General cerebral symptoms
The development of general cerebral symptoms in various neuroinfections is directly associated with two main factors: increased intracranial pressure and direct toxic effects on brain structures. Several classic manifestations are distinguished in the clinical picture.
Headache (cephalalgia) As a rule, it is extremely intense and bursting in nature. Patients describe it as one of the worst pains they have ever experienced.
Vomiting of central origin This is one of the most prominent and specific signs. Unlike gastroenterological pathology, vomiting associated with central nervous system lesions has certain features:
- Occurs suddenly, without any preceding nausea.
- Completely unrelated to food intake.
- Does not bring the patient even temporary relief.
- Occurs due to direct irritation of the vomiting center located in the medulla oblongata.
Hyperesthesia Patients exhibit pathologically heightened sensitivity to any external stimuli. This phenomenon is explained by the irritation of sensitive spinal nerve roots by altered cerebrospinal fluid (CSF). The main types of hyperesthesia include:
- Photophobia (painful reaction to bright light).
- Hyperacusis (intolerance to normal or loud sounds).
- General cutaneous hyperesthesia (painfulness to ordinary touch).
Meningeal signs: the basic triad
The foundation of meningeal syndrome is irritation of the meninges. The body responds with a reflex increase in tonic muscle tension, forming the so-called protective muscular defense.
The key triad that a physician must check when suspecting meningeal involvement includes nuchal rigidity, as well as Kernig's and Brudzinski's signs.
1. Nuchal rigidity Manifests as marked tension in the muscles of the posterior neck. The physician cannot passively bring the patient's chin to their chest due to strong muscular resistance.
2. Kernig's sign The technique for performing this maneuver is strict and requires proper patient positioning:
- Execution: The physician flexes the leg of a supine patient at a right angle (90 degrees) at both the hip and knee joints simultaneously. Afterwards, an attempt is made to passively extend the leg at the knee.
- Positive reaction: The physician is unable to fully straighten the patient's leg. This is hindered by a pronounced reflex spasm (tonic tension) of the hamstring muscles.
3. Upper Brudzinski's sign
- Execution: The patient is in the supine position. The physician passively flexes the patient's head toward the chest (in fact, nuchal rigidity is also assessed at this exact moment).
- Positive reaction: In response to bringing the head to the chest, the patient exhibits an involuntary reflex flexion of the lower extremities at the hip and knee joints — the legs are reflexively pulled toward the abdomen.
Differential diagnosis: meningism and meningitis
A crucial physician skill is the correct clinical interpretation of identified symptoms. It must be clearly understood that the mere presence of nuchal rigidity and positive Kernig's and Brudzinski's signs indicates exclusively meningeal irritation syndrome.
These signs are not absolute and indisputable proof that the patient has developed true infectious inflammation of the meninges, i.e., meningitis.
Meningism phenomenon In clinical practice, a condition called meningism is frequently encountered. In this state, the full complex of meningeal symptoms appears against the background of severe general bodily intoxication (e.g., in severe influenza or massive pneumonia). Meanwhile, there is no real inflammatory process in the meninges themselves, and the symptomatology is driven by toxic or hemodynamic effects.
Gold standard of verification Given the impossibility of distinguishing meningism from meningitis based solely on physical examination results, a strict algorithmic approach exists.
To definitively confirm or rule out a diagnosis of meningitis, performing a lumbar (spinal) puncture is strictly necessary. Following CSF collection, a thorough laboratory analysis is performed. The main criterion for true meningitis will be the detection of inflammatory changes in the cerebrospinal fluid, primarily cellular pleocytosis.
To easily memorize the essence of Kernig's sign, use a first-letter association: Kernig — Knee (it is impossible to extend the leg specifically at the knee joint after prior flexion).
Class and exam questions
Why does vomiting in meningeal syndrome bring no relief to the patient?
This vomiting has a central origin. It is caused by direct toxic irritation of the vomiting center located in the medulla oblongata, rather than food poisoning or gastrointestinal issues.
Does the presence of Kernig's and Brudzinski's signs mean a 100% diagnosis of «meningitis»?
No. These symptoms only indicate the presence of meningeal irritation syndrome. They can also be observed in meningism — a reaction of the meninges to severe general intoxication (e.g., in influenza) without true inflammation.
What is the gold standard for confirming meningitis?
Meningitis can only be definitively confirmed or ruled out by performing a lumbar (spinal) puncture followed by laboratory analysis for signs of inflammation (pleocytosis) in the CSF.
What else to study on this topic
- Technique of lumbar puncture
- CSF characteristics and types of pleocytosis
- Middle and lower Brudzinski's signs
- Mechanisms of intracranial hypertension development
Master the entire topic in the Pediatrics course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on «Meningeal syndrome» and another 3,738 subject pages
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 71 video lessons on the subject
Other topics from the section «Chapter 12. Infectious and parasitic diseases»
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.