Color Atlas of Neurology

Cervical muscle weakness

Proximal muscle weakness and atrophy

Ischemic lesion of muscle fiber

Perifascicular atrophy (DM; cross section of muscle fiber)

Lymphomonocytic infiltrate in muscle, vessel (PM, cross section of muscle fiber)

Lid edema

Facial erythema

Proximal muscle weakness

Telangiectasis,

Polymyositis (PM) hemorrhage (nailbed)

Erythema in joint region (extensor side)

Dermatomyositis (DM)

Distal muscle atrophy

Bleeding

an autosomal dominant trait (gene loci: 19q13.1, 17q11–24, 7q12.1, 5p, 3q13.1, 1q32). The creatine kinase level may be chronically elevated in susceptible individuals, who can be identified with an in vitro contracture test performed in specialized laboratories. Persons suffering from central core disease, multicore disease, and King–Denborough syndrome (dwarfism, skeletal anomalies, ptosis, high palate) are also at risk for MH. Treatment: dantrolene.

Malignant neuroleptic syndrome clinically resembles MH; unlike MH, however, it is usually of subacute onset (days to weeks), it is not hereditary, and it is triggered by psychotropic drugs (haloperidol, phenothiazines, lithium). Malignant neuroleptic syndrome can also be induced by abrupt withdrawal of dopaminergic agents in patients with Parkinson disease.

Toxic Neuromuscular Syndromes

The muscle fiber lesions regress if the responsible substance is eliminated in timely fashion (Table 75, p. 405).

Myopathy in Endocrine Disorders

Hyperthyroidism or hypothyroidism, hyperparathyroidism, Cushing syndrome, steroid myopathy, and acromegaly all cause proximal weakness, while Addison disease and primary hyperaldosteronism usually cause generalized weakness. Timely correction of the endocrine disorder or withdrawal of steroid drugs is usually followed by improvement.

Critical Illness Polyneuropathy (CIP)

and Critical Illness Myopathy (CIM)

Sepsis is the most common cause not only of encephalopathy (see p. 312) but also of CIP and CIM. CIP is an acute, reversible, mainly axonal polyneuropathy. It causes distal, symmetric weakness with prominent involvement of the muscles of respiration, resulting in prolonged ventilator dependence and delayed mobilization. CIM causes generalized weakness. The clinical differentiation of CIM and CIP is difficult and often requires muscle biopsy.

Paraneoplastic Syndromes

(Table 76, p. 406)

Distant neoplasms can affect not only the CNS (see p. 388) but also the PNS and skeletal muscle. Remarkably, paraneoplastic syndromes sometimes appear months or years before the underlying malignancy becomes clinically manifest. Paraneoplastic neuromuscular syndromes typically present with marked weakness of subacute onset (i.e., developing over several days or weeks).

A detailed description of diagnostic evaluation procedures can be found in the textbooks listed on p. 409. The goals of history-taking, physical examination, and additional testing (if necessary) are:

!Data collection (manifestations of disease)

!Localization of the lesion

!Provision of an etiological diagnosis

"Data Collection

The diagnostic process begins with the history and physical examination. The history provides information about the patient’s experience of illness, the temporal course of symptom development, and potentially relevant familial, social, occupational, and hereditary factors. An inaccurate or incomplete history is a frequent cause of misdiagnosis.

History. The physician engages the patient in a structured conversation about the manifestations of the illness. The physician must remember that the patient is the “expert” in this situation, as the patient alone knows what is troubling him (though perhaps helpful information can also be obtained from a close relative or friend). The physician aims to obtain accurate information on the nature, location, duration, and intensity of the symptoms by listening patiently and asking directed questions in an atmosphere of openness and trust. Questionnaires, computer programs, and ancillary personnel cannot be used for primary his- tory-taking, as they do not enable the construction of a trusting physician–patient relationship (though they may provide useful additional information at a later stage). Some important elements of the case history are as follows.

!Nature of symptoms. The physician must ascertain, by detailed questioning if necessary, that he understands the patient’s complaints in the same sense that the patient means to convey. “Blurred vision” may mean diplopia, “dizziness” may mean gait ataxia, “headache” may mean hemicrania, “numbness” may mean paresthesia—but patients may use all of these terms with other meanings as well.

!Severity of symptoms. Quality and intensity of symptoms, activities with which they interfere.

!Onset of symptoms. When, where, and over what interval of time did the symptoms arise?

!Time course of symptoms. How did they develop? Are they constant or variable? Are there any exacerbating or alleviating factors?

!Accompanying symptoms, if present.

!Past history of similar symptoms.

!Previous illnesses and their outcome.

!Social, occupational, and family history.

!Medications, smoking, alcohol abuse, substance abuse, toxic exposures.

!Previous diagnostic studies and treatment.

!Information from third parties may be needed for patients with aphasia, confusion, demen-

tia, or impairment of consciousness.

Physical examination. The general and neurological physical examination may yield important clues to the disease process, but only if the examiner has the requisite knowledge of the underlying principles of (neuro-)anatomy, (neuro-)physiology, and (neuro-)pathology. The examination is guided by the case history, i.e., the patient’s complaints and general physical condition determine what the examiner looks for in the examination. The unselective, “shotgun” application of every possible technique of neurological examination in every patient is not only a waste of time and money; it generally only creates confusion rather than clarifying the search for the diagnosis. The neurological examination of small children, patients with personality changes or mental illness, and unconscious patients poses special challenges.

Important elements of the neurological examination include:

!Inspection. Dress, appearance, posture, movements, speech, gestures, facial expression.

!Mental Status. Orientation (to person, place, and time), attention, concentration, memory, thought processes, language function, level of consciousness.

!Cranial nerves. Olfaction, pupils, visual fields, eyegrounds, eye movements, facial movement, facial sensation, hearing, tongue movements, swallowing, speaking, reflexes.

!Motor function. Muscular atrophy/hypertrophy, spontaneous movements, coordination, paresis, tremor, dystonia, muscle tone.

!Reflexes (p. 40).

!Sensory function. The findings of sensory testing are heavily influenced by the patient’s “sensitivity” and ability to cooperate. Vague sensory abnormalities without other neurological deficits are difficult to classify; their interpretation requires a good knowledge of the underlying neuroanatomy (pp. 32ff, 106f).

!Posture, station, and gait. The observation and testing of posture, station, and gait provides important information about a possible motor deficit (p. 42 ff).

!Autonomic function. The patient is questioned about bladder function, bowel movement/control, sexual function, blood pressure, cardiac function, and sweating, and is examined as needed.

"Localization of the Lesion

The findings of the history and physical examination findings are then related to dysfunction of a particular neuroanatomical structure(s) (p. 2 ff) or neurophysiological process (p. 40 ff); the site of the patient’s problem is thus localized (topical diagnosis).

" Provision of an Etiological Diagnosis

Once the site of the problem is localized, it must be determined whether it is due to a structural lesion (e. g., hemorrhage, nerve compression, or infection) or a functional disturbance (e. g.,

epileptic seizure, migraine, or Parkinson disease). The line between structural and functional pathology is not perfectly defined, as there is constant interaction between these two levels; at the same time, considerations of etiology and pathogenesis also influence data interpretation. The diagnostic process ideally ends in the diagnosis of a specific disease entity (nosological diagnosis).

Additional Diagnostic Studies

The clinical diagnosis may be considered firmly established by the history and physical examination alone in many cases, e. g., migraine or Parkinson disease. Additional diagnostic studies are merely confirmatory and are generally not needed unless doubt arises as to the diagnosis, e. g., if an epileptic seizure or new type of headache should appear.

Additional studies are needed, however, if there is no other way to decide among several diagnostic possibilities remaining after thorough his- tory-taking and physical examination. The number and type of studies needed differ from case to case. Studies that are costly or fraught with nonnegligible risk should never be ordered except to answer a clearly stated diagnostic question. The potential benefits of a proposed study must always be weighed against its risks and cost.

" Laboratory Tests

Table 77, p. 407