Neurological Presentations

Usually, patients do not present with a confirmed diagnosis ready for treatment. There are common neurological presentations (or problems) that we face as neurologists. In this section, we introduce the general approach to neurological presentations. After that we outline a simple approach to the commonest neurological presentations (or problems). We will introduce the basic concepts of how we arrive at a reasonable differential diagnosis from the clinical assessment; the history and physical examination.
In this section the information will be kept accessible. The goal is to give you a framework to approach neurological presentations. For more advanced clinical assessment, there are better texts, however, the simple approach works most of the time. At the very least it will get you started.

The general approach to neurological disease:

Classic Neurology 2 basic questions:
1.       Where is the lesion?
2.       What caused the lesion?
Modern Neurology 4 basic questions:
1.       What is the medical problem/presentation?
2.       Where is the lesion?
3.       What caused the lesion?
4.       What are we going to do about it?

Here is an explanation of how to use these questions to frame your approach to the patients problem:
1.       What is the medical problem/presentation?
Before you can deal with the problem it is helpful to identify the problem or presentation. This requires translating what the patient and witnesses tell us into medical terminology. Are we dealing with a focal motor deficit? or is this a paroxysmal loss of consciousness? or should we employ the approach to coma? or is the a case of a dizzy patient? furthermore is the dizziness vertigo, pre-syncope or ataxia?
Spending time to identify what presentation we are dealing with will help plan the clinical assessment.
2.       Where is the lesion? (this is based on the DISTRIBUTION OF DEFICISTS )
This is a very important question to try to answer before moving one to thinking about the etiology of the lesion. First, you should try to determine where in the nervous system is the lesion, or area of dysfunction. Is it in the brain, the spinal cord, the peripheral nervous system, the neuromuscular junction, the muscles or in the sensory organs? Try to spend some effort getting to a closer localization e.g. if you think the lesion is in the brain, is it in the right or left hemisphere? in the cortex or subcortical areas? is the lesion in the brainstem? if so, is it in the midbrain, pons or medulla?
To determine the lesion localization, the distribution of the deficits and knowledge of the functional anatomy of the nervous system are the most useful features. The physical exam and to an extent the history will help you decide the distribution of the deficits.
The reason this step is important is because it helps us narrow down the differential tremendously which in turn allows for a more efficient investigation and treatment plan.
3.       What caused the lesion?
Similar to how determining lesion localization is based on the distribution of deficits, determining lesion etiology/pathogenesis is based primarily on temporal features (onset, duration, episodic vs persistent) and to a lesser extent co-morbidities, risk factors and other associated features. For example stroke presents with acute onset of deficits, brain tumors present with gradual onset of deficits and demyelinating disease present with gradual onset deficits that may remit or relapse.
Think along the major mechanisms of disease (see mnemonics below) as they apply to the lesion location:

Vascular Vascular
Infectious Inflammatory
Neoplastic Trauma, Toxin, other injuries
Degenerative Autoimmune
Idiopathic Metabolic, Medication
Congenital Infection
Autoimmune Neoplastic
Trauma Congenital
Endocrine/Metabolic Degenerative
Drugs Endocrine

4.       What are we going to do about it?
This question prompts us to think about our investigation plan and treatment plan including any emergent interventions if necessary. This is commonly referred to as the “management plan” or plan of care.

This 4 step process is not confined to neurology or motor deficits, clinicians use it when dealing with vomiting for example. Is it vomiting or hematemasis, is it GIT or systemic, is it in the foregut (gastric outlet obstruction), midgut (small bowel obstruction), or hind gut (large bowel obstruction). What caused it chronic duodenal ulcer, pyloric stenosis, tumour, adhesion, hernia, meningtitis, etc. What are we going to do about it? Ultrasound, CT, ERCP, blood tests, amylase levels, fluids, antibiotics, surgery etc.

Disorders are also divided as persistent vs. paroxysmal:
Persistent (Diffuse vs. focal) vs. paroxysmal disorders (diffuse vs. focal):
Paroxysmal disorders have additional features that need to be inquired about:
1.       Duration
2.       Frequency
3.       Pre-episode (pre-ictal) features
4.       During the episode (ictal) features
5.       Post-episode (post-ictal) features

Approach to the main neurological presentations:

Approach to weakness “focal motor deficits”
Approach to sensory deficits
Approach to abnormal speech
Approach to cognitive impairment
Approach to acute confusion “altered mental status”
Approach to coma
Approach to dizziness
Approach to headache
Approach to diplopia
Approach to visual loss
Approach to movement disorders and ataxia

Transient and paroxysmal events:
Approach to transient (or paroxysmal) loss of consciousness
Approach to transient (or paroxysmal) focal events