출처:트레이시 A. 밀리건, 메릴랜드; 타마라 비 카플란, 메릴랜드; 미국 매사추세츠 주 보스턴에 신경학, 브리검 및 여성/매사추세츠 종합 병원
신경 검사의 각 섹션 동안, 심사관은 환자를 평가하기 위해 관찰의 힘을 사용합니다. 어떤 경우에는, 두개골 신경 기능 장애는 쉽게 분명하다 : 환자는 특징적인 최고 불만 (냄새 또는 디플로피아의 손실)를 언급 할 수 있습니다, 또는 얼굴 신경 마비와 같은 두개골 신경 개입의 시각적으로 명백한 물리적 징후. 그러나, 많은 경우에 환자의 역사는 직접 두개골 신경 병리를 제안하지 않습니다, 그들 중 일부는 (예컨대 신경 마비등) 미묘한 증상이있을 수 있으며, 만 신중한 신경 학적 시험에 의해 발견 될 수있다. 중요 한 것은, 정신 상태의 변경과 관련 된 병리학 조건의 다양 한 (일부 신경 퇴행 성 장애 또는 뇌 병 변 등) 또한 두개골 신경 기능 장애를 일으킬 수 있습니다.; 따라서 정신 상태 검사 중 비정상적인 결과는 신중하고 완전한 신경 학적 검사를 촉구해야합니다.
두개골 신경 검사는 신경 해부학을 적용합니다. 두개골 신경은 대칭적입니다. 따라서 심사를 수행하는 동안 심사관은 각 면을 서로 비교해야 합니다. 의사는 체계적인 방식으로 검사에 접근하고 수치 순서에 두개골 신경을 통과해야합니다.
| 나는 | 후각 | 냄새 |
| II | 광학 | 시력, 포피라피 반응 |
| III | 오큘로모터 | 수평 눈 움직임 (첨가제), 효과적인 천체 반응 |
| IV | 트로클레르 | 하향 수직 눈 움직임, 눈의 내부 회전 |
| V | 삼차 | 얼굴 감각, 턱 움직임 |
| VI (주) | 복근 | 수평 눈 운동 (납치) |
| VII | 얼굴 마사지 | 얼굴 의 움직임과 강도, 맛, 큰 소리의 약화, 감각; 외이도의 전방 벽 |
| VIII | 어쿠스틱 | 청각, 전정 기능 |
| IX | 글로시인두 | 인두의 움직임, 인두의 감각, 후방 혀 (후방 혀의 맛을 포함), 외이도의 대부분 |
| X | 바갈 (주) | 입맛, 인두, 개그 반사, 내장 소리의 움직임과 감각 |
| XI (동음이의) | 척추 액세서리 | 흉골과 사다리꼴 근육의 강도 |
| XII | 저체형 | 혀 돌출 및 측면 운동 |
표 1. 12 개의 두개골 신경과 기본 기능
두개골 신경 I (후각 신경)는 냄새의 감각을 전달하는 순전히 감각 신경이며, 대부분의 검사 중에 일상적으로 테스트되지 않습니다. 두개골 신경 II (시신경)는 중추 신경계에서 빠져 나갈 때 직접 시각화 할 수있는 유일한 두개골 신경입니다. 축삭은 시각적 정보를 전달하고 푸필리 반사의 발포성 사지를 구성합니다. 푸필라 반응의 시험은 또한 두개골 신경 III (oculomotor 신경) 부교감 섬유의 기능을 평가하며, 그 중 부교감 섬유는 푸필라 반사의 효과적인 사지를 형성합니다. 두개골 신경 검사는 두개골 신경 III, IV 및 VI에 의해 통제되는 외반 운동의 평가를 포함합니다. 두개골 신경 III는 우수한, 내측 및 열등한 정류 근육뿐만 아니라 열등한 경사 근육을 내면으로 내면과 수직 평면에서 눈을 움직입니다. 두개골 신경 IV (nerve_ 트로클레어는 눈을 아래로 바깥쪽으로 움직이는 우수한 경사 근육을 내면으로 바합니다. 두개골 신경 VI (복부 신경)는 눈을 납치 하는 측면 직사각형 근육을 내면. 내측 및 측면 정류 근육의 기능은 간단합니다 : 측면 교정은 수평 평면을 따라 측면 움직임을 의미하는 납치에 관여합니다. 수평 평면을 따라 눈내내이동을 이동하는 내측 정관 부관. 나머지 근육은 각각 하나 이상의 방향으로 움직임을 일으키고 고도 / 우울증, 납치 / 첨가제, 흡입 / 강탈 / 강탈의 일부 조합.
| 근육 | 내면의 변속 | 기본 작업 | 보조 작업 | 고등 활동 |
| 내측 사각형 | CN III | 예증 | — | — |
| 우수한 정류 | CN III | 해발 | 인션 | 예증 |
| 열등한 정류 | CN III | 불경기 | 강탈 | 예증 |
| 열등한 경사 | CN III | 강탈 | 해발 | 납치 |
| 우수한 경사 | CN IV | 인터션 | 불경기 | 납치 |
| 측면 교정 | CN VI | 납치 | — | — |
표 2. 여섯 개의 안구 근육의 기능.
두개골 신경 검사의이 첫 번째 부분은 두개골 신경 V (삼차 신경)를 테스트하여 결론을 내립니다. 이 신경은 모터와 감각 성분을 모두 가지고 있습니다. 그것은 얼굴 감각, 매스틱 움직임을 제어하고 각막 반사의 발포성 사지를 형성한다. 삼차 신경의 3개의 주요 감각 지점이 있습니다 – 안과, 상악, 및 하악 (또한 각각 V1, V2 및 V3표시).
This video demonstrates a systematic approach to examining the first six cranial nerves. The central and peripheral nervous systems are an integrated system. Therefore, if the clues to a neurological problem are uncovered while taking medical history or during the mental status exam, it should make the clinician more vigilant during the rest of the examination of the nervous system to look for other abnormalities. A clinician should develop a pattern of going through each nerve in numerical order and only document those nerves that were actually examined in the final report. Patients are often being followed for diseases (such as multiple sclerosis) where findings may be changing over time. The documentation from one examination to another are important to follow and the findings should be carefully charted. It is not adequate to just look at the patient and then state “cranial nerves II-XII are intact,” as is so often recorded during a typical physical examination.
The examination of the cranial nerves is essentially applied neuroanatomy, and often the location of a lesion can be identified solely on the basis of physical findings. There are 12 pairs of the cranial nerves, numbered rostral to caudal, which arise directly from the brain. They are named as per their function or structure or the region of innervation. Here, we’ll briefly discuss anatomy and physiology of the cranial nerves-one through six, and demonstrate how to examine these nerves in a systematic fashion
Let’s start with a review of the basic neuroanatomy of the first six cranial nerves.
Cranial nerve I, or the olfactory nerve, is formed by projections of the specialized receptor neurons, located in the upper part of the nasal cavity. The olfactory nerve fibers convey the smell information to the olfactory bulb cells, which then relay the signal via the olfactory tract.
The second cranial nerve – also known as the optic nerve – is responsible for the visual information transmission from retina to the brain. In addition, this nerve constitutes the afferent limb of the pupillary light reflex. The efferent limb of this reflex is composed by the parasympathetic fibers travelling with the cranial nerve III, also known as the oculomotor nerve. The parasympathetic axons synapse at the ciliary ganglion, and the postganglionic fibers innervate the sphincter pupillae muscle. Thus, both the cranial nerves II and III are required for the pupillary constriction in response to light. This oculomotor nerve also controls the levator palpabrae superioris – a muscle that lifts the upper eyelid. Furthermore, this nerve controls four extraocular muscles – the superior, medial, and inferior recti and the inferior oblique, that function together to move the eyes medially and in the vertical plane.
Cranial nerve IV, the trochlear nerve, innervates the superior oblique muscles, which move the eye downward and outward. And cranial nerve VI, the abducens nerve, innervates the lateral rectus muscles, which are responsible for ocular abduction. Together, these muscles and nerves regulate the movement of the eyes in the six cardinal directions of gaze.
Lastly, we will discuss cranial nerve V, also known as the trigeminal nerve. This nerve has three major divisions-ophthalmic, maxillary and mandibular. The ophthalmic and maxillary branches have purely sensory function, whereas the mandibular nerve is formed by both sensory and motor fibers. The sensory fibers of all three branches relay facial sensation, and the ophthalmic branch also mediates the corneal reflex. The motor fibers of the mandibular division supply the muscles of mastication.
After this brief introduction, let’s review how to assesses these nerves during a clinical encounter. As the cranial nerves are symmetrical, every test should be performed on both sides and the findings should be compared.
We will start with the examination of the cranial nerve I, the olfactory nerve. Instruct the patient to occlude one nostril with their index finger and close their eyes. Then, hold an odorant, such as coffee granules, beneath the patient’s nose, and ask them to identify the smell. Repeat the test on the other side using a different odorant, like mint toothpaste.
Next, examine the cranial nerve II, the optic nerve. This part of the examination includes ophthalmoscopy, visual field examination, visual acuity assessment, and testing the pupillary responses, which are also controlled by the cranial nerve III. Start with the ophthalmoscopic examination. Ask the patient to look across the room at a slightly upward angle. As the patient is doing so, examine their right fundus with your right eye, and note any optic nerve or fundus abnormalities. Similarly, use your left eye to visualize the patient’s left fundus. The technique and the potential findings on ophthalmoscopic exam are covered in detail in a separate JoVE Clinical Skills video.
Next, perform the visual field test. This term describes the entire area that can be seen during steady fixation of gaze in one direction. The visual field for each eye can be roughly divided into four quadrants by the vertical and the horizontal meridians. The upper and lower quadrants are referred to as the superior and inferior quadrants, outer two are the temporal, and inner two are the nasal quadrants. Start by evaluating the peripheral vision using the direct confrontation technique. Stand about three feet away from the patient, and ask them to fixate their gaze on your nose. Then extend your arms forward and to the sides, such that your hands are in patient’s superior and inferior temporal quadrants. During this test, your hands should be barely visible in your own peripheral vision. Now ask the patient to cover their left eye and continue to fixate their gaze at your nose. Then cover your right eye and quickly wiggle your left index finger in all four quadrants of the patient’s open eye, and ask them to identify where the movement occurs. Use your open eye as the control throughout this test. Repeat the same procedure on the other side. Subsequently, assess for the loss of double simultaneous stimulation. Ask the patient to keep both eyes open and let you know if they see one or both fingers moving. Present to the patient moving fingers in multiple visual fields simultaneously, such as in either upper temporal fields or bilateral inferior fields.
Next, check the visual acuity using a hand-held card. Ask the patient to wear corrective lenses or non-reading glasses, if normally used. For the test, have the patient cover one eye and read the smallest line they can with the card held about 14 inches away. Record the finding and repeat the same step for the other eye.
Next, test the pupillary responses, which can be affected by both-the optic and the oculomotor nerve dysfunction. Before this test, reduce the room illumination. Then shine a penlight in the direction of the patient’s nose taking care not to illuminate the eyes directly. This is done for observing the pupils at rest, for size, shape and equality. Next ask the patient to look across the room and shine bright light directly into each eye. Look for a brisk constriction of the illuminated pupil – the direct response. Also observe the simultaneous constriction of the contralateral pupil – the consensual response. If the patient has a disorder such as optic neuritis-as may be seen in multiple sclerosis-the affected eye may have a decreased direct response, but the consensual response is preserved. Next, perform the swinging flashlight test by moving the flashlight between the pupils every two to three seconds and observing for direct and consensual response. The paradoxical dilation of the illuminated pupil seen during these tests indicates an afferent pupillary defect, also known as a Marcus-Gunn pupil. Subsequently, turn the room lights back on to observe the response to accommodation. Ask the patient to look into the distance and then focus on your thumb placed closer to their face. Repeat this a couple of times to check for the normal constriction of pupils in response to focusing on an object relatively near to the eyes.
Now, let’s discuss the testing of extraocular movements, which are controlled by cranial nerves III, IV and VI. To test the eyeball movement in the six cardinal directions of gaze, ask the patient to keep their head steady, and follow your finger with their eyes as you trace an imaginary letter “H” shape. Normally, the eyes should move together throughout all planes of vision and there should not be any observed eye muscle weakness or development of any double vision. Next, instruct the patient to follow your finger as you move it slowly towards the patient’s eyes. Check for convergence by noting if restriction of gaze is present. After that, move your finger in vertical, and then in horizontal directions and tell the patient to follow your finger with their eyes. Observe for nystagmus-the rapid rhythmic jerking movements of the eye. This may be normal sometimes on the horizontal gaze or as effect of certain medications, but it can also be associated with cerebellar or vestibular dysfunction. Since cranial nerve III also controls the levator palpebrae superioris muscle, ask the patient to focus on a spot and observe the position of the eyelids. Note if ptosis, which is drooping of the upper eyelids, is present. Ptosis can be associated with lesions of the third nerve, Horner’s syndrome, and neuromuscular diseases, such as myasthenia gravis. This completes the cranial nerves III, IV and VI testing.
Next, assess the function of cranial nerve V, the trigeminal nerve. Lightly touch the patient’s skin in each of the three areas innervated by trigeminal nerve divisions. Ask the patient if they can feel your touch and if the sensation is equal and normal on the both sides. Subsequently, test the pain sensation in each of the three divisions. For this, have the patient close their eyes and touch their skin with both the sharp tip and the rounded end of a safety pin on both sides. Ask the patient to describe a sensation as sharp or dull. Also ask them if the sensation is same on both sides. Next, place your hand on either side of the patient’s jaw, and have them bite down hard, while you feel for the contraction of the masseter muscles. This tests the motor function of the trigeminal nerve. Conclude the trigeminal nerve assessment by testing the corneal reflex. Prepare a swab by pulling out most of the cotton at the end, leaving just a few strands projecting out, so as not to injure the patient’s eye. Make sure that the patient doesn’t wear contact lenses. Warn the patient that you are going to touch their right eye, and tell them to look to the left. Then, with a wisp of cotton, gently touch the right cornea and observe for the blink, or the corneal reflex. Similarly, test the left eye and compare between sides.
You’ve just watched JoVE’s video on how to evaluate the first six cranial nerves in a systematic way. We went over the essential steps of the examination, which can help uncover signs of the neurologic disorders associated with this set of nerves. The “cranial nerve exam part II” will cover the testing associated with nerves VII through XII. As always, thanks for watching!
