Wilderness Neurology

Published on 24/06/2015 by admin

Filed under Emergency Medicine

Last modified 24/06/2015

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 951 times

Chapter 33 Wilderness Neurology

For online-only figures, please go to www.expertconsult.com image

It is essential for practitioners in wilderness settings to have a working knowledge of neurology and to be able to diagnose and treat patients without recourse to specialist investigation, especially computed tomography and magnetic resonance imaging. Circumstances will vary depending on terrain, weather, and the availability of emergency transport (Figure 33-1, online).

This chapter focuses on common neurologic problems. Important neurologic problems within wilderness medicine are divided into three main groups:

Preliminaries: History and Examination

The majority of neurologic conditions can be diagnosed with the use of a minimum of tools with a combination of history, observation, and physical examination. Clinical diagnosis in neurology is highly reliable; in no other branch of medicine are disease patterns and physical signs more consistent and dependable.

This section outlines the rudiments of diagnosis, and stresses that a brief examination in combination with a succinct and practical formulation are essential. Written records should be maintained in all circumstances. In the event of any substantive illness and after any accident, one should inform the relevant insurance company, because many policies exclude coverage for late complications unless illnesses or accidents have been reported promptly. This holds true beyond neurology per se.

There is no substitute for a careful history from the patient, his or her companions, or witnesses. Until the practitioner learns the actual story of what happened, he or she should not jump to medical conclusions. For example, the person who has fallen to the ground while shaking has not necessarily suffered a seizure; there is a broad differential diagnosis.

Nervous system examination need not be lengthy or complex. A short neurologic examination (Box 33-1) takes less than 5 minutes. Much can be done without any special equipment; a tendon hammer can be improvised easily, and lack of an ophthalmoscope rarely makes a great difference to diagnosis and management.

Try to answer the following critical questions, using the story and examination findings:

Pattern recognition—and thus some experience—is vital. Try to take matters as simply as possible, gauge whether or not the case is truly serious, and review physical signs regularly. In wilderness settings, one may only be able to reach tentative conclusions. The substantial majority of all neurology cases turn out not to be sinister, and fortunately there are few true neurologic field emergencies where immediate action is vital.

Incidental Neurologic Conditions

Wilderness Guidelines for the Diagnosis of Headache

With any headache, first establish whether there is fever, a rash, or any “hard” neurologic signs, such as diplopia, papilledema, hemiparesis, or ataxia. If any of these is present, serious pathology must be considered. Papilledema may be difficult to detect with certainty in isolated circumstances. Easily visible retinal hemorrhages almost always accompany true disc edema. Consider the following questions:

Epilepsy

A seizure (i.e., a convulsion or “fit”) is caused by a paroxysmal discharge of cerebral neurons. Epilepsy is the continuing tendency to have seizures, even if a long interval separates the attacks. A generalized convulsion (i.e., a grand mal seizure) is the most common recognized event. More than 2% of the population in developed countries is known to have two or more seizures during their lifetimes; among 0.5%, epilepsy is an active problem. Around 200,000 people in the United Kingdom and around 1.5 million people in the United States take antiepileptic drugs.

Diagnosing a Seizure

Eyewitness accounts may be unclear and colored by the drama of the situation. Some stages of a seizure may be absent. With a primary generalized seizure, the typical stages are first the warning (i.e., a perception that something is about to happen but without a specific aura), which leads to the tonic (i.e., stiff or rigid) phase, during which the patient falls unconscious to the ground, sometimes first uttering a cry. Injuries are common, and the tongue may be severely bitten. Incontinence of urine, feces, or both may follow. The clonic (convulsive) phase begins, with bilateral rhythmic limb jerking and foaming at the mouth. This convulsive phase lasts from a few seconds to several minutes. The patient is typically cyanotic during the attack. Postictal drowsiness, confusion, or coma follows; this sometimes lasts for several hours, but it typically lasts for several minutes.

With a partial seizure, the sequence of events depends on the site of the seizure origin in the cortex. The patient may have an aura before the seizure begins. An aura is a specific and patterned sensation that is caused by a focal cortical electrical discharge.

With a simple Jacksonian partial motor seizure that has its origin within the motor cortex, the patient may sense a vague warning (as with a primary generalized seizure) that is followed by a specific aura (e.g., unusual sensations in one limb). This is followed by the onset of rhythmic jerking, typically in one hand or foot. Jerking spreads to the entire limb or to both the upper and lower limbs and possibly the face on the same side. This progression is known as the “march” of the seizure. Consciousness is not lost during a simple partial seizure. In place of postictal drowsiness or coma, weakness of the limbs that were involved with the seizure may follow. This is known as Todd’s paralysis, and it may last for several hours. A stroke may be suspected if early stages of the seizure were not witnessed or if they are unclear.

With a complex partial seizure of temporal lobe origin, the patient may experience an aura of familiarity with his or her surroundings, which is known as déjà vu; this is followed by an “absence attack” during which the patient is generally unaware or disoriented. As the seizure develops, the patient looks distant (i.e., appears to be in a trance-like state) and does not respond to stimuli. Facial or lip twitching may occur. Recovery is typically rapid, with the patient regaining full awareness in a matter of seconds or minutes (and rarely in more than 10 minutes).

A focal seizure may progress to become secondarily generalized. For example, a Jacksonian motor seizure may develop into a grand mal fit.

The usual differential diagnosis of a seizure is between syncope and a nonepileptic attack. There are many causes of loss of consciousness or sudden attacks; these are described later in this chapter. Assuming that one knows what to expect, they are usually recognizable.

Emergency Management of Seizures

In the field, a seizure may well take place in a sensational situation, such as on a glacier, on a steep path, on a climb, or at sea. The doctor’s actions are frequently very much in the public view, and there is often an expectation that skilled and urgent treatment must be seen to be underway. The reality is that careful observation is usually the most important activity.

Immediately establish and maintain a patent airway. Do not force the patient’s mouth open. Wooden mouth wedges, tongue forceps, and excessive restraint are likely to cause more injuries than will any seizure. Deep cyanosis is typical during a grand mal fit. The spontaneous return of normal breathing and oxygenation will remedy the problem.

If an attack lasts for more than a few seconds, stay with the patient, summon help, assist with breathing, and establish intravenous access, if possible. The latter is unlikely to be necessary, but it prepares the patient for the medical emergency of status epilepticus. Most seizures resolve spontaneously.

Status Epilepticus

Status epilepticus, which is also known as status (Box 33-2), involves the occurrence of continuous seizures (two or more) without fully recovering consciousness. More than 50% of cases of status occur without a previous history of epilepsy. Status is associated with a mortality rate of 10% to 15%.

Around 25% of patients with apparent refractory status have pseudostatus, which is also known as nonepileptic attack disorder (NEAD). Although the apparent status is factitious, there are great difficulties when it comes to making a confident diagnosis in this emergency situation.

Not all status is convulsive. With absence status, the patient is in a continuous, distant, and stuporous state. The term focal status

Buy Membership for Emergency Medicine Category to continue reading. Learn more here