Role of Patient History and Physical Examination in the
Role of Patient History and Physical Examination in the
The diagnosis of facial pain has been a source of confusion for neuroscientists and primary care givers alike. The profusion of various subtypes, differential syndromes, and confusing nomenclature is silent testimony to this dilemma. The author presents a simple scheme with which to arrive at the diagnosis. The use of the patient's history, confirmed by the physical examination, can be supplemented with some of the tests described herein.
Trigeminal neuralgia is a well-known condition; neuroscientists working in the fields of neurology and neurosurgery are well acquainted with the syndrome. The diagnosis is made nearly entirely based on the patient's history. It should be a simple matter for physicians to make the proper diagnosis, but it is not. In a survey of patients with TN, 90% had experienced pain for more than 1 year before receiving an accurate diagnosis, whereas 13% went 10 years without a diagnosis. With an incidence of four cases per 100,000 in the US, individual practitioners in medicine and dentistry will see very few cases of TN in their careers. The rarity of the cases contributes to the rates of misdiagnosis and inappropriate treatment. Indeed, Tew and van Loveren found that 33% of their 1100 patients with TN had undergone unnecessary dental extractions.
First described in the 1600s, the clinical picture is one of pain and symptoms confined to the facial area; there are no systemic components to TN. Wartenberg suggested that the hallmarks of TN would be paroxysms of pain confined to one or more of the three divisions of the trigeminal nerve. The pain is predominantly unilateral, and is described as electric, lancinating, focal, and sharp. It can last for seconds to minutes initially, and sometimes lasts as long as 1 hour. Usually the patient is symptom free between attacks. Later in the course of the disease, patients report dull, aching, constant pain in the same distribution as the paroxysms.
Most patients experience a cyclic history of the pain, with the interval between attacks lasting weeks, months, and occasionally years (most patients experience a shortening of the interval between attacks in the course of a decade). Often, the interval between attacks is marred by an increasing level of paresthesias in the nerve. If questioned, patients will frequently report sensations of clicking in the ipsilateral ear, possibly related to the motor innervation of the tensor tympanii. There can be pain in the external auditory canal, in the area subserved by the trigeminal nerve. The external auditory canal is innervated by the ninth, 10th, and fifth cranial nerves and by the geniculate ganglion. The trigeminal and vagoglossopharyngeal nerves supply the majority of the external auditory canal; this is the correlation with the auricular pain.
The pain can be triggered by nonnoxious stimuli (chewing, talking, wind on the face, cold, and light touch). The classic trigger(s) will produce pain in divisions beyond the one so stimulated. The trigger represents allodynia in facial pain. This is due to central sensitization in addition to the peripheral initiator. Allodynia is the result of A-beta fiber activity with neuronal reorganization at the level of the dorsal root ganglion and rostrally. Many patients will describe a sense of pulling, fullness, and flushing in the affected area of the face. The patient usually can describe the first attack in detail, as to the time, place, associated events, and pain course. The pain can also be triggered by positional changes of the head. Typically, lying down on the side of the pain will provoke an attack, whereas rolling to the other side can minimize it. Patients will attribute pain at night more to these positioning phenomena than to contact with bedsheets in sleep. This correlates with the same position-provoked pain during the day.
There can be a family history in approximately 5% of patients with TN. Five percent of patients will experience bilateral sequential pain. More women may present than men (7.2 compared with 4.7 per 100,000), with the peak decade of presentation being the sixth. The age range at presentation in my experience is 22 months to 94 years. There is some controversy about the frequency of side of presenta-tion. White and Sweet reported right-sided pain in 61%, left-sided in 36%, and bilateral in 4%. Investigators in other studies did not find a propensity for one side or another.
Systemic illnesses such as multiple sclerosis, Lyme disease, and Charcot-Marie-Tooth disease can be part of the cause of the pain. Chiari malformations may exacerbate the pain of various cranial nerves, including the trigeminal nerve, as can other pathological phenomena discussed in the Differential Diagnosis section. These conditions can produce sequential pain on the contralateral side, or increased incidence of bilateral pain. Most often the pain is due to vascular cross-compression of the root entry zone (Fig. 1) of the main sensory root of the trigeminal nerve, the portio major, in the posterior fossa. This can include the area of the mixed motor and sensory fibers of the motor root, the portio minor. It may well be that cross-compression in this latter region produces the symptoms of facial pulling, facial fullness, and heaviness that some patients report. The innervation that the fifth cranial nerve supplies to the sinus cavities underscores the confusion in attributing pain ascribed to this area. The branches of the V2 supply the anterior dura, allowing for referred pain in this region.
(Enlarge Image)
Figure 1.
Diagram Showing That the Dorsal Root Entry Zone of the Trigeminal Nerve can be Variable in Length and May Extend to a More Distal Portion of the Nerve.
Symptoms will predominate in the V3 (15%), or V2 (17%), and the combination of V3 and V2 (32%), and rarely start in only the V1. All three divisions are affected in 17% of patients at onset. The use of medications may add to the diagnosis. There are reports of the unique sensitivity of TN to carbamazepine, and this is sometimes proffered as a fundamental part of the essential history. Carbamazepine will reduce or alter the pain in 70 to 90% of patients with TN, but also in 67% of patients with related head and neck pain. There are no convincing reports that carbamazepine reduces trigger zone hyperalgesia. The response to this drug will not eliminate the diagnosis, but it may presage an improved surgical outcome (PJ Jannetta, personal communication, 2003).
Abstract and Overview
Abstract
The diagnosis of facial pain has been a source of confusion for neuroscientists and primary care givers alike. The profusion of various subtypes, differential syndromes, and confusing nomenclature is silent testimony to this dilemma. The author presents a simple scheme with which to arrive at the diagnosis. The use of the patient's history, confirmed by the physical examination, can be supplemented with some of the tests described herein.
Overview
Trigeminal neuralgia is a well-known condition; neuroscientists working in the fields of neurology and neurosurgery are well acquainted with the syndrome. The diagnosis is made nearly entirely based on the patient's history. It should be a simple matter for physicians to make the proper diagnosis, but it is not. In a survey of patients with TN, 90% had experienced pain for more than 1 year before receiving an accurate diagnosis, whereas 13% went 10 years without a diagnosis. With an incidence of four cases per 100,000 in the US, individual practitioners in medicine and dentistry will see very few cases of TN in their careers. The rarity of the cases contributes to the rates of misdiagnosis and inappropriate treatment. Indeed, Tew and van Loveren found that 33% of their 1100 patients with TN had undergone unnecessary dental extractions.
First described in the 1600s, the clinical picture is one of pain and symptoms confined to the facial area; there are no systemic components to TN. Wartenberg suggested that the hallmarks of TN would be paroxysms of pain confined to one or more of the three divisions of the trigeminal nerve. The pain is predominantly unilateral, and is described as electric, lancinating, focal, and sharp. It can last for seconds to minutes initially, and sometimes lasts as long as 1 hour. Usually the patient is symptom free between attacks. Later in the course of the disease, patients report dull, aching, constant pain in the same distribution as the paroxysms.
Most patients experience a cyclic history of the pain, with the interval between attacks lasting weeks, months, and occasionally years (most patients experience a shortening of the interval between attacks in the course of a decade). Often, the interval between attacks is marred by an increasing level of paresthesias in the nerve. If questioned, patients will frequently report sensations of clicking in the ipsilateral ear, possibly related to the motor innervation of the tensor tympanii. There can be pain in the external auditory canal, in the area subserved by the trigeminal nerve. The external auditory canal is innervated by the ninth, 10th, and fifth cranial nerves and by the geniculate ganglion. The trigeminal and vagoglossopharyngeal nerves supply the majority of the external auditory canal; this is the correlation with the auricular pain.
The pain can be triggered by nonnoxious stimuli (chewing, talking, wind on the face, cold, and light touch). The classic trigger(s) will produce pain in divisions beyond the one so stimulated. The trigger represents allodynia in facial pain. This is due to central sensitization in addition to the peripheral initiator. Allodynia is the result of A-beta fiber activity with neuronal reorganization at the level of the dorsal root ganglion and rostrally. Many patients will describe a sense of pulling, fullness, and flushing in the affected area of the face. The patient usually can describe the first attack in detail, as to the time, place, associated events, and pain course. The pain can also be triggered by positional changes of the head. Typically, lying down on the side of the pain will provoke an attack, whereas rolling to the other side can minimize it. Patients will attribute pain at night more to these positioning phenomena than to contact with bedsheets in sleep. This correlates with the same position-provoked pain during the day.
There can be a family history in approximately 5% of patients with TN. Five percent of patients will experience bilateral sequential pain. More women may present than men (7.2 compared with 4.7 per 100,000), with the peak decade of presentation being the sixth. The age range at presentation in my experience is 22 months to 94 years. There is some controversy about the frequency of side of presenta-tion. White and Sweet reported right-sided pain in 61%, left-sided in 36%, and bilateral in 4%. Investigators in other studies did not find a propensity for one side or another.
Systemic illnesses such as multiple sclerosis, Lyme disease, and Charcot-Marie-Tooth disease can be part of the cause of the pain. Chiari malformations may exacerbate the pain of various cranial nerves, including the trigeminal nerve, as can other pathological phenomena discussed in the Differential Diagnosis section. These conditions can produce sequential pain on the contralateral side, or increased incidence of bilateral pain. Most often the pain is due to vascular cross-compression of the root entry zone (Fig. 1) of the main sensory root of the trigeminal nerve, the portio major, in the posterior fossa. This can include the area of the mixed motor and sensory fibers of the motor root, the portio minor. It may well be that cross-compression in this latter region produces the symptoms of facial pulling, facial fullness, and heaviness that some patients report. The innervation that the fifth cranial nerve supplies to the sinus cavities underscores the confusion in attributing pain ascribed to this area. The branches of the V2 supply the anterior dura, allowing for referred pain in this region.
(Enlarge Image)
Figure 1.
Diagram Showing That the Dorsal Root Entry Zone of the Trigeminal Nerve can be Variable in Length and May Extend to a More Distal Portion of the Nerve.
Symptoms will predominate in the V3 (15%), or V2 (17%), and the combination of V3 and V2 (32%), and rarely start in only the V1. All three divisions are affected in 17% of patients at onset. The use of medications may add to the diagnosis. There are reports of the unique sensitivity of TN to carbamazepine, and this is sometimes proffered as a fundamental part of the essential history. Carbamazepine will reduce or alter the pain in 70 to 90% of patients with TN, but also in 67% of patients with related head and neck pain. There are no convincing reports that carbamazepine reduces trigger zone hyperalgesia. The response to this drug will not eliminate the diagnosis, but it may presage an improved surgical outcome (PJ Jannetta, personal communication, 2003).
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