enhancement may be seen, such as uniform and mass-like, or irregular and linear. MRI of the spinal cord may show an interesting pattern of central canal and dorsal cord enhancement in a three-pronged “trident-head” shape. Chest X-ray or CT should be obtained to look for granulomatous inflammation and hilar lymphadenopathy.16

Biopsy

As mentioned before, definitive diagnosis of neurosarcoidosis requires tissue examination and the diagnosis guides treatment. Transbronchial lung biopsy may be the most straight­ forward approach if the lungs are involved, and skin biopsy is an option if there are dermal nodules. However, if primary neurosarcoidosis without systemic involvement is suspected, then CNS biopsy should be pursued.

Treatment

The mainstay of treatment is steroids coupled­ with steroid-sparing immunosuppressants.

Methotrexate, mycophenolate, tacrolimus, azathioprine, cyclophosphamide, and several others have been tried anecdotally. An objective measurement of improvement should be chosen beforehand, may it be imaging enhancement, neurologic deficit, or CSF pleocytosis.15,​16

18.1.10  Posterior Reversible Encephalopathy Syndrome

Clinical Features

Patients present with the signs or symptoms of a hypertensive encephalopathy, which include, but are not limited to, headache, nausea, vomiting, confusion, seizures, and visual changes with associated T2 hyperintense lesion in the white matter of the occipital white matter ( Fig. 18.1).17,​18

Fig. 18.1  Posterior reversible encephalopathy syndrome on MRI fluid attenuation inversion recovery sequence.

Imaging

MRI will show T2 hyperintensities in the white matter with little mass effect while CT scans looking at the same areas show reduced density in the corresponding areas. The changes on imaging are often located most prominently in the posterior part of the hemispheres.

Treatment

Treatments of posterior reversible encephalopathy syndrome (PRES) are limited with the most important being controlling the blood pressure, decreasing the peak blood pressure by about 20% or targeting a pressure of 150/100 is relatively safe.18

18.1.11  Vasculitis Introduction

Vasculitis refers to inflammation of the blood vessels and includes a variety of disorders in which the blood vessel wall inflammation leads to end-organ ischemic and inflammatory damage. They can be idiopathic, associated with immune complex deposition, chronic infections, or connective tissue diseases. Most have multisystem involvement, however, primary angiitis of the CNS and nonsystemic vasculitic neuropathy are pure CNS vasculitides. The vasculitides that may affect the CNS are as follows: polyarteritis nodosa, hypersensitivity vasculitis, giant cell arteritis (GCA), Takayasu’s arteritis, granulomatosis with polyangiitis, lymphomatoid granulomatosis, isolated angiitis of the CNS, and Behçet’s disease.19,​20

Giant Cell Arteritis

Epidemiology

Giant cell arteritis (GCA), also known as temporal arteritis, is a chronic granulomatous

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arteritis, which primarily affects the extracranial carotid arteries and may also affect other arteries and when there is involvement of the internal carotid artery, ischemic strokes can occur. GCA is seen in older patients, generally, older than 50 years. Up to 50% of patients have concomitant polymyalgia rheumatica.

Clinical

GCA typically presents with temporal headache, aching in proximal muscles, low-grade fever, weight loss, malaise, fatigue, and jaw claudication. Superficial temporal arteries can be tender to palpation with diminished pulsations present upon palpation. Visual loss can be transient, then progress to permanent visual loss via ischemic optic neuropathy.20,​21

Evaluation and Biopsy

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are often highly elevated; ESR is typically greater than 50 mm/h. Angiography can show stenotic lesions with associated inflammatory changes. Temporal artery biopsy is the gold standard for diagnosis of GCA and should be done on the side of involvement.20

Treatment

Prednisone 60 to 80 mg should be started. Treatment can be deescalated when ESR lowers.20

Other Vasculitides

Polyarteritis Nodosa

Polyarteritis nodosa (PNA) affects smalland medium-sized arteries with a predilection for branch points. It is a necrotizing vasculitis which eventually leads to thrombosis of the

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affected arteries. Presenting symptoms include headache, seizures, subarachnoid hemorrhage, retinal hemorrhages, and stroke. Treatment involves disease­-modifying treatments such as cyclophosphamide rather than chronic steroids.20

Wegener’s Granulomatosis

This affects the upper and lower respiratory tracts and the kidney. Myelperoxidase (MPO)/perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) are frequently present. Neurologic involvement includes focal cranial neuropathies, mononeuritis multiplex, and sensorimotor polyneuropathy. Treatment includes immunosuppressive agents like cyclophosphamide.20

Behçet’s Disease

Classic presentation is a triad of oral ulcers, genital ulcers, and uveitis. Pathophysiology involves perivascular lymphocytic infiltration of the veins, venules, capillaries with occasional arterial involve­ ment. Neurologic presentations include meningoencephalitis with headaches, encephalitis form with gradually evolving multifocal signs, strokes, and headache with papilledema caused by dural venous sinus thrombosis. Steroids can be used to treat the ocular and brain symptoms, but often do not affect the skin or genital lesions.20,​21

Primary CNS Vasculitis

Primary angiitis of the CNS often presents as a small-vessel vasculitis affecting leptomeningeal and parenchymal blood vessels. It presents as a subacute encephalopathy without systemic symptoms. Once suspected, brain biopsy is necessary to confirm diagnosis.20,​21

18.1.12  Fibromuscular Dysplasia

Etiology and Aneurysms

Fibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory, multifocal arterial disease which can involve any or all the three layers of the arterial wall and is classically associated with hyperplasia of the smooth muscle layer in the tunica media. It can lead to a propensity for focal irregularity of the blood vessels, stenosis, aneurysms, and increased risk for dissections and subsequent downstream organ dysfunction.21

Presentation

Many of these lesions are asymptomatic, however, they can lead to stenosis, thrombus formation, and dissections which can present as ischemic strokes or even uncontrolled hypertension if the renal arteries are affected. These patients may also have headaches, pulsatile tinnitus, cervical bruits, migraines, and may develop ­Horner’s syndrome if the cervical vasculature is affected.

Diagnosis

Diagnosis is made by CT angiography (CTA), MR angiography (MRA), or standard ­angiography. Classically, it can be visualized as the “string of beads” appearance ( Fig. 18.2).

Treatment

The mainstay of therapy consists of reducing other vascular risk factors and treatment with antiplatelet therapy such as aspirin. Calcium channel blockers are commonly used for hypertension and to

Fig. 18.2  String of beads sign on angiography (arrows).

prevent vasoconstriction. Those patients with hypertension should have evaluation of their renal arteries to rule out stenotic lesions.21

18.1.13  CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal dominant disorder, which leads to a variety of neurologic phenomenon including ischemic subcortical strokes, migraine with aura, depression, and dementia. CADASIL is due to a mutation in NOTCH3 gene which is important for vascular smooth muscle development. Molecular genetic testing is now the gold standard of diagnosis.22

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18.1.14  Neuronal Antibody Disorders

The following are some high-yield paraneoplastic syndromes and their associated antibodies and malignancies19:

•Anti-Ma1 antibody: Limbic and/or brainstem encephalitis. Occasional isolated cerebellitis. Associated with lung and testicular cancer.

•Anti-Ma2/Anti-Ta antibody: Limbic and/or brainstem encephalitis with excessive­ daytime sleepiness and vertical gaze. Associated with testicular germ cell tumors.

•Anti-Hu antibody: Encephalomyelitis with peripheral neuropathy. Associated with small-cell lung cancer.

•Anti-Ri antibody: Opsoclonus–myoclonus with retinal degeneration. Associated with breast cancer in adults, neuroblastoma in children.

•Anti-NDMA antibody: Encephalomyelitis with personality change. Associated with ovarian teratomas.

•Anti-Yo antibody: Cerebellitis and brainstem encephalitis. Associated with ovarian, uterine, and breast cancers.

•Anti–voltage-gated calcium channel antibody: Neuromuscular weakness. Also called as Lambert–Eaton syndrome. Associated with small-cell lung cancer.

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18.1.15  Epilepsy Syndromes

The following are some high-yield epilepsy syndromes, with characteristic features and treatment.23

•West syndrome (infantile spasms):

Sudden spasms of the head and trunk. Associated with hypsarrhythmia on EEG. Treat with adrenocorticotropic hormone (ACTH) and vigabatrin ( Fig. 18.3).

•Benign rolandic epilepsy: Nocturnal seizures only. Centrotemporal spikes (rolandic spikes) on EEG. Typically, self-limited but can be treated with carbamazepine or gabapentin ( Fig. 18.4).

•Lennox–Gastaut syndrome: Uncontrolled seizures with generalized, partial, and atonic (drop attack) seizures. Treatment with valproate, lamictal, and topiramate but often refractory ( Fig. 18.5).

•Juvenile myoclonic epilepsy (JME):

Interictal myoclonic jerks with generalized seizures. May have had “staring spells” in adolescence. A 4 to 6 Hz spike wave and polyspike discharges on EEG. Treatment with valproic acid is most effective.

•Absence epilepsy: Blank staring spells with no postictal period. A 3-Hz spike-wave discharges on EEG. Treatment with ethosuximide, or valproate if there are other seizure types as well.

Fig. 18.3  Hypsarrhythmia seen in West syndrome.