Bma Illustrated Medical Dictionary

The sciatic nerves

are formed from

nerve roots in the

spinal cord.

scintigraphyAn

alternative name

for radionuclide

scanning.

scirrhousA term

that means hard

and fibrous and is

usually applied to

malignant tumours

containing dense,

fibrous tissue.

sclera The white

fibrous outer coat

that protects the

eye from injury.

The most com-

mon disorder of

the sclera is scleritis. In osteogenesis

imperfecta, the sclera is very thin.

scleritisInflammation of the sclerathat

usually accompanies a collagendisease

such as rheumatoid arthritis. Scleritis also

occurs in herpes zoster ophthalmicus and

Wegener’s granulomatosis. It may lead to

areas of thinning and perforation of the

sclera. It is usually persistent but often

responds to corticosteroideye-drops.

sclerodermaSee systemic sclerosis.

scleromalaciaSoftening of the sclera,

commonly a complication of scleritis,

especially scleritis of rheumatoid arthritis.

sclerosing cholangitisA rare condition

in which many of the bile ducts are nar-

rowed, causing progressive liver damage

for which the only treatment may be a

liver transplant. (See also cholangitis.)

sclerosisA medical term for hardening

of a body tissue, usually used to refer to

hardening of blood vessels (as in arterio-

sclerosis)or of nerve tissue (as occurs in

the later stages of multiple sclerosis).

sclerotherapy A method of treating

varicose veins, especially in the legs;

haemorrhoids;and oesophageal varices.

The vein is injected with an irritant solu-

tion, which causes inflammation in the

vessel lining, leading to scar tissue for-

mation and the obliteration of the vein.

scoliosisA deformity in which the spine

is bent to one side. The thoracic or lum-

bar regions are most commonly affected.

various forms of delusionssuch as those

of persecution (which are typical of

paranoid schizophrenia);hallucinations,

which are usually auditory (hearing

voices), but which may also be visual or

tactile; and thought disorder, leading to

impaired concentration and thought

processes. Disordered thinking is often

reflected in muddled and disjointed

speech. Behaviour is eccentric, and self-

neglect common. In a rare form of

schizophrenia, catatonia may occur, in

which rigid postures are adopted for

prolonged periods, or there are out-

bursts of repeated movement.

Diagnosis of schizophrenia may take

some time and, in some cases, it may

be difficult to make a diagnosis at all.

Treatment is mainly with antipsychotic

drugs, such as phenothiazine drugs, and

new atypical antipsychotic drugs such

as risperidone. In some cases, the drugs

are given as monthly depot injections.

Once the symptoms are controlled,

community care, vocational opportu-

nities, and family counselling can help

to prevent a relapse.

Some people may make a complete

recovery. However, the majority have

relapses punctuated with partial or full

recovery. A small proportion have a

severe life-long disability.

sciaticaPain that radiates along the sci-

atic nerve. The pain usually affects the

buttock and thigh, sometimes extending

down the leg to the foot. In severe cases,

the pain may be accompanied by numb-

ness and/or weakness in the affected area.

The most common cause is a prolapsed

intervertebral disc pressing on the nerve

root (see disc prolapse). Other causes

include a muscle spasm, sitting awkward-

ly for long periods, or, less commonly,

pressure on the nerve from a tumour.

Sometimes the cause is unknown.

Treatment of sciatica is with analgesic

drugs. If the pain is severe, a short per-

iod of bed rest may be helpful, although

prolonged rest may cause the condition

to worsen. Physiotherapy, osteopathy, or

chiropracticmay help in some cases. It

is important to maintain a healthy

posture and weight.

sciatic nerveThe main nervein each

leg and the largest nerve in the body.

SCIATICA SCOLIOSIS

S

Spinal

nerve

root

Sciatic

nerve

SCIATIC NERVE

Spinal

cord