The nervous system is composed of gray and white matter in different configurations depending on the location within the nervous system

– Within the brain, grey matter is on the outside and white matter on the inside, while in the spinal cord this is the reverse (see Figures 4, 11)

SAME DAVE is the mneumonic that can be used for remembering the relationships and locations between nerves and the spinal cord

– SAME: Sensory-Afferent; Motor-Efferent

– DAVE: Dorsal-Afferent; Ventral-Efferent

• Ependymal cells line the ventricles and the choroid plexus

o Responsible for cerebrospinal fluid (CSF), approximately 150mL, in circulation

Traumatic Brain Injury (TBI)

Brain injury is leading cause of death and disability for Canadians under the age of 40

~1.5 M Canadians live with the effects of an acquired brain injury

The annual incidence of ABI is > that od MS, SCI, HIV/AIDS and Breast Cancer combined!

Etiology

Caused by any accident in which head trauma occurs

– Damage can be at the site of impact (coup) or opposite (contrecoup) from recoil, and often both occur as the brain impacts the interior of the cranium

– Common examples include: Transportation (vehicle and pedestrian collisions), falls (particularly in older adults), sports-related, violence

Types of trauma:

Closed (blunt, non-missile) trauma

Open (penetrating, missile) trauma

Pathophysiology:

Brain hematoma develops following trauma

May be located in one of 3 spaces between meningeal layers

– Epidural

– Subdural

– Intracerebral

Focal or diffuse neuronal injury occurs

– As blood accumulates, there is increased pressure within the cranium which damages neurons to produce clinical symptoms

– Clinical symptoms are dependent on the location of injury

Focal injury is localized to specific brain regions area

Diffuse neuronal (axonal) injury (DAI) occurs when there is a twisting of the brain within the cranium producing shearing forces that effectively shred the axons themselves

– DAI generally produces more severe symptoms and prognosis

Concussion

Mild TBI causing alteration in brain functions +/- loss of consciousness

Common causes include (blunt head trauma, car crash, physical assault, falls)

Clinical manifestations:

Mild concussion:

– Immediate but transient clinical manifestations; 1 to several minutes, possibly with amnesia

Classic cerebral concussion

– Loss of consciousness < 6 hours

– Amnesia with confusional state lasting hours to days

General manifestations of concussion

– Headache

– Sleep disturbance

– Nausea and/or vomiting

– Blurred vision

– Attention impairment

– Reduced processing speed

– Drowsiness

– Emotion/behavior changes

– Posttraumatic seizure

o If the patient is going to have a seizure it will usually occur within the first 24h following the traumatic event

Prognosis

Symptoms are usually transient, with peak of symptoms occurring in the first 18-36 hours

May experience full recovery or a range of residual impairments from mild (i.e. increased sensitivity to sound or light) to severe (i.e. permanent cognitive or physical impairment)

Fractures of the Spine

Types:

Simple fracture

– Single break usually affects transverse or spinous process

Compression fracture

– Vertebral body compressed anteriorly

Comminuted (burst) fracture

– Vertebral body shattered into several fragment

Dislocation

– Vertebral body slides on another

Location:

Most common fracture locations are:

– Cervical (1, 2, 4-7)

– T1-L2

Pathology and complications:

Spinal cord injuries due to compression of spinal cord parenchyma, central canal and vascular structures

Spinal Cord Injuries (SCI)

Causes:

Hyperextension injury

Flexion injury

Axial compression injury

Flexion-rotation injury

Pathophysiology:

Hemorrhage in grey matter and pia-arachnoid region of the meninges

– Increases in size until entire grey matter is hemorrhagic and necrotic

Edema in white matter

– Microcirculation block that reduces vascular perfusion to the region leading to ischemia and necrosis

– Maximum pathology from hemorrhages and edema occur at the level of injury + 2 segments above and below

It takes 24 h regain circulation in white matter and longer to gray matter

Inflammation and healing start 36-48 h

Collagen replacement/repair in 3-4 weeks

Spinal shock:

– Stopping of spinal cord activities at and below the level of injury

– Complete loss of reflex function (skeletal, bladder, bowel, thermal control, and autonomic control) below level of lesion

o May last from a few days to 3 months with an average of 7-20 days

o Ends with reappearance of reflex activity, hyperreflexia, spasticity, and reflex emptying of the bladder

Complications of spinal cord injuries

Paraplegia:

– Lesion in thoracic, lumbar, or sacral regions

– Impairment in motor, sensory functions of the lower limbs

Quadriplegia:

– Lesion at high level C1–C7

– Impairment in motor or sensory function of all limbs and torso

Degenerative Disorders of the Spine

Degenerative Disc Disease (DDD)

Progressive disease common in individuals over the age of 30 related to structural defects from loss of cartilage in the spine leading to vertebral compression

Both part of the normal aging process as well as having genetic component involving genes that code for cartilage in the spine

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