Shift of the mediastinum

In a couple of the CRAM case studies for my exam there are reports from a CXR of a shift of the mediastinum to either left or right.

I've now found out what the most common cause for this is, pneumothorax (collection of air in the pleural cavity). However there are different types of pneumothorax and each one causes a shift in a different direction. Here's why...

TENSION PNEUMOTHORAX

Usually occurs as a result of trauma (e.g. a stab wound) and results in an accumulation of air under pressure in the pleural cavity. The wound (or opening) acts as a 'one way valve' allowing air in to the thorax but not out.

In this case the mediastinum would shift AWAY from that area (e.g. if it was a left lung tension pneumothorax the mediastinum would shift to the right). This is due to pressure gradients and the fact that it's encourage to move from an area of high pressure to low pressure.

SPONTANEOUS PNEUMOTHORAX

PSP (primary) refers to those without chronic lung conditions

Secondary refers to those with underlying lung disease

In this case the lung would collapse but there's no 'one way valve' effect letting air in and not out. Therefore the pressure on the side of the collapse is lower than the contralateral side...meaning that the mediastinum shifts TOWARDS the collapsed lung!

Meninges - Membranes surrounding the brain and spinal cord

Dura Mater - Outermost layer

Tough, inflexible and 'leather like'.

Lines the inside of the skull where it's attached to the bones.


Arachnoid mater - Middle layer (separated from the pia mater by the subarachnoid space)

Delicate spider-web like structure

Attached to the inside of the dura

Surrounds the inside of the brain and spinal cord
(aracnoidea encephali & spinalis)


Pia mater - Delicate innermost layer

Thin / mesh like

Closely envelops entire surface of brain

Runs down fissures of the cortex

Supplies brain tissue with blood vessels



Subarachnoid space - Between arachnoid mater and pia mater is the CSF which absorbs and disperses excessive mechanical forces that might otherwise cause serious injury. It's produced by the choroid plexuses in the lateral ventricles and drains into the dural venous sinus into the internal jugular vein.

Slump Test

1) Patient sits with thighs fully supported on plinth / hands clased behind their back

2) Patient is instructed to slump shoulders towards groin

3) Physio applies gentle over pressure to this trunk flexion

4) Patient adds cervical flexion / maintained by therapist

5) Patient performs unilateral knee extension / active dorsiflexion

6) Patient is instructed to extend neck. If cervical extension causes a decrease in symptoms this is a +ve finding indicating ABNORMAL NEURODYNAMICS

TIA

TIA = transient ischaemic attack

Briefl focal loss of function with full recovery occuring in 24hrs

5-10% of people who experience this will go on to have a stroke.

STROKE

A stroke is also known as a CEREBROVASCULAR ACCIDENT (CVA)


It usually results in HEMIPLEGIA (paralysis to one side of the body) which is contralateral to the side of the brain in which the lesion occurs e.g. stroke on L = hemiplegia on the R

An interruption of blood flow to the brain leaves the patient with a focal loss of function of varying severity.

Motor deficit is the the most common but other neurological deficits can include:

• Visual
• Perceptual
• Sensory
• Communication
• Swallowing

84% of strokes are ISCHAEMIC in origin

• Cerebral thrombosis (mainly affects older population with Hx of high cholesterol)

When a thrombus (blood clot) develops in a cerebral artery (usually one affected by atherosclerosis)

• Emobolic (mainly affects those with heart disease/previous heart surgery)

When a clot forms elsewhere in the body and becomes lodged in a cerebral artery

16% of strokes are HAEMORRHAGIC in origin

Major Risk Factors:

• Hypertension
• Raised cholesterol
• Cardiac disease
• Diabetes
• Smoking
• Atherosclerosis

Minor Risk Factors:

• Obesity (too much Maccie Dees!)
• Physical inactivity (being a lard arse!)
• Contraceptive pill (use a condom!)
• Excessive alcohol consumption ('boozing'!)

http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/neurology/ischemic-stroke/

ISCHAE

Finding the culprit

Yesterday's physio session at Ox city after the game revealed a new lesson after discussion with Leigh.

Player comes in complaining of tightness in anterior proximal thigh.

Q. Which muscle is it?

Process: Think what's likely to be tight in footballers? Running. What muscles originate from that area?

A. Narrowed it down to rec fem and sartorius. You had to palpate deep but resisted isometric strength test for sartorius came out on top. Resisted hip flexion did not.

The process of elimination!

I was helping out at Ox city footy club again earlier this week and we came across an acute adductor strain. When trying to diagnose which adductor muscle it was I was given a handy tip by Leigh:

"it's easier to cross off all the one's it's not than try to immediately pick which one it is"

Turned out to be adductor magnus after I'd originally guessed gracilis. When I thought about it, you could quickly cross off pectineus and brevis because they're only one joint muscles and much higher up than where the patient was complaining. Longus potentially but the magnus 2 heads:

Oblique head
ORIGIN: inferior ramus of pubis & ischial ramus
INSERTION: gluteal tuberosity, linea aspera, proximal supracondylar line of femur

Vertical head (hamstring head)
ORIGIN: ischial tuberosity
INSERTION: adductor tubercle

Remember that anatomically speaking the oblique head FLEXES & ADDUCTS the thigh @ hip
(much like pectineus) and the vertical head EXTENDS thigh at hip (like a hamstring!)

The important thing to remember though is that these muscles work differently in function, but that's for another day.